The Cal-look Lounge

Just finished up reshaping the combustion chambers on my 2275 heads and doing a new valve job. Ran this combo before on one of my motors and could consistently run pump gas and keep engine temps where I wanted them...Will be assembling the motor this week.

Rick M

Those are some big chambers :o

Yes they are....but with the piston combo and deck setting...work well.

RM

Beautiful! Those look exactly like my street car heads,(but I've got 46x36 valves) I'm running 11.2 to 1 without any problems at all...2442, cam is a special grind, .650 x 310*... makes 215 with the belt on through the muffler...

Johl.....Unless everyone realizes it is the piston design, deck and chamber combo...they freak when they see these type chambers. They definitely work.

Rick M

How much compression dies thus motor have?

Johl...I have 42mm x 37.5 valves in these heads.

Rick M

What pistons do you run Rick? I know the sum total of zero about piston specs and would love top learn more.

Its a secret!  Maybe they are super squishys, or Keith black 426 hemi pistons? Whatever they are. They must be domed

Mine are Weisco flat tops with valve pockets....nothing special!

looks kinda like a semi hemi, are you running zero or even positive deck then? or SS..... interesting!

Definitely running zero deck...with a copper gasket

RM

We based mine on the Semi-Hemi, then Clyde did his magic. A bigger intake would definitely make a difference....

They look very similar to the ones on my engine that were done many years ago at the Bergs.  I have run Berg semi-hemi heads on all my performance street motors.  Gee they seem to work too...

YES THEY DO.  When I drove your motor Don I made up my mind to take my heads off and do it!  Plus our discussion with Gary Berg at BUG-IN sinched the deal!

Rick M

Wellll, if the alternative is a conventional head along with lots of deck height, I think I will take the SH heads too.  ;)
They sure look smooth.
T

hi Rick, it just goes to show that some semi heads do work even when a lot of people may disagree.

I got some type 4 SH heads with 105mm flat tops that I can't wait to run.

How many CC's are in those? Whats your target compression?

With a Flat top piston I can't see getting much compression out of it unless the chamber is really smaller than it looks in the picture,  Also a lot of timing advance needed as well.

That chamber would love twin plugs !  ;)

Fixed it ;D

yes i want t know as well what CR you are aiming at, as the semi hemi heads that berg sold were set up for very low CR. what is the difference between these and semi hemi's  anyway.

These heads are heavily worked over by hand to remove all sharp edges and machined cuts.  Valves are also unshrouded (alot). Will give a report on performance when the motor is back in. There are a lot of different combos.  One motor I held a tight chamber and put a large step in the pistons. I like trying new combos.

RM

DYNO IT!!! It's so funny that the majority of the nay-sayers have done little if ANY dyno work...I've been using this chamber design for over 12 years, and have built many, many motors with just the hemi cut, and I can tell you without any reservation that Gene had little idea what he uncovered. In my work with Semi-Hemi heads, Gene was using TOO LOW of compression ratios, and THAT is what makes them hard to tune. Without the "squish area" the fuel can ONLY be fired by the plug. With todays gas, spark control is the best way to control flame travel and combustion. "Deseilizing", or squishing the fuel only leads to hot spots and "accidental" firing. Hence, PING! With the Hemi chambers, I have seen MUCH more even burn patterns, and much more power with the same combos...OK, I'm done...

my heads on joel mohr built 2386, 48 idf motor for my baja, 44 x 37 heads also "adjusted" by clyde. runs very strong. bill

Johl,.....It is funny that I lost my way when building my recent motor. I had already also discovered the benefits and drivability of the hemi style chambers.  I got fed up with how my motor was performing and took my motor down, redid my heads and now I know I will like it more. I ran the combo in my last little driver motor...94x69 (1915). Had 40mm Weber IDFs. I got as high as 33mpg with that motor with a 110 cam.

These heads work.

Rick M

Bill...forgot to ask you what you are running for a cam and what you have your timing set at.

Rick M

Please explain, how was it performing?

I have a slightly different version like semi hemi with a little flycut, so there is a bit of squish around the edge. 43thou deck, 9.4:1 comp on 98 ron petrol, 86B cam. Best power at 28 deg total timing which is quite different to traditional semi hemi thinking. makes 110 kw to the Rear Wheels. Runs good head temps with SE heads. I like it :) Sorry no pics.

rick, cam is a webcam joel picked. 290 x 505, 1.1 berg rocker, shafts, 262 @.050. compression is 9.7, I am at 5k elevation. Don't have later dyno sheets from ken tabers ( 5k elevation) but I seem to remember 24 lbs at 2500 rpm, Still has bottom end, found joel's dyno sheet from his place,(2500 elev.?) prior to kens dyno and joel's corrected hp was 190 @ 6k with 191.5 trq at 4500 rpm with a somewhat restricted exhaust , motor then brought north, rejetted, and a doug berg made new free'r exh. system.  Live up here in northern nevada, carson valley/lake tahoe, thin air, and gets hot in the summer. No pinging or overheating. Thanks Joel. Sorry, can't remember timing.. bill

Crank is in the crank stand and ready for rods....Back to assembling....Also creating a second deck lid for the chop for the summer. I had a spare 67 deck lid that needed a little fixing... Straightened  the dings...prepped a convertible set of louvers (actually later bug that had the same louvers as a convert) and will finish the spare decklid  when I have the chop up and running.

Rick M

I looked at the dyno sheet Bill, and the timing is at 30*...With Dougs new muffler, I would bet that motor made close to 200...yet drives like a stocker...and the 48 idf carbs are off the shelf... with some carb work, i would estimate 210...through the muffler, belt on. 8)

Johl,

I heard Gene mention when he was still with us that he would put a lot more lead in the timing that 30 degrees. Of course, cam combination/overlap and everything else come into play.

Rick M

When I worked for Gene, he said max compression WITH a hemi cut was 7.8 to 1...He recommended 7.5 as a max for stock chambers. With the extra static compression, timing will be moved to accommodate the flame travel of a tighter squeeze.

what type of heads-vw or aftermarket? can that valve combo be used in a modified vw head?

My heads started life as 041s...

I had no problems with my semi hemi heads on my last 1776... I bought them from Rick around 2003 or 2004, actually.  ;D  Anyway, I ran 7.8:1 compression, dual Kads, Engle 100 cam with 1.25 rockers, 1-3/8" header with single quiet pack and 009 with Pertronix, loved that motor.  Ran awesome, despite claims from a number of guys that said the semi hemi chambers would lead to raw gasoline coming right out the tail pipe. lol.  

Only issue I never resolved was a slight flat spot off idle... not sure if it was the 009 or the Kads, but I never took the time to fully tune it out.  Great motor though, and it would go anywhere as well as be fun to drive.

I'm at the point of frustration with my 2017 build that I slightly regret ever having sold that engine to fund this bigger one.  It's been nothing but one headache after another and I'm thinking I should have left well enough alone.

Hey Ryan....were those the ported heads I sold you?  That same configuration works on big motors too.  Doing the same exact thing right now to my 2275.  Glad to hear they worked so well for you.

Rick M

 On the 1776...If you had bumped the compression to 8.5 or 9 to 1, it would have made an easy 10 more horses, with the same temps and no flat spot....

Yeah, Rick, those were the ones!  I have no idea where the engine is now, as my buddy who moved to Portland that bought the engine has since sold the Baja that it went in.  Great comb, all around!  Really miss it.

Very cool. Glad they worked well for you. Doing a set for my Wife's buggy right now. Will be very similar so we have a very dependable but affordable performance combo for her.

Rick M

We should try and keep this thread alive. There is so much new technology that can be applied to a VW, and most people seem to be stuck in the same 40 year old line of thinking. With small stems, and beehive valve springs, you can easily add 1,000 rpm to the same old combo. And with the motor not working as hard to sustain RPM, it just "Unleashes" more power....

Maybe I am confused as to the point of opening up a chamber and then fly cutting it down to get compression back?? Did I miss something or isn't that what you claimed you did?  11to1 with a hemi chamber confuses me.

I'll give my two cents...

If hemi style chambers are so good, why do you need so much more ignition lead with them?

If hemi style chambers are so good, why is the new Chrysler hemi not a true hemi?

If hemi style chambers are so good, why does the new Chrysler hemi use twin plugs?

Hemi style chambers greatly increase the surface area of the chamber, allowing more heat to soak into the head rather than out the exhaust.

I have reshape chamber like that. and I installed on 2276 bay windoy. daily driver. with compression 7.1 ; 1  camshaft engle 110. engine didn't like.  pinging a lot and i have to retard igniton quate a lot. it is on tropical country. pump gas is 86-88. removed it and install normal chamber heads

The HEMI chamber works well with more compression. If they did not work why did the porsche engineers prefer them when building the 356, 912 and 911 motors??? It was not just about putting the larger valves in either. With more compression, you do not need as much timing.

For all of you who continue to think they don't work...don't run them. However, they do work better than the traditional chamber for street driving. You also cannot just flycut the HEMI shape.  You have to go in and radius all the machined surfaces and do a little more work on them. 

This is such an mis-understood subject...It requires more than just the hemi chamber to make it all work. If it did not work, I would not have torn my motor down and gone back to it after trying the traditional chambers again....even when I knew what the outcome would probably be.

ZACH...Twin plugs have been done on VWs going back over 30 years.  It was probably initially done by REVMASTER for the VW airplane engines.  I have a few other friends who did it on VW performance motors too.  It is not necessary with the right combustion chamber and ignition.

I like trying different combos...but personally, the hemi chamber has worked well for me for years and is the reason I am returning to it.

RM

Well Zach....What's wrong with more timing? What's wrong with twin plugs? My head temps are not any higher than normal. I drive my bug to the races,(usually 60 to 80 miles each way) race it and drive it home. Twice I have won my bracket running low 12's on street tires and through the muffler. I can cruise it anywhere I want to go, and I live in the Desert! Temps are not a problem...Most modern motors use a bowl shape of some kind. Some do have a small "squish" areas BEHIND the plug.  Rememeber the Pent-Roof that Honda used? I have a freind that owns a high performance machine shop, and he lets me look at heads that he gets in. ANY BRAND. I invite you to do the same...and Rick, I have gone as high as 10 to 1 on just the Hemi cut...no ping, no deisel, and no extra heat on California 91 octane...

more timing indicates that the mixture is burning slower.

Correct! and....

If you think about what goes on in a combustion chamber, the blended hemi has fewer places to have detonation created. I am with you on the hemi head thing. Been messing with it a long time. Just lost my way briefly due to someone talking me in to something that I had a gut feel I would not like after doing it.

RM

Where are people finding the correct beehive springs?

I was hoping someone else would say the rest ;D I had to learn that this year, but can't seem to find it. having 2 2 inch thick books about combustion engines doesn't help either ::)
it was something about a slower burning mixture releasing less energy or less force

I am interested to see a video of this built which proves the Hemi haters wrong  ;)

Donn at R/D spring does all of my valve train work. He is a spring engineer. Works on Ferrari, Ford, Chevy, Masseratti, you name it, he's made it run better. He's been in the valve spring business for 30 years. He either makes, or has access to any number of combinations based on true lift and duration numbers. Yes, they have a website...

Fish,

When I get my 2275 back in the car, I will take video of it during cam break in and later while in the car driving it. Will be a while but will post here.

Rick M

There is a video on my website of my street car running a low 12 on street tires through the muffler...Mohrprf.com

Johl,

Does your spring buddy Don at R/D make the behive springs and retainers for the single groove valves like CB puts in their heads for a stock VW spring height?

Rick M

The Porsche (and Chrysler) engineers preferred to have a greater valve angle (for more airflow) than VW. A hemi chamber was a necessity, not a choice.

My reasoning for the chamber has nothing to do withe the PORSCHE engineers wanting more room for the more efficient cross-flow design. The more surface area...the more heat.  The more heat...what happens? Also, what does the heat in the chamber produce? :-)

RM

One of the key advantages of a hemispherical combustion chamber is that its surface area to volume ratio is the least in the category a compared to other designs like flat head, wedge heads, etc. and therefore they have a superior thermal efficiency than other engines. Its advantages are that it has a relatively low surface area for heat absorbtion and it has little in the way of areas where unburnt mixture can lurk, as all the corners of a wedge design are eliminated and the raised roof of the hemi combustion chamber are well clear of the piston. The low surface area means that there is less area to absorb heat from combustion and this helps to keep the head temperature down. This in turn helps to control detonation. Accordingly, a reasonably higher compression ratio can be run to the benefit of performance. (But not the kind of compression ratio that most people associate with a racing motor, because this design has definite limitations at higher compression ratios.)

The elimination of dead spots of unburnt fuel mixture means that fuel economy is better because more of the charge is doing work.

Another benefit of a well done hemi design (not just a cut one-which means proper blending of all surfaces) is the effect of "squishing" the mixture so that it shoots out of the "squish area" and the resultant turbulence mixes the mixture up bettr. This helps to give even and controllable combustion.  Two stroke designers adapted these findings and put a concentric squish band around a ( usually) hemispherical combustion chamber with the spark plug in the middle.  Remember the SQUISHY discussions that have taken place on these forums.  Guess what....SQUISH with hemi heads is part of the secret. The rest of the functionality is found in the compression ratio, timing, jetting and how well the chambers are finished with the hemi design.  Look at the head on a 2 cycle motor cycle engine.  The 2 cycle engineers have fully understood for years the benefits of a hemi for the squish necessary to get the best burn on a 2 cycle motor. BURN is BURN...and cylinder head design has a great deal to do with it.  The HEMI also helps to optimize what you can get out of lower octane fuels. I had a 1914 in my chop top before the 2275 with heads similar to the ones I posted here that I was getting 33mpg with (that had the HEMI design) I was running 89 octane fuel.

Johl Mohr has mentioned a key ingredient in this whole discussion and that is that you can run more compression with the HEMI design as detonation is reduced with the combustion chamber design, as all the sharp corners are eliminated when after the machine cut the critical finish of the chamber of all the blending work contributes to removing detonation issues normally associated with all the corners and edges found with a wedge design. All machined edges must be blended and no sharp cuts or edges left.

Everyone can keep kicking this to death but if done properly, the HEMI design does work. You can't just hemi cut your heads and throw them back on and expect an improvement. It is not just about cutting a hemi chamber and lower compression. It has to do with a lot more things related to better atomization of the fuel, burn, eliminating detonation and being able to run lower octane fuels.  

Each person is entitled to do what they want. However, for those of us that have already worked with and run the hemi design with all the corresponding work that goes with them...they do work.  However,  you don't have to run them.  Everyone is free to do what they want but don't bad mouth something you do not understand or simply jump on someone else's bandwagon and try to out theorize people on the forum. Some people talk while others DO.  For those who have done this...we an continue to enjoy the benefits associated with them.

Rick Mortensen

Consider what you are viewing carefully.  We are not talking about combustion chamber volume at this point. We are talking about the design. Look at the diagram I sketched this morning and think carefully about the questions posed.  Take your thoughts away from the compression discussion long enough to think about the design only in terms of chamber surface area and the most prone to detonation. We can still get compression with a HEMI design.  Just focus on other things happening in a chamber to get the benefit of the principles associated with the HEMI.

Rick M

ZACH....Your comment about the HEMI CUT increasing the surface area is actually not accurate.  It increases the VOLUME...but look at the design I posted and ask yourself, if you take the wedge design and calculate all the surface area with the corners, which has more surface area?  Plus, which has the bends and corners that are known to contribute to detonation issues?  There is something to learn here GRASSHOPPER.  :-)

RM

So what does the piston look like? You eluded to it being special.

Not to mention the benefit of unshrouding the valves...

Taylor,

The piston is nothing special. You can run a flat top...providing you have valve clearance. I actually have eyebrows in mine...with the k8 cam. There are a lot of combos you can run.  Did you see my sketch?  The focus I have is on eliminating surface area and all the corners in favor of a better design for pump gas.

RM

RickM and Joel,
Well stated.

I am not saying it won't work, I am questioning whether or not it would make the same power, with the same compression, as a wedge head? Once you hog out the chamber and then flycut the head to get your compression back you are having to notch the pistons, adding to the surface area you find so critical. That wouldn't be necessary with a wedge head running 8.5 to 1 and around .580 lift.  Also,  if you have a quench pad on a chamber and .050-.060 deck, that isn't the area where detonation would occur anyway. A flat quench pad doesn't turn into a glow plug.  Joel claims to have a hemi style head on his car,  which I believe they started,  BUT... his 2442 has 11.2 to 1 so that means that supposing he runs .060 deck with around a 4ccc notch in the piston for the .600+ lift that puts his heads at 45cc much to small to really be a hemi style. Or maybe he does have a trashcan....I mean hemi style chamber,  than he has domed pistons.  

Taylor,

In my application I am not trying to run 10 or 12 to one compression.  If I was, I would be running a domed piston in the hemi chamber that was profiled to be a reverse match to the combustion chamber with valve pockets in the piston.  That is just my opinion.

My focus is on a street motor that will run on pump gas, make reasonable power, not over-heat or detonate and be dependable no matter what pump I pull up to, whether it is Billy Bob's gas station in Oglalla, Nebraska, or a good quality gas from a big known producer.  I don't think in terms of who has the fastest car on the block. Already went through all that about 30 years ago. My focus is driving anywhere, at any time, in any temps, with any variety of crap that comes out of a pump from Arizona to the East Coast (or West Coast) and back.  I don't try to mix a drag racing combo with a street combo. That story is getting too old to keep kicking to death.

I cannot speak to what others are doing but I do know the hemi chamber will work in a lot of different configurations, even with more compression, providing the piston combo with the head is correct.  I cannot speak to what others are doing in this area.  I just know the open chamber works well for what I have done and will return to doing.

Rick M

RickM and Joel,

would like to here more about your thinking on the open chamber mods-have beaten my GBE tech articles to death on heads/head design/flow/driveability.
what mods have you discovered/tested/found to work since Gene wrote about them years ago .

RickM, appreciate your thinking on driveability and recognize that your thoughts seem to mirror the issue of driveability/longevity GB wrote about.
thanks

I try real hard not to drink anybody's Kool-Aide, but the VW world is notorious for stagnant thinking. The problem with the old semi-hemi stuff always seemed to be the chambers and resultant low compression. Bad combo. But if we're now shallowing up the chamber and putting some real compression to it, then it might be worth a try?

Where are the dished pistons? Let's take some of the chamber out of the head and put it in the piston.

0 deck and 56cc chambers...I'm not here to argue, frankly I have more important things to do. If you don't beleive it, just go away. I am trying to spread evidence of new technology to help benefit the hobby. What I have done is taken Gene's theory to the next level. After examinng many other types of chamber designs, I decided to try this as an alternative to actually CNCing a modern shape...

Three pages deep and you still haven't spilled your compression ratio!

The drawing you posted is for the guy who wants 7:1 compression on a 2 liter plus engine. He has the option of adding a ton of deck (which we can all agree is bad) or hemi-ing the chambers. Of course the surface area is greater when you are using all that deck surface as combustion chamber, but when it's tight (.040"-.060"), you can't really consider that as an equal part of the chamber.

The smart builder knows to smooth the bends and corners in a wedge head. You don't have to hemi cut to achieve that.

I still don't buy that the hemi will outperform the wedge with all other things being equal. Burn is too slow. Twin plug it, then it may show an advantage.

Johl is right...I ran around 9.0 to 1 in my 2110 that I drove to Detroit, Michigan, and back, in 1997.  You can get to 56cc in these type of heads. That is what flycutting is for.  I agree with Johl....if you don't like it....don't do it.  However, for those of us willing to tear down a motor and redo heads just to prove a point, we are the doers and not the talkers.  There are a lot of pontificators on these forums who have not done what they have opinions on.  I like to use my own vehicle as a test bed for ideas and will do so with this round of testing....or I would not have torn it down to go back to a design I know works.

It is hillarious that people who have done very little of what we are addressing are so knowledgeable on the subject.  Proof is in the pudding.  My motor will not be 7.1 compression.  I would not run that low a combo if you gave me free parts. IT will be close to 9 to 1 with "0" Deck, another thing we did in my 2110cc motor.  What we are doing...where I agree with Johl,... is taking the hemi chamber to another level. The technology for this is not new....and yes, it does work.

I use a close friends motor as a great example.  Don Bulitta's motor (realistically) with his 94s now on the engine,  probably makes somewhere around 8.4 to 8.5 to 1 compression.  He would have to verify that.  He had his wife throw me the keys one night and let me drive it.  CLYDE BERG did the heads for it and yes...they have the massaged hemi chamber.  If you want to ride in a fun car....this motor with the 5 speed is a blast to drive. Pulls very hard, has incredible torque and guess what...can run pump gas.  Don's is just one of many combinations like this.

When I got my CNC CB heads....I decided to run the combustion chamber design that came with them out of the box....after going over the combustion chambers to debur and prep everything to help alleviate potential detonation points.  It was against my better judgement after already having hemi style heads with 9.0 to 1 compression.  I did my own ports and then assembled the motor.  It would run absolutely cool and fine while driving like a stocker.  It did not have heating issues. However, hammer it and take it to 6500 a few times or push it over 100mph for sustained bursts and it would not go below 220.  No motor I have ever run has has this issue, even a turbo-charged motor.  I spent hours on tin fit, cooling mods, oiling mods, you name it. So, the verdict....tear it down and go over the heads to reduce the chamber surface area and reset compression. That is where I am at.  The motor will be assembled and back in by Labor Day...so I will have plenty of ambient heat to test it out with. I will post the results.

Everyone can do what they like.  I will be close to 9 to 1 on my motor, similar to what my 2110 cc motor was.  Heads can become a heat sink. Less area in the combustion chamber means less heat retention.  The sketch I did about volume vs the surface area discussion was not about a 7 to 1 compression motor. It was about combustion chamber design.

Our push in 1996 to drive our cars with big engines 5000+ miles was to dispel that a motor big cannot live and be dependable driven long distances.  So, the next challenge is proving higher compression motors with different combustion chamber designs can be driven with more compression even on 89 octane gas. I am not trying to drive to the track and run 12 second passes.  The proof, which I already know works, will be in the results...which will get posted when it is back on the road. The squishy concept has already been proven....I am just approaching it a little differently.

My focus is making great torque, with pump gas, achieving low temps for sustained periods in 110+ degree temperatures.  In Arizona we do not have the luxury of the median temps of Orange county or the San Fernando valley area.  It does get hot there but not like Arizona.  Getting a 2200cc motor to run in the Arizona temps is in a different class of its own.

Rick M  

Joel and RickM,
count me in.....
Excellent points made. I ran into the same here regarding removing auxiliary venturies despite the factual evidence that such a modification had been done in Britain in the early 70s without any noticeable performance improvement.  The arguement was somewhat simplistic-that because it was tried already, that such thinking was impeding improvement. The problem with this was that "new exploratory thinking" was framed in a way that disregarded all documented laws of physics and mechanical engineering, in particular airflow, that are used the world over. I certainly am one that appreciates change when there is noticeable performance achievement not limited to the quartermile.

Joel, will be contacting you via pm about heads

Appreciate your thinking and taking the tried and true Berg way to another performance level.

Rick, tell us all of the changes being made to your engine this go round.

No offense or personal attack here, just never heard of anyone hemi cutting a VW head on purpose, only out of necessity.   I have a swimming pool for a piston in my motor.  Good luck to you....Taylor

Taylor,

Wish I had my old BERG thick crown pistons to post a shot of. I sold them to someone on the CLF but cannot remember who bought them. I used a combination of a sligthly opened chamber and a dished piston in my 2110. It worked fantastic. Used an MSD ignition...which I also liked. Never did a jet change in the motor on the BERG 97 cruise....regardless of the town we passed through, elevation, weather, etc. Got over 24 mpg with Dellorto 48s on the road trip (5200 miles round trip) and never over heated.  Did a 100mph blast against a mustang GT somewhere in the middle of Wyoming on hwy 80.  Was a great motor and had between 8.5 to 9.0 compression.

A lot of different combos work. That motor had a really small PAUTER cam but the combination of the cam overlap, combustion chamber design and static compression we set worked incredibly well.

ZACH....I will post all changes made.  I am staying with the same cam/rocker arm combo so I can do a comparative analysis on the results to the cooling and performance.

Rick M

FWIW, the problem with these arguments is that, historically, most VW enthusiasts can't tune their way out of a wet paper sack, and they compound this issue by picking the choice characteristics from different philosophies of engine-building expecting them to work well with one another when put together. IMO, if you have detonation with 8.5-9.0 CR with either a wedge chamber or a semi-hemi chamber, then you've done something wrong; you either have a complete mis-match of engine components elsewhere that is independent of the combustion chamber, you can't tune your engine, or both. Kudos to Joel and Rick for shirking the dogma, refining their combos and showing it can work. It doesn't follow the engine-building philosophy that I adhere to at all, but there's more than one way to skin a cat. And just because you or anybody else couldn't successfully do it doesn't mean it can't be done.

Thank you Stripped...The CB Wedgeports from Bills 2387, 122 Web cam, only .506 x 288 and it makes about 200 hp at 9.7 to 1

.....Just my 2 cents worth but I was there in the beginning when the original R&R testing was performed @ 7. and 7.5 and one engine at 8.5 later on...  and found that the optimal timing was 10 degrees avanced and that at 42 degrees made the most power  and made the heads really come alive with NO adverse criteria . Since then i have performed several teardowns from some mileage motors with this head design and can tell you first thand that the heads overall, looked Bitchin'. The chambers all looked good with no seat movement,or visible cracks, or distortions of any kind. The" heat sink" issues with most other heads(vw oem) are non existent with this chamber design and there is a lot to understand here in terms of changing the basic format as we all have come to learn and love. I realize that these were basic low compression models but the technology is the same across the board.  Rick M. and many others have had good experience first hand and I know Joel and of his relentless research on this subject and can tell you that his shit rocks the house and he has come a long way since being>> The little skinny grinning kid in the back ground/LOL...   I dont know if this has hindered or helped but just my 2 cents of input. Happy motoring to ALL.......   Dyno

Thanks Don... Does anybody realize that most modern motors run between 9 and 13 to 1 on 87 octane? It proves the envelope exists, and all we need to do is adapt our little air cooled to modern technology...to make more power with the same temps. And one facet of this development is spark curve. Right now we are just "fidddling about" with the 009 because it's the most readily available. With CBs new programable distributor the options may grow...put THAT in your hat rack! 13 to 1 on 87???

I thank you too Stripped!  Smokey Yunick, the famed V8 engine builder, is one of my heros.  He did many unconventional things that others said would not work but guess what...He kicked everyone else's butt!

Being a business person I read a lot.  There is a book out that was written in 1963, by author Thomas Kuhn, called "The Structure of Scientific Revolution". The whole premise of the book is that the greatest BREAKTHROUGHS in science, business and industry, came from BREAKS WITH OLD WAYS OF THINKING!

Like Johl, I found out that my modified hemi (open chamber design) has a great deal more to do with motor heat dissipation and equalized squish across the entire piston area than I thought.  I got caught up in traditional ways of thinking for awhile too. Finally, after struggling with heat issues when I first moved to Arizona in 1982, I had an epiphany when I finally realized the traditinoal wedge head combination that was creating the most issues for me. Mike Fischer years back talked me into one of the first hemi type designs and I modified it beyond the machined finish, much like Johl does.  This is why after my out of the box wedge chambers did not perform the way I wanted, I did not hesitate to rip my new heads right back off my motor and revert to a design I know works.  I like your statement that just because others could not figure out how to make something work does not mean it will not work. Never were truer words spoken.

Dyno... thanks for your input too.  I have first hand, personal experience with the chamber design.  In fact, I was pleased to hear from someone who posted on this thread who bought some old modified hemi chamger heads I had done over 10 years back.  He used them, loved them and wish he still had them. The design works.  Bill Rogers can confirm this too...as his baja has a giant motor with the hemi heads which Johl Mohr assisted with, it makes serious horsepower. Bill lives in Carson City, Nevada, where the elevation is also higher. He loves the combo from his feedback to me.

Our hobby is hilarious at times.  Truly there are those who think just because someone else could not make it work that no one can. Pretty limited, shallow thinking. I simply let it flow in one ear and out the other because I work to validate a process rather than comdem it before I have personal experience it will not work. In a few weeks I will be having fun when I get my 2275 back together and fire it up and go out and prove a point. I will not forget Gary Berg's face at the Bug-In last spring when I told him I had bolted on some heads to my street motor with the traditional chamber.  He got a pretty funny smirk on his face....and I knew why.  I had gone against what I have already proven would work with an open chamber head.

Johl,  all we can do is continue to enjoy what we've learned and let others simply keep telling themselves that their way is the only way. In the meantime, we can continue sharing with those who will listen. I will be taking pictures as I re-assemble my motor and post them.  I don't have any issues sharing things I have found helpful.

Rick Mortensen

Rick,

I am listening,I like to think I am not too blinkered to ignore something that works,will be interested to see how you get on with the engine now,I can see some benifits of opening up the chamber,semi hemi or in other ways,and then flycutting them down to get your required compression.

One thing I ask,can you please spell Joel's name correctly :)



Joel what you are doing is also very interesting,but as you are looking to these modern fuel efficient lean burning cars,arent you missing the most basic change in modern cars to our antiquated old VWs, EFI? I am sure CBs new distributor will give advanges over a 009,but there is so much left on the table to be had with EFI

Just my thoughts :)

cheers richie

Richie...will be posting some shots as I start the assembly. I am not in to the 7 to 1 compression motors.  I am purely a fan of the open chamber with higher compression. With the new thick crown heads....it gives you the meat to do the mods and still have a strong upper chamber cross section.  I will stay in touch with you.

How is that nasty pro mod vert of your running. Hit the 8's yet? I have not stayed up on your ETs.

Rick M

All very interesting and cant wait to see some results ;D, Id never head of hemi cut heads on a vw, will there be any more build pictures of the heads and pistons? 

cheers

Yes, I understand that EFI is a major consideration, but after the fuel is delivered, the valve closes. Then it's up to the conditions within to fire the charge, and make the most of it. THAT is the envelope I'm working on...

Joel....I agree. The head does not know what method of fuel delivery is being used.  Fuel management is different than combustion chamber design and efficiency. They work in synergy but each has its own parameters of efficiency.

Rick M

EFI is so much more than that,the ECU gives the ability to control everything going on in the car,now you are sounding like those that you critisize, your not being open minded to learn new things? :o :)  just messing guys,but it does come across like "do as I say.not as I do"

Anyway as this is the Cal look section of the lounge I will stop my talk of efi as its nothing to do with cal look is it :)

Richie....on the contrary..I agree with you about the engine management capability with computers and EFI.  I am not criticizing anyone.  Just suggesting they don't hold such a closed opinion on the hemi or open chamber design. It almost sounds like everyone thinks the only motor you can build with an open chamber design only has 7 to 1 compression.  That was just one mans opinion.  We are talking about putting more compression to the design and taking advantage of it.

My discussion is primarily around the naturally aspirated carburetor motor... I am definitely not advocating that what I am trying is something anyone has to do. In fact, an open chamber or hemi type head is better for supercharged applications too. Think about it for your turbo configuration. :-)

Here is a quote off the www.corvettefever.com website about open chamber heads:

"The first open chamber appeared in '69 ZL-1 aluminum heads. Cast iron heads with open chambers first appeared in late 1970 for the '71 model year. Without question, a big-block will produce more power with open-chamber cylinder heads. In fact, the improved air flow and combustion efficiency offered by the open-chamber design is frequently sufficient to more than offset the loss in compression ratio (which can be over a full point) produced by the increased combustion-chamber volume."

Read more: http://www.corvettefever.com/techarticles/corp_0611_chevy_big_block_cylinder_heads_pcv_valves/viewall.html#ixzz23YaGZQUT

Just some more good information to show this is nothing new.

I like trying new things and not getting stuck in a rut.

Rick M

When we get this settled we should move on to religion and politics.

Settled? If you're not open or accepting, go on your merry way....I'm not arguing...just stating my findings...

ZACH....the truth of the matter is we are not settling on anything but what we know works.  Run what you like...There is really no argument because we are simply running what we have done and seen be efficient. We are not the only ones who have done this.  GM, DODGE, FORD and many other automotive engineers have designed motors and understand the benefits of the open chamber design.

Again, break out of that 7 to 1 compression paradigm being the only reason someone did a hemi type/open chamber head.  Neither Joel or myself is advocating that. In fact, I may even bump up my compression to 9.5 due to the K8 cam and overlap.   :-)

Rick M

Rick,
    Very interesting thread. I look forward to hearing how your motor runs! Should be a great runner with plenty of usable power. ZACH is on the cocktail train again! ::) ::) ::) Keep us posted!




Thank you

Relax fellas, it was a joke! Thanks for proving my point though, you just can't joke about religion, politics, or hemi-ing your VW chambers without someone getting their panties in a wad.

I'd still love to know why the engineers at Chrysler designed the modern hemi engine like this, if a true hemi is where it's at. Perhaps you know something they don't.
(http://www.davemikulec.com/blog/uploaded_images/2008_1231MiscImages0040-733307.JPG)

A true hemi is not necessarily "where it's at", nor is anybody arguing so. The combustion chamber shape is always going to be a compromise between quench, valve shrouding, valve clearance and volume (compression ratio). Why did Chrysler design their current head with a pentroof chamber instead of a true hemi chamber? For starters, the increase in chamber volume with a true hemi would decrease the compression ratio, and attempting to deck the head to reduce chamber volume would expose the intake valve seat and decrease the available valve to piston clearance. Compare that to a Porsche 911 chamber (aircooled). Why did they use a true hemi?

Joking or not, why do you insist on being contentious?


While I am not a proponent of the semi-hemi chamber in our VWs, the open chamber Rick points us to in this article is a great example of where to open the chamber: behind the spark plug. One problem I see with the semi-hemi modification is opening the chamber opposite to the spark plug which increases the distance that the flame-front will travel; biasing the unshrouding and semi-hemi cut on the spark-plug side should mitigate this. However, having gone from a 12:1 CR, Supersquish piston, 91 octane engine to a 9:1 CR turbo engine with a lot of boost, I'm certainly rethinking the influence of my current chamber shape as I have a ton of deckheight (~.200"), reducing the effectiveness of my Supersquish pistons:
(http://images.thesamba.com/vw/gallery/pix/490629.jpg)
I could lay back the combustion chamber on the spark plug side to pick up more volume and reduce the deckheight to something marginally acceptable.  ;D

I am truly looking forward to your results, Rick. Especially if all other factors remain the same, especially deck height and compression. Otherwise, this conversation is a moot point.

Zach....agreed.  My whole intent was not to change everything on my motor.  Just go back to the open chamber quench set up I ran in my 2110. I will post my results once back up and running.

RM

Stripped66,
great perspective on your openess to thinking about people improving on those techniques that have been known to work over the years and current applicability.

Many thanks to RickM and Joel for continuing to take the research and theory and convert it to the real world-in both their own motors, in Rodgers' motor description (especially at that elevation) and performance, and the Bulitta motor, Clyde's work over the years. It seems to me that the evidence is very substantial that this "new way" is a substantial performance improvement.

For those who question, congrats to you for raising the questions for it sharpens the work and effort that Joel and RickM have undertaken and will continue to do. While you may not agree with or accept their work, the reality is that their effort is the evolution of and improvement on conventional thinking. Thats a good thing. Its like looking at a 1965 Porsche 911 and 2012 Porsche 911-same original design theory but substantial improvement and evolution through the years.

Looking forward to seeing the results on the road

.

Exactly !   ;)

Keith...no input??? :-)

RM

Nope... :)

But I do recall the comment of an F1 race engineer friend of mine when viewing the engine in the Chop-Top: 'You do realise that for as long as you guys insist on running carburettors, two valves, single plugs and no management system, anything you might plan on doing with the engine is the technological equivalent of rearranging the deckchairs on the Titanic. It ultimately serves no real purpose.' Harsh, but it made me smile!

Keith, we are always faced with a certain 'prejudice' towards out humble flat fours. Curiously, we can easily make over 200 horsepower with, wait for it... carbs, two valves per cylinder and a crappy old distributor.

Cosworth engineers, spent millions on developing 16V heads, fuel injection, Cdi ignitions, complex management and a turbocharger to produce just 220  horsepower out of 2 liters when they souped up the Sierra.  The result? a car that struggles to do a fourteen second quarter in standard trim...

I bet, if your F1 guy watched our drag racers pitch up against all of today's supercars, he would dine out on his flat cap.  ;D

Bugatti Veyron: 1000 hp, 4-wheel drive... half a second slower to the quarter than my old 2.1 liter Waterboxer from a 1980's VW Van, of all things.

As they say, the bullshit stops when the checkered flag drops  ;)

I don't think you need to tell me of the flat-four's capabilities after all these years.  ;) But what your argument does forget is that you're comparing a "slightly" modified VW to a production car. Wonder what the guys at Bugatti/VW would do if they built a purpose-built Veyron drag car? Also, the Sierra of which you speak is 25 years old – and, more importantly, was designed to a) meet certain emissions regs and b) drive a lot further at max rpm than 440yards. There's really no point in comparing the two and, as we all know, we have nothing to prove.

Perhaps a fairer comparison would be take take a stock 1600 GT Beetle and compare with a stock RS1600 Escort – same era and same engine cc.  :D

25 years ago is like yesterday... The So-Cal boys were running elevens forty years ago  ;) Albeit a quarter mile per rebuild  :D

You're right about comparing apples with oranges, though. My point was mainly about the prejudice we always seem to face among racing 'peers'... They always seem to knock the VW even when it kicks their ass!  ;D

Matt

RickM,

appreciated your thinking. Could not agree more. Key point is longevity on the street. Keep up the thread.
Thanks to you and Joel for bringing fresh thinking into this enhancement and expansion of VW aircooled performance thinking

Stripped, I understand there is a compromise involved. Isn't there with anything we modify? The Chrysler and Porsche engineers could (and did) easily get their CR back up with domed pistons. Not so easy for us...

There are aspects of this that I do like. Even pressure across the piston. And the ability to flycut the heads can make a wide stroker motor much more easy to deal with. Years ago, CB told me you could safely flycut .140" off an 044 casting. That's huge! I wonder what a "open chamber" flycut down .140" would CC at? Dish the pistons if needed, valve pockets of course. Stock width 2387cc N/A street motor sounds very feasible.

I still doubt that a single plug can efficiently light off a wide chamber like that. Twin plugs would really wake it up.

The first motor I built was semi hemi cut, and fly cut. And throughout the years, the only thing that more than 32° timing has done for me is make the engine much more difficult to start.

And as for me being contentious? For my amusement, purely ;D

More food for thought from the website 351.net where V8 guys are sharing input on combustion chamber designs:

The 351C open combustion chamber head is superior to any wedge combustion chamber design. It makes as much power as the quench chamber version … its not prone to detonation any more than the quench chamber version. Poly-heads don’t depend upon squish for their power and resistance to detonation, those characteristics are achieved by the shallowness and poly-angle shape of the combustion chamber.

The 351C chamber is very shallow, the valve angles are merely 9-1/2 degrees. There is no dead space. The chamber cross-section is not wedge shaped. This shape evenly distributes the flame front over the entire surface of the piston dome.The best intake port in the world feeding a mediocre combustion chamber will not make big horsepower

Engine designers realize the combustion chamber is the heart of an internal combustion engine. The best designed intake port in the world cannot produce superior torque and horsepower if it is supplying fuel and air to a cylinder with a poor or average combustion chamber. The 351C had the highest volumetric efficiency of any mass produced push-rod (OHV) V8 not solely because it had well designed ports and large valves, but also because it had a well designed combustion chamber. Although it may not be intuitive, what you are looking at in the picture below is one of the best performing combustion chambers of any mass produced push-rod V8.

Look closely at the 351 head and then what Joel, I and others are doing with the open chamber VW head designs we are working with. Keep in mind you do not want a lot of deck.  I run "0" deck with a copper gasket.  I know Joel is running a tight deck too.  First we get the design, then we get the CC's we need...and then we assemble.  My personal decision of going to an open chamber design has come after hours and hours of researching VW and V8 heads and not to run low compression.  My focus is on going for efficiency in the head and the flame travel and pressure being applied across the entire piston.

Zach....with a tight deck and the correct cc in the head....you can get good flame travel with an MSD or any other hi energy ignition.  Ignition and spark intensity are important with these type combinations. The 351 motors did not run dual spark and they made great power.

Rick M

I think those 351C guys are SEVERELY biased! ::) I find it very hard to believe that the pinnacle of combustion chamber design was reached over 40 years ago. I am no head guy, but that picture does not impress me. Just look at that intake valve! Another thing the high compression 351C engines used (just like Porsche and Chrysler)... Domed pistons.

If you're limiting yourself to pushrod V8 designs, look at the most modern Neanderthal of the bunch, the GM LS series.
(http://image.vetteweb.com/f/10244041/vemp_0809_02_z+chevrolet_corvette+LS_engine_cylinder_heads.jpg)

:-)..... Fun discussion....but I will not be running a computer, knock sensors, an engine management system or controlled spark timing like all the new stuff. Can't wait to get my together....

Rick M

I wish you luck, and hope you prove me wrong. Too bad we're too late for a before/after dyno test.

Had a VERY interesting trip to the Monterey Historics this past weekend (Thanks again Don and Bill!). Talked to a Ford engineer about the NEW Cobra motor, and it's a 2 valve, full hemi. They tried a partial hemi, (he actually showed me a pic on his personal phone of the prototype) with squish area on both sides, and then re-tooled to make it a full hemi. 11.5 to 1 on pump gas and the full hemi made 10 % more power... And to top things off, I went through the pits to find out what most of the performance motors had for heads, and about 70 % were hemi or domed shaped with little or no squish, both 2 and 4 valve...even a 3 valve...and yes, regardless of age...

Zach....don't have to prove anything. It is already being done. I am not experimenting...I am implementing the hours and technology others have already found out works. Joel....your post confirms what a die hard FORD guy, one of my repair technicians, shared with me.  My heads are being flycut right now and I pick them up tomorrow.

Rick M

Rick, will you post a pic of the final combustion chamber shape post machining? I would be very interested to see the outcome and maybe even apply it to my next motor. I like and respect what you guys are doing - there's always alternatives that work, it just takes people to think outside the box a little. If the hemi style chamber hadn't worked, it would have been dumped years ago. Hell, even my Yamaha Rd500 (Rz500 in the US) two stroke V4 has domed type chambers and that seems to work very nicely.

Your findings regarding cooling and CR are very interesting. Less heat and pinging at the same CR has to be applauded.  8)

Regards, Matt

Matt,

I will take some shots this weekend as I start laying out the parts for assembly.  The chamber design on the first shot of this thread has not changed.  We just flycut the heads more to arrive at the 9.0 to 1 that I want to run.  I am running a .050 copper head gasket on the motor and setting the pistons to "0" deck before the copper gasket. Static compression should end up around 9.0 and dynamic compression around 8.0, based upon when my valve closes fully.

http://www.kb-silvolite.com/calc.php?action=comp

Attached is a great tool that Texas Tom sent to me.  I would recommend using it.  It is a great way to figure out the true compression when valves are closed all the way.  It takes into consideration rod angle, stroke, bore, gasket thickness and inside gasket bore diameter (copper gasket), valve timing and deck height.  I love the tool and have used it setting up my current motor.

Rick M

Yeah Rick, I just used that site to do an actual calculation on my engine.  It is set at 8.3 static and 7.0 dynamic.  I knew that it was just over 8 to 1, but now I know for sure.

Yeah...I really like how it takes into consideration the rod length, head gasket thickness, the actual valve closing and other critical measures.  It really helps dial things in. Texas Tom turned me on to it.  I will use it on all my motor combos now.

Rick M

Dynamic compression ratio changes through out the RPM range and the calculators have no way of knowing your true VE at a specific RPM
( unless you have this info from testing and can plug it in)  so unfortunately those calculators don't turn out to be that accurate. Still an OK tool but I wouldnt put too much faith in them.

We use Kiestler in cylinder pressure transducers  in all our dyno cells at Westport but for the average tuning shop they are quite expensive.
about 3-4 grand per cylinder with amplifier....
This is really the only way to get the actual dynamic cylinder pressure.

We now have 13  test cells at the vancouver location including 1 CVS dilution tunnel  that cost a cool 4.5 mil.  :)




 

Rick, thanks for the link  8)

Very useful tool that gives us a better understanding of true CR and for free!  Playing around with specs; It's interesting to watch your CR bleed off with more cam overlap... That's why 'big' cams need big CR.

Less heat shows that there is less energy produced... And that is great for the street.

The more alu you remove from the head the hotter the rest of the remaining alu will be, I believe.

I used to believe that valve unshrouding was done to improve flow through the seat, and that you stopped once the numbers dropped of. If you keep going you will in the end have a flathead. I believe that the word hemi comes from how the head looks like after optimal unshrouding of valves (when the valves are close to 45 degrees apart). The powers of the actual word hemi is limited to the marketing department IMHO.

But like its being said, anything can be made to work with enough effort.  But can anything be made to work best
I must say there are some confusing things said in this thread, like a slow burn is not necessarily a bad thing.

I would love to run 911 heads on my engine... But not because they look like hemi's, ....but because they flow like hell.

Agreed, especially since little context has been provided to validate the opinion. A slow burn isn't necessarily a bad thing if your timing has been optimized with respect to that characteristic, and the rise in cylinder pressure/heat does not ouptace the flame-front and cause detonation. A slow burn isn't necessarily a bad thing due to lean, high AFR at partial-throttle cruise. Too many generalizations...

Hey JHU....nice blog you have running.  The intent of this thread is to get people thinking. There is no "ONE WAY" to do everything.  If that were the case, there would be one car manufacturer, one home builder, one plastics manufacturer, etc., etc., etc. .    Innovation is the result of trying different ideas and still achieving results.  Having driven dual carb motors on the street since 1970, I am always looking for new ways to improve my street motor and street-ability.  There are a lot of different ways to achieve a desired result.

Rick M

Rick I am just catching up having been away for 10 days,but something I want to point out that i am sure you know but is a little missleading

you are not running 0 deck,you are running 0.050 deck if your copper gasket is 0.050 and you set the piston at zero with the top of the cylinder,
some may not understand that from what you wrote,and tight deck is a relative term,for me 0.035-0.040 is "tight deck" but everyone has there own ideas on that

You will need 58-63cc in your heads with that 0.050 deck in a 2276 to get 9-9.5/1 compression which is still pretty large,are you thinking of using dished pistons as well in this engine?

I too am interested to see you final chamber shape after you have flycut it down,dont forget the camera before you assemble the engine :)

cheers richie

Richie,

I have 62cc in the head at this time. Still working on it. Not done with the final shape.  I like those dished Weisco's you show on your website.  :-)

Rick M

Rick, how much have you flycut the heads so far? I imagine your heads pre flycut must have been in the 72cc-ish range? What was your deck height and compression previously?

Another shot of the chambers after polishing. Not quite finished yet. One final CC to determine if I at my target figure after I align the barrel seating area with the cylinders.

Rick M

nice! what tools are you using for this? ie what grits ect?

i'm still pondering my chamber design, i've just unshrouded to the barrel and blended it, removed any sharp edges where the seats were cut and its looking pretty open to me....

(http://i40.photobucket.com/albums/e222/andy198712/8f06e307.jpg)

I use some carbide cutters for some of the blending, then move to 60 and 80 grit cylindrical sanding cones used on a 13,000 air powered die grinder (with 1/4" arbor for the cones).  Will post some pictures tonight. I then go to a 180 grit cone to get the majority of all sanding marks reduced so my polishing compounds and buffing tools do the rest.  The intent of smoothing the machined and cast portions of the chamber are to create a reflective affect where the head is not a heat sink. It is a less expensive way of doing this than having space age coatings applied.  If you have the money, the thermal barriers are worth it.  I am doing it this way to test it out.  I have done both.

I still have a little more shaping and blending to ensure that the top of the piston as it slams toward the combustion chamber is not pushing against any steps or sharp corners. Will post shots when the final chamber and CC work is done.  I also polish the tops of my pistons.

RM

http://en.m.wikipedia.org/wiki/Hemi_engine#section_2

limbach aircraft heads have something like a semi-hemi chamber

Thanks for going over that for me bud!

did you notice any benifit with either the coatings or polishing? how did they look when torn down?

Thanks

Andy,

The intent with both is to reflect the heat into the combustion area and out the exhaust rather than have the head absorb it as a heat sink. However, being an aircooled head, obviously the head will dissipate heat through the surface areas of the fins and the fan will (if working correctly) blow it off the head. The open chamber design is not just for lower compression as some seem so stuck on thinking.  Other improvements I know work and I am working to achieve is to reduce heat retention and have it help the combustion and torque produced. 

Will show the results when the motor is back together. Again, I am not trying to be an 11 second street car.  Just a car that can drive anywhere, any distance, in any weather,  any time.  Already did it with one combination during the early days of the BERG CRUISE to Detroit (1997).  Working on a variation of that with this new motor.

RM

Cheers bud, i agree on your points, and i guess the coatings help get more heat out to the exhaust instead of soaking into the head, longer life span, happier engine.  i have similar goals to you, reliability close to a stock engine

Spent Saturday finishing up the final polishing on my combustion chambers.  Will be running a .04635 copper gasket between the heads and the barrels (running "0" deck in the barrel).  With my combustion chamber mods and cam grind, will be running a FLAT TOP (not dished piston) on this redo. Ended up with 65cc in the heads.

From here...the assembly begins.  Running a 106 lobe center cam with .473 lift at the valve.  Intake valve will close at 35 ABDC to achieve the dynamic compression we were looking to hit.   Cam grind was ground to help me achieve my driveability goals of coming off idle to 5000-5500.

We are calculating for 7.6 dynamic compression and 8.7 to 8.8 for the static compression and running on 91 octane pump gas. Primary goals are driveability, improved bottom end and better cooling.  Top end after 5500 is not a consideration for this combo as the cam design will simply not achieve any measurable increase in horsepower after 5500 to 6000 rpm.

Rick M

Finished the chambers on my street heads, polished the crowns of the pistons and dialed in the cam this weekend.  Now it goes back together. Will be interesting to see what was accomplished towards gaining more torque down low.

Rick M

I'm liking this polsing lark allot.

Am I right in thinking it would be so good in turboed engine?? Getting more heat in to the turbo should help with the turbo spool earlier.

How soon would you expect any build up of the waste products of combustion on the finish Rick, and how would that diminish the effect? Do they need to be redone every so often or something?

The heads will carbon up relatively soon.  Polishing helps tighten the material (get rid of porosity). It is not nearly as good as a ceramic coating but a poor mans way to make incremental improvements. My main objective was really the shape of the combustion chamber for quench. I am running a .0465 copper gasket on top my cylinders with "0" deck in the bore.  Just finishing final assembly of the motor this week. Completed cam degree exercise and checked all clearances last week. My cam has 2 degrees advance built into the cam. Running 478 lift and 218 duration at .050 with 106 lobe centers.

Rick M

"Top of the page" cam, Rick? ;)

Top of the page...NO.  Had the cam ground for what I am trying to accomplish rather than taking one off of any page or out of any catalog.

Rick M

218*@.050 is a typing error,  right?   With that little duration,  I don't care how much overlap you machine the cam with,  at 8.8to1 I would think it would detonate.

It was a joke, Rick. A joke.

Zach....not my first rodeo. I get it.  :-)

Rick M

Keep up the good work Rick ;)

An interesting read.
I first started using the Berg semi-hemi cut in the late '80s. I've never regarded it as a performance enhancing mod, more a quick and easy way to lower compression ratio by increasing combustion chamber volume. Before that, the only way to increase chamber volume was to reshape the chambers by hand - a laborious task, especially if you're looking for an increase of 4cc per chamber or more - involving hours of die grinding cc-ing, more grinding etc etc. In the '80s and'90s I was building street motors with much lower CR than I use nowadays, plus the fact most heads suitable for street use back then had smaller chamber volumes than the heads we have nowadays (eg 044s). Short of running a ton of deck height (strictly verboten) or dishing the piston, finding more volume in the chamber was the way to go to arrive at the target CR.

One of the clues as to why the semi-hemi cut combustion chamber doesn't perform on a par with a well designed wedge type chamber can be found in the instructions Berg provides with the semi-hemi tool: he mentions having to run more ignition advance to achieve best performance. As a general rule you'll find less efficient chamber designs require more advance i.e. it takes longer to burn all the air fuel mixture so you have to start the fire earlier. Looking at a modern engine design, a typical four valve per cylinder layout with centrally located spark plug will run a max advance of around 20° BTDC. If you can achieve best results with less ignition timing, you have less pumping losses and therefore more power delivered to the flywheel.

On most of the street engines I build nowadays there's no need to go in search of extra chamber volume - partly because I run higher CR than I used to but also because the majority of aftermarket heads start out with larger chambers than I had to work with 20+ years ago. A few weeks ago I dug out the semi-hemi cutter for the first time in years. The project was a mild 2110cc bus motor, with stock heads, Engle 110 and a pair of 40IDFs. I start with a fixed deck of .045" and then calculated the required chamber volume. The semi-hemi route was the quickest and easiest way to get where I needed. On the dyno I started with an initial max advance of 32°. Increasing timing by a couple of degrees at a time to find best performance. I finally settled on 38°.  If I left it down around 30-32° I was giving up power and torque, plus the exhaust gas temps were running higher.  I was perfectly happy with the end result and don't see any problem running semi-hemi heads on an engine of this type but for a higher performance orientated motor I'd always recommend a compact wedge chamber with large squish area and run a tight deck.

rick m... you mentioned you were reducing surface area by using the semi-hemi chamber and further reducing it by blending in the sharp edges. If I understand you correctly, in fact you're doing the opposite and actually increasing surface area. By converting all (or most) of the flat squish/quench area into a concave form you have more surface area than you started with. Now more of the heat energy from combustion is absorbed by the head instead of acting on the piston.

On the subject of hemi cutting and then flycutting the head to get rid of some of the extra volume you've created....
A dyno test I carried out many years ago threw up something odd. I'd previously built a normally aspirated 2165cc race engine for a customer. He raced for a season, then brought the engine back for a refresh. He'd also acquired a pair of Super Flow heads from another racer that had been intended for a turbocharged engine. They'd been semi-hemi cut, with all the edges carefully hand-blended in. A really nice pair of heads but the chamber volume was HUGE! I can't recall the exact figures but CR would have been down in the 8s on the 2165cc n/a engine. I flycut them as much as I dare in order to increase CR. On the dyno all was fine until it got up around 6500rpm. At that point the engine started making this horrendous noise. It sounded like a box of firecrackers going off. Pushing it beyond 6500rpm towards 7000rpm and above the noise would go away. At the time I didn't figure out exactly what it was but subsequently came to the conclusion there was something weird going on in the combustion chamber as a result of the reduced height semi-hemi cut i.e. combustion efficiency was going haywire.

I fully accept semi-hemi heads can work just fine on a relatively mild torquey street engine - I've done it several times. But if you're building an engine where optimum performance and efficiency is the goal, I don't believe the semi-hemi approach, at least as I understand it, is the way to go.

Rick and Joel, hope you don't think I'm dissing your findings. If you're achieving good results in the real world with your updated version of the semi-hemi I can't argue against them and appreciate you sharing them on here. Just thought I'd chip in with a little of what I've experienced. Look forward to reading more of your reports.

All the best

JM

 Just to add to the use of the semi-hemi chamber design in racing, the Salzburg Rally cars (Austrian Privateers) used the semi-hemi chamber with great results. It worked really well on the highly-tuned 1600's with twin Weber 46 IDAs. Reading the info on the cars, the team found it worked for their given application. Unfortunately, they don't go into great detail as to why it worked much better, perhaps it has something to do with the duration of the events and how long the car would be subject to full-throttle and heavy loading. It would be really interesting to find out their specific CR...

http://www.1302super.com/page35.html

Thanks JHU! 9.1 CR and 120 hp for a 1600 is pretty darn respectable! And all through 39mm intakes and 32mm exhaust valves...
They were very reliable cars, too  ;)

(http://www.rallybugs.com/images/Albert/heads2.jpg)

More than respectable, especially considering it was back in the early '70s!

A quick bit of maths.... assuming a deck height of 1mm, it takes a chamber volume of 43cc to arrive at 9.1 CR (flat top piston).
They'd've had to heavily flycut an 040 hemi chamber to achieve that, which brings us back to Rick and Joel's method and therefore contradicts what I said above!  ;)

There are more than a few engine builders today who could extract superior performance from the same configuration - but that's only to be expected with the benefit of 40+ years progress  ;)

Thanks for contributing John! Are you up for a bit of guessing? What would be a possible gain of removing the squish area like the salzburg boys have done. And would the engine run cooler with squish?

If all the VW crowd can venture outside the VW world long enough to study what V8s have been doing, along with cam timing (lobe seperation, when the intake closes, etc,) you can quickly get an idea where the gains are found.  Again, I have stated repeatedly in this threat that I am NOT trying to be the quickest car at the quarter mile.  I am focusing on where a street engine does most of its driving.  Do the RALLY cars that used the SALZBURGHEAD run at 7500 to 9000 all day long or do they run more around 3500 to 5000 during a race?

I am using the head design in an entirely different application than Joel. I do not plan on taking my particular combination much over 5500, because with the cam I have, it won't go there anyway. I am focused on making all my power between 2000 and 5000 rpm.

John, chamber volume and surface area are two entirely different subjects. I will post later when I return home from work to give the example. I've been at this a long time too but 99.9% of my involvement in the hobby has been street driven cars that do most of their driving between 1000 rpms and 6000 rpms. 

Rick M

Rick, the Salzburg cars made peak power at 6k and were reved to 6,700 rpm on occasion.

John, I guess it's just proof that there are plenty of ways to skin the same cat. Good to see you post again, last I heard you had disappeared down the barrel of a giant zoom lens :)

Regards, Matt Keene

All Torque....

Here is another shot of the Salzburg head. Look at my head by comparison....your comment about the 6000 to 6700 rpms is making my point. My cam is designed to stay a little lower in the peak torque and power band.

Rick M[attachment=1]

Rick, we're not on the same page with regard to what constitutes surface area of the combustion chamber. I'm not including the squish area when I'm referring to the wedge chamber because when you run a tight deck, practically the entire air/fuel mixture is being 'squished' into the bath tub. With a deck of approx 1mm (.040"), the clearance in a running engine is getting close to zero, taking that whole area out of the equation. A good analogy is to picture the intake mixture in the chamber prior to ignition as a pile of dried up autumn leaves. With the tight deck squish/wedge design you've swept them all into a compact pile. In a hemi chamber they're spread out over a larger area, with the surface area of the chamber now consisting of the entire bore area. This is why you need more ignition advance on a single spark plug semi-hemi VW if you want to build maximum pressure on the piston at the optimum time.


I'm all for looking at alternative engine designs to see how the 'other guys' do things and wondering if any aspects of their technology can be transferred across to our VW aircooled engines. BUT... you have to take the whole design into consideration. For instance, in a true two valve per cylinder hemi motor the intake valve is canted as well as inclined. The advantage of adding cant is that the head of the intake valve moves away from the cylinder wall the further it's lifted off the seat. This greatly improves flow compared to the shrouded VW inline layout and is the major reason hemis make good horsepower (lots more leaves to burn). Accommodating the canted valve layout is the major factor in dictating the hemi chamber's design - not the other way round. It's no coincidence many hemi designs opted for twin spark plugs to counteract the larger surface area of the chambers. To be fair, the typical V8 hemi has a much larger bore diameter than the average performance VW, so the issue of extended flame travel in a semi-hemi VW chamber won't be as severe. My point is it's easy to look at a design that appears advantageous and assume the gains are the result of a single component. That is very rarely, if ever, the case. A successful R&D engine project is usually the result of numerous incremental changes to a whole variety of parts - which based on what you've written so far, sounds like a process you're already going through.

Sorry if I'm coming over too pernickity.... I'm enjoying the conversation! Looking forward to your upcoming reports.

Here's another example...My PUMA motor is 72 x 85.5,(1654) 35 x 32 ported and polished, hemi chambers, 44 IDFs, WEB 122 on 108 centers, 9 to 1, 3 step header,  makes 115 hp and 108 torque. Purrs like a kitten, and goes to 7,000

Hey Rick,  is that 218°.050 number correct?

Taylor...NO.  You are the only one paying attention.  :-)  Just thought I would throw it out to see if anyone thought about it.  My cam is at spec'd out at 236 at .050.  The lift figure was correct.  Lobes are ground on 107 centers.  Good to see some people are thinking and paying attention. 

John M.....we have a lot of really schooled, knowledgeable people on this thread.  Great to see all the interaction.  Like All Torque stated....there are a lot of different ways to skin the cat.

Believe me, I understand the bathtub chamber, canted valves, etc. The ford 351 motor, which I believe I posted some shots of the chamber, had an open chamber design.  I totally agree that the larger area of a hemi style chamber would benefit from a twin plug motor.  My 3.6 Porsche twin plug 911 was an incredible motor. It made so much torque with the 911 hemi chamber and twin plug ignition that it would spin my 320/45x18 Continental Rear Radials from a rolling 30 mph in first gear.

I am playing around with the whole engine dynamic related to cam, carburetion, compression, ignition, etc. The Salzburg head, before someone else posted it, started making me think about some of this. Those motors, I believe, were set up close to 9 to 1 compression from what I have read about them. I would love to have the cam specs/valve timing on them.   It is interesting that they ran IDAs on relatively small motors, gutted the stock exhaust system and ran it.  I am interested in trying new combos taking into consideration a lot of different factors.

I will definitely post my results when I get the motor back together and even click some video to post once in the car, cam broke in and tuned.

Rick M

Hey Rick,  I'm not trying to start a fire storm again, but I am wondering whether you really feel 236*@.050 is enough to offset your 8.8to1 CR?  I, obviously do not have the @.100, .200 and .300 numbers but that really seems low.  For all I know it could have a huge number under the curve.  I know that you plugged the intake closing numbers into the Keith Black calculator and it says 7.6to1 or whatever, but that doesn't take into account volumetric efficiency (VE).  Not getting into VE here but for posterity and the search engine a quick insight into it.  As RPM increases it is the ability of an engine to fill the cylinder to its mathematical potential and sometimes beyond that calculation.  What I am getting at is with your cylinder head port modifications and your choice of such a small cam are you not hindering your engines ability to breath? And furthermore aren't you worried that without the ability to breath the potential for detonation increases? Running duration is different than static duration and unless it is hydraulic it will be even smaller when running.

Taylor.....Hmmmmmmmm.....Did I hear you say hydraulic?  :-)

RM

More progress.  Short block together, sump on, new JBE oringed sump plate. This week pistons, heads and rocker assembly go on.

RM

Had my Sil Modesti aluminum motor breather powdercoated for easier maintenance, plus cleaned up the copper header exhaust gaskets in preparation for assembling the balance of the motor. Moving at a little faster pace now that it has cooled off.  Morning and evening temps are no longer the killer 105+ temps.  Nights and morning are now in the 70's which is car project weather.

RM[attachment=1]

Hello.
Joel. Such an engine oughta pull those #´s anyway. The 122 is an aggressive lump of steel.

WRT the Salzburg engine. I seem to remember that the reason for them using the gutted stock exhaust were regulation in the class or something like that. Next, I have recently been involved in a supercharger project where we also ended up using a gutted and modified stock muffler, mostly to keep stock appearance and to fool the enemy. Now, I´m NOT saying that we could not have pulled even higher #´s with a good  4-1 header. But the performance and torque numbers of this engine surprised even me. But on the other hand, the peak power on this particular engine is also at 5100 rpm. Quite some way from 6700 rpm.
I do remember being said that the reason to them staying at 9 - 1 CR was due to the fact that they could not keep head temps in check on longer stages if elevated more than that, partly due to them having to run the stockish muffler.

Going back to the cylinder head design. One of the things I was looking at when I was working  with the SH solution was how complete the burn was. And I was never able to get the ppm numbers down to what I thought was decent. They were always 15-20% higher than the same engine with a bathtub (!) good word  ;D design. That is also what I see on the 616/356 engines. They have to run horrific high numbers in CO and ppm to run decent. It could be really interesting to find out how that looks in a more "modern"  SH chamber like Ricks or Joels version.

The use of twin spark ignition in such a chamber would change everything. I have noticed a couple of 616/356 engines that runs twin spark. And suddenly they can run super clean emissions and idle CO can be cut in half, O2 numbers at WOT can be reduced along with a temperature drop in the heads and finally the power increase for these semi quick engines were 6-10 hp. Also look at the Alfa Romeo 1,8 & 2,0 engines. They came out with T-spark back in ´89. Compared to the sgl. spark version they pulled 10 hp more AND equalled Euro 1 emissions (Cat 1 to others) The increase in hp comes (off course) only partly from the improovement in the burn, the reduction in pumping losses and also the fact that the engine now can run typically 1 digit higher CR with out detionation plays a significant role. Now, the Alfa cylinderheads have a ball/dome shaped chamber with the plug right in the middle of the top. The addition of an extra plug all the way towards the side of the chamber on the exhaust side, (on the 16V models just between the valves in the side of the chamber) and firing it 2 degrees early, that way pushing the the rest of the unburned mix to the center of the chamber for a more complete and efficient burn.
On a bathtub type of chamber we more or less know the advantages of TS due to some people around the World have taken the time and effort to seriusly and scientificly explore this. Limbach does it on type 1/WBX heads, but that is from a safety point of view first over efficiency. From a leighman´s point of view I would expect the efficiency and emission numbers to improove in about the same rate as with a conventional chamber, leaving only the cylinderhead temperature issue open. I really have no idea whether that would improove the same way too or not. Theoretically it should, due to the lesser pumping loss alone, but that is pure speculation.

T

Torben,

I will let you know on the CO numbers and emissions after mine is up and running. I will put it on the wheel dyno at Competition Engineering to test it out as we dial it in.  I too am in the hunt for lesser cylinder head temps living in the arid, hot Arizona desert.  We will see what the outcome is in weeks when I have it all back together.

Rick M

No pictures yet but long block together, rockers on, engine tin, exhaust and other bottom end pieces going together. Was hoping to have ready for VEGAS but too much going on at work, etc. Will post pix when in the car.

RM

Long block done. Rocker geometry done. Returned to using VW valve covers with the stock bales. Set them up with 1/2" tubing for my breather hoses. There are some opinions that the heads cool better with the stock valve covers vs. solid aluminum ones. I included a shot of the intake ports.  Will finish up the top end this weekend. Slow but steady progress.

Rick M

Can't wait to see the results of this.

Won't be long now. I have to button up the motor this weekend as I have a show to go to on the 3rd of November and the following couple weeks as well.  Will post shots as things start going back in the chop top.

Rick Mortensen

Getting close. New trans mounts in, new cross-shaft for throwout bearing, long block together, car cleaned up and ready to start bolting things together and put the motor in this week in preparation for BUG-O-RAMA weekend.

Rick M

Digging that pulley bolt ... Where'd ya find that one, Rick?
TxT

Have owned it for years Tom.  Getting close to start up day. Will shoot some video of the car when done and running. I ended up at 8.7 SC and 7.4 DC.  We'll see how things work with my heads and pump gas.

Rick M

The open chamber head motor lives. It is in the car, running and boy is it fun. It has a ton more bottom end power than it had with the K8 cam in it. All the power is from 1500 to 5500 where I do most my driving. Bottom end torque improved dramatically.  The final numbers on compression were closer to 9.0 static and 7.6 dynamic.  I am trying to figure out how to load some video I took and will post it later today.  The changes have made this a much more drivable and enjoyable motor.

Some of the things I did on the heads was reduce the spring pressure too. I toned it down from 165 on the seat to 140. Backed the pressure at total lift down on the nose from 320 to 280 as I will not be drag racing the motor and taking it over 5500 to 6000 rpms. All these type reductions will help on cam and valve train wear. I use Valvoline VR1 oil due to the ZDDP content along with a ZINC additive during the 500 mile break in period. Put over 120 miles in it yesterday with a few 100 mph road blasts.  Has incredible pull in 4th gear from 55 to 95. Surprised a couple V8s yesterday.

Current jetting in the IDAs is 60 idles, 165 mains and 190 air. I was able to back down the timing from the 34 degrees I was running with the old motor combo to 30 degrees.  The motors seems to love it. The tighter quench area has really livened the car up and there is NO DETONATION.

Will try and get my motor video up later today. The motor now recovers from doing short blasts and runs back at the 180 degrees I was looking for.  I drove it to CE today for their pre-Bugorama open house. Drove very smoothly, no flat spots or hesitations.

RM

RM

Here are a couple shots from the CE open house .Still working on the video upload.

Guten Worken mein Herr!

Thanks All Torque.  Now I just have to figure out how to get my wmv file small enough to post on Youtube or this site.

Rick M

     Rick what happened yesterday did you forget to stop by the party and also I was expecting to see you at Bug O Rama today.

Frenchy

Frenchy,

Wasn't feeling too well yesterday after I left your place and decided I'd better return home. I ended up in bed with the Flu all day today.  Sorry I missed you guys later Sat night.  I stayed up half the night on Friday getting the chop running and paid for it the rest of the weekend.

RM

The Salzburg Combustion Chamber Motor Lives! I posted the short video I shot here for those following this thread too.  Will have more information later as well.

http://www.youtube.com/watch?feature=player_embedded&v=oCQkmowJBKs

Rick M

Hey Rick. I watched the vid and the motor sounds great! Good work dude ;)
Car looks very cool, too!
Regards, Matt

Thanks Matt.  I guess those Salzburg head guys learned a lot of things that worked over 30+ years back!  I will be playing with the tune more but for now....it really runs nice! Very smooth powerband right where I was wanting it.  I guess all the reading I did on cam timing and head design wasn't so far off.  I studied a lot of V8 head designs and ran with the idea.

Rick M

Here is a little teaser until I can make a better video. This was done with my cell phone and me trying to hold it against the steering wheel while I ran through the gears.  Just for those watching, I have a close third but a stock .89 4th with a 3.88 r&p. Going into 4th gear you can hear the motor rpms pull down a little.  I will make a better video this weekend and post it.  For now, it let's you hear this open chamber head (Salzburg style) and how nice it sounds.  Relatively small cam with 1.45 rockers (FK65).

Rick M

http://www.youtube.com/watch?feature=player_embedded&v=mup_kkzvCkw

Who is a good source for WEBER jets.  I need to buy more for my assortment of Mains and A/Correction jets.

Rick M

Aircooled.net

Art at ACE.

If you are looking for the crank pulley bolt that is on Rick's motor. We make them at Competition Engineering out of stainless and they are .250 longer than stock
and you don't need a washer. Rick is a good customer of ours and sometimes he forgets where he buys his parts   :) :)

Thanks
Mike and the C/E crew

Mike....How can I forget? I can drive to CE in my sleep.  Just about ready to drop off the crank, flywheel, pulley and rods for Anne's buggy motor to be balanced.  Need you to check the valve job on the heads I am using too.  Will stop by next week.

RM

HAHAHA! I used to be a parts guy for years. I had to remind friends where they got stuff from occasionally too!  :)

Just read the whole thread. VERY, VERY cool Rick, especially since I now know my cam/comp/flow combination should work well, since you've just made everything (size of motor, port CSA/valves, chamber, etc) a bit bigger then tested it for me.
Thanks for that.  ;D My temps and climate are very similar to yours, just a bit warmer, both summer and winter.

I hadn't considered a "semi-hemi" as such, my own experience on V8s both as streeters but also drag street sedans is that the Ford 302 Clevo closed chamber works better than the open chamber, and the old Holden slant wedge chamber does the same compared to the newer open chamber Holden heads, so I hadn't really considered anything other than a blended very small chamber. I did however, want to modify the chamber shape a bit, I had envisioned a similar but smaller chamber shape and blending, but out on the plug side, and by using a screw-in insert into the spark plug threads and 10mm plugs also pull the plug back out of the chamber by 5-10mm. It's all in trying to centre the plug and "squish" the mixture into it, but by avoiding if I can doing any welding on the chamber or the heads. The "bathtub" would end up looking more like a "heart" with the plug in the tail.
Just to make it even more interesting, the chamber will need to CC out at about 48-50cc.

Second opinions, or am I overthinking the thing.........yet again!

I don't believe you are overthinking your ideas. I spent 3 months thinking through my cam selection (lift, valve opening and closing numbers, overlap) the size of the ports, the size of my venturies in my 48 IDAs, chamber design, exhaust size, etc.  It all worked out just as I wanted it to.  I like to take the time thinking about where I plan to drive the motor, what I am using it for, etc. Otherwise you end up building something that is an irritating experience.

Rick M

Yeah, that sums it up. My aims are similar to yours, hence the similarity of parts chosen.

I pick the rev range I want, then the duration to suit, then IVC and overlap to suit comp and octane, then the smallest ports and valves I can get away with to feed it all. This is for a streeter, and I don't have any traffic lights within 200miles to encourage me to go bigger!  :D

Head chamber shape, and how the biasing suits the bowl entry and seats is where I'm at now, so your thread is right on time.

Where in the hell (literally) do you live?? Not many places hotter than here in Phoenix.

Gday Zach.
It's not that much hotter really.
I live 200 miles north of Perth WA. It's about 100miles from the coast and inland, and at 29*South. Anywhere in Oz that's further north than 30*South, and further inland than 100 miles, has similar temps give or take a couple of degrees. During the summer, it's mostly mid-20s*C overnight, and mid-40s*C during the day. I leave work at 2:30pm, and usually ride into a 20mph headwind/crosswind and the mid-40s.
Plenty of places hotter than here though. In the Gulf (Iran/Iraq) I remember the temps getting over 50*C (which it does here a few times a year) for 2 weeks in a row.........125F every day, phew!
Anyway, my little 1700-ish motor has to push my Superbug through the wind and up and down rolling hills in this for an hour at 65-70mph, hence the focus on the little details of deck height/chamber shape etc.

If I ever moved to the US for work, I've already told the "powers-that-be" that Arizona and New Mexico is fine thanks! Just like home!

Just watched the clip of you getting out of your garage Rick........
Damn! That does look like around here!
 :D

Yeah...I imagine that where you are and our climates are very similar.

Rick M

rick great build thread( i just read thru all 7 pages )  and way to show people not to be so closed minded ! the videos rock !

Thanks Draven898.....Took me a few months to pull the motor down and make the mods but the driveability and performance of the motor on pump gas was worth it.  Will be enjoying it this spring. Now I need to get my rear deck lid and apron painted so it does not look like such a project.  :-)

Rick M

Rick,  try pierce manifold in gilroy ca. 1-408-842-6667
They have almost every weber part available

Took the chop out tonight for the Last Supper of the 20 year old WOLFSBURG REGISTRY VW CLUB.  This is one of the oldest VW clubs in Arizona and it has a long running tradition and has had many great members.  Will miss the club but will still have some great and lasting friendships from our association with them.

The chop ran awesome. Smooth, driveable 2275 torque and horsepower...right where I wanted it.

Rick M

I have been following this thread from the start and first of have to say hats of to Rick who has gone against the main stream thinking in the vw community and actually let us bullying him for what he does and believe. ;D
Now a days we are talking much shit about the old hemi style heads, but I think that is mostly because not many people know about those few good things there is with doing the hemi style.
First of, when the hemi style came to America the fuel prices was low and fuel consumption wasn't on anyones mind.
At that time power was everything and to get more power they started pushing the compression higher.
But with higher comp you always get the risk of hotspots and self ignition, and here comes the hemi style into the picture.

When building an engine with the hemi style the bigger bowl will lead to a more balanced air temperature in the chamber so there is less change of self ignition.
So this way they could get higher comp on the same octane, and thereby more power.
Also known is that the good old American engines are low rpm engines and thereby flame speed is not an big issue.

But now a days with the fuel prices and climate changes we care more about the fuel efficiency and also VW engines are small high rpm engines.
This is where the hemi style is rubbish, the hemi style gives a bad concentration of the mixture and so a lower efficiency, also the flame has to travel further, something that is very difficult at higher rpm. So the solution is to introduce squish, this gives a better concentration of the mixture, and much more turbulent air.
That gives a faster flame front, faster explosion, higher efficiency.

But as we see in this thread, not all people is known with the good and bad things in the different designs and thereby judge by what they have heard from other people.
I shouldn't need to say it, but of course there is many more factors that I haven't mention and probably many more that I don't know about.  :)

So for a low rpm engine where torque are more interesting than MPG, this may still be a way to go.
I wouldn't do so, but I'm not an American. ;D

Dalland....

My motor's rpms will not do much past 5000-5500. However,  I knew that going in and that is where I chose a cam design that would work there. Tuche' on your understanding of how the squish and the turbulence work with this chamber design. I have one other advantage...larger valves (intake and exhaust) are allowing more air/fuel at a lower RPM.  Ever looked inside a big block Chevy intake/exhaust port and the size of their valves?  Guess what? The valves on a 454 and the ports are pretty big but the cams are not.  They build truck motors for TORQUE and not drag racing.  The idea of making more torque down low is nothing new and it is very drivable power.

I followed the cam advice of a Chevy engineer who suggested smaller overlap and closing the valves sooner. He stated dynamic compression would work with my combustion chambers and the size of the valves and air flow at lower RPM would offset the smaller lift and help make fun, drivable power down low.  GUESS WHAT?  It worked! Again, am not trying to get into the 100mph club or have an 11 second street car. However, I can tell you that for stop light fun and drivability....this combination has been a lot of fun. It is not a slouch. I just have to shift at a lower RPM to stay in the power band.  I do not need killer spring pressures which means less wear and tear on the cam and valve train. I do not need to buzz it to rpms between 5000 and 7500 to feel it pull hard.  I just learn to drive it a little differently.

Rick M

Have you driven it enough to get a feeling for fuel mileage ? I'm interested in doing something similare to what you' ve done.

Brian....to be honest with you I have been flogging it so much it has not been a good way to determine mileage.  I will drive it a little more conservatively and then give you an idea. It is such a fun motor....I guess I have not thought much about the mileage factor.  I will be doing some road trips soon and will give you an idea after that measure.

Rick M

Hey Rick, I have no experience about the old big block engines, mostly because I'm only 22.
But I am lucky to have a good friend and teacher that must be one of the smartest engine developer in Europe.

He told about the amcar thinking about valve design and that they believed that slow rpm engines don't have the same "problem" with dynamic compression and that the inertia of the air will work against them and not with them as in high rpm engines. So thereby the used large valves to to have "all" the air it need ready behind the valve for the down stroke.

But then again, what is low rpm when it comes to the inertia of air?
It would be interesting to see tests from different valve size and designs on low rpm engines, but i will still believe that small valves and high air speed is the way to go.
When my teacher was working for Porsche in the eighties this was one of the things he was working with, and he is also a strong believer in small valves...
And than it is the question of the air/fuel mixture quality when the air speed slows down..

But please do some mileage tests, for what its worth my 2275 with 42mm valves and much squish runs 46 mpg on longer trips.

46mpg?!?!?! Blimey! What's the details??

Yes what is low rpm? I'd be tempted to say most car engine are low rpm when compared to rpm's spun by bikes...?

Hey Andy, no fancy parts just a good tune. parts listed here: http://cal-look.no/lounge/index.php/topic,18639.0.html

To take an example from my new workplace, the Rolls Royce boat engines that are built runs normally at around 800-1100 rpm and they use as small valves as necessary...
Some of the reasons are already mentioned but it is also a thing to know that big valves are hotter valves because the seat area is the cooling area (yes also the stem), this is also one of the reasons that all car engines went from 2 -> 4 valves per cylinder, this was also around the same time as leaded petrol disappeared...

Dalland....

My intakes are 42 and exhausts are 37.5. When speaking low rpms....we are not really that low when you consider most diesels are truly the low rpm motors.  My motor runs great between 2000 and 5000 rpms. What kind of cam grind are you running?  I am curious about the 46mpg.  The best I achieved so far was about 33mpg on a 1915 I built with an engle 110 in it and dual 40IDFs.  I could have achieved better had I put my 36 Dellortos on it.

I can only go by what I know and that is how the car drives and performs.  That is my test bed. I will have to mount my video camera in the car and take it for a drive to illustrate the driveability and power down low.

RM

You can't show drive ability one a video, dyno that shit and we know what you got. ;)
(well I am not the guy to talk since since i still haven't tested my engine)... ;D

Camshaft is a FK-8, all specs is in the link before..
As your topic name suggest, this is my road trip engine as I have been all over Europe with it and my old caravan. ;)

I don't plan on spending any dyno time with the motor. In the 43 years I have been doing this and all the different combo's I have run, I had a pretty good idea what I wanted when I started.  I could careless about posting a dyno figure.  I was building for torque and not hp readings.

RM

For what its worth, the dyno measures torque.. ::)

My thought exactly! Can't get hp without it ;)

I rekn torque is measured best by the bum.  ;D

If you're cruising along at 100kph in top, roll up behind a slow roadtrain doing 90kph, sneak out a bit to check it's clear down the road, then still as a top gear roll-on, PUNCH it......
.......that's torque.

If your new motor is doing 140kph at the front of the roadtrain instead of 130kph that the old one would do, you have more torque.
Simple really.
 ;)

Dalland...
I've been around plenty of dyno's. Just stated I was not intending to dyno my motor. Not necessary for what I am doing.

Good comment modnrod. :-)

RM

Drove the chop to Frenchy's pre-Bugorama open house last night. The trip was exactly 100 miles from the QT gas station and back. Check the mileage.  4.03 gallons = 24.8mpg with my 2275 and I was not driving it all that easy. Need to go up one jet size to a 165 main. Was running a little lean but otherwise very crisp.  I have over 500 miles on the motor now. Time for an oil change and general clean-up...as well as time to finish the rear decklid and apron with paint.

Rick M

Sounds like its bedding in nicely!
So al in all a nice long distance motor?

Yes...I plan to do some road trips and events later in the year now that it is broke in. Will be taking out the chromoly push rods and going to SMITH BROS aluminum racing push rods.  YES...I did say ALUMINUM.  They make custom ones that you can buzz to 11,000 RPMS!  No hype!  Ray Vallero was doing this years ago in his 912 Porsche VW powered drag car.  He has them in some other motors and I am going to make the move too. Just one more step to helping quiet down the motor.

Rick M

Very cool! One of his tricks, I believe is to drill a small hole in the PR wall near the top to aid oiling of the top end :)

Very true. I did this on my current motor.  Keeps the rocker arm assembly lubed very well. The oil also helps pull more heat out of the head.

RM

yh totally agree, going to do this on my build too :)

what size hole did you drill?

I will check for you. I did two sets quite a while back and I will have to verify the set I did not use and post the info for you.

RM

Rick, I am paying with two motors. One a 69x88 and the other is a 74x92. Both have SH heads.  I like to try that cam in one of the motors. Can you email me the cam source?
Thanks
Merry Christmas!!!!

The cam was an ENGLE K65. Still love it. Very driveable. I run it with 1.45 rockers.

Rick Mortensen

I have just read this whole thing and it explains a lot about the very, very poor set of heads that are on my current 1915.
It was commissioned by a friend from a local builder.

What was received is a over heating poorly built engine.
I am about to pull it apart to rebuild it with much better components.
Due to this thread, I may choose to not sell off the heads that are on the car.
Perhaps one day I will put some time and effort into removing all of the cutter marks and sharp edges.

Thank you for taking the time to post the whole build and not just the start of it.