single-port performance

[andrewlandon67]

So I've been working on building a reasonably high-performance single-port motor and I recently found out that one of the heads I was going to use is pretty screwed up. That got me to wondering if anybody on here knows of any ways to build some more performance oriented single-port heads, or of any that have been built. Just for reference, the motor I want to build is a 2054 (94x74) with a 110 cam, high-strength valve springs, solid rocker shafts, etc. Thanks for any help!

[MC Dyno Don]

Your question is rather vague... can you be more specific...? Do you need 1 head or another set..? or are you asking if your single head can be saved..?

[andrewlandon67]

Essentially I just need a single head, but I was thinking that if I could find or make some large-valve single-port heads then I'll do that.

[Zach Gomulka]

What do you plan on feeding this engine with?
IMO, this is a bad combo. The heads will be a massive bottleneck to the displacement and cam. Even if you use Kadrons (the largest single port carb), the 110 is still too big.

I understand the desire to do something different and/or save a buck, but just get some decent 40x35.5 dual ports and Weber/Dellorto 40's and be done with it. Don't reinvent the wheel.

[BeetleBug]

Turbo the shit out of it! 120cfm x 1 bar of boost (15 psi) = 250 hp. 1 more bar and you have 350-370hp with the right combination of parts. With the right car - 9 second run!

[modnrod]

Hehehehe! 

Single ports work well on other Siamese port motors. Some of our Speedway racers are going back to the siamese port design after years and years of only using individual port heads, they need average power across the range under 6000rpm and Siamese set ups work better there.

Maybe VW single port heads work under different rules. 

[Rick Meredith]

Dyno used to have a notch with a single-port motor in it.

I remember it was a pretty stout runner.

[andrewlandon67]

Essentially I just want to transfer the Kadrons off of my current motor, a 1641 single port, and being as this is still going to be my commuter, I'd love to keep the monster torque of a nicely built single port motor, as well as the reliability of the stronger heads.

[modnrod]

Do it man. Don't listen to the naysayers. If I wanted to go fast I'd still have my To#¤ta TT Supra or the Evo, not a 50 yr old tractor.
I just happen to enjoy old tractors! 

Your 2074 motor with a SP 32mm inlet will support well over 100HP at under 5000rpm if you want, all through stock valve sizes.
Have fun and enjoy it I rekn.

[RFbuilt]

here's some ideas and inspiration for the OP



i used a cheap Empi  ICT  manifold for single ports  welded a 40mm ID aluminum tube on top with a slight offset (outwardsand away from the shroud) 
and ported accordingly...  then  cut up a  new aluminu flanged based on the kadron carb base  and threaded for the studs



and then hacksawed/grinder the remaning  ict flang that is now midway  thru the  manifolds,    a lil cleaning with the grinder is still needed to make it look nice


the upside down view shows  some of the work done



and here  the  inside shot.. well almost inside LOL  ...it now has a nice taper  from 40mm ID  then adjusting gradually to 34mm *ict's old ID  and  the EMPI manifold itself tapers to the SP head's inlet flange type


i havnt run these yet.. but  am building something for it as we speak

[brian e]

Here was my first hot rod single port I built.  It was an experiment, but sure ran good.  It is a 69x88TW, 8.8cr, 10lbs flywheel, and a 40mm DCNF.  Its only downfall was the crazy rampy CB Bigfoot 2208 cam.  It made huge torque, but was super noisy, and I am sure I will need to rebuild the heads now after only 4000 miles.  It worked really good, was a blast to drive, and i couldn't get less then 20mpg with it no matter how hard I drove it.   



I just finished this 1915 single port.  I spent way too much time on the heads.  They are stock valves, but I did a ton of work to the intakes.  I filled the 6mm studs, and redrilled 8mm studs with the same spacing as the exhaust flanges.  I also filled the sealing ring recess, and then milled everything flat.  I don't use a gasket, just Motoseal.  The inlet hole is now 34mm.  I managed to get 123cfm @28" .450" with the manifolds and Kadrons bolted on. 




I also made the new manifolds to match the new pattern on the heads.  I used a mandrel bend and pie cut it the whole length so the manifolds tapper the whole way down.


 It was all a ton of work, and it won't hang with a similar dual port 1915, but I guess its different... It will be going in a buddies '62 11 window.  He wanted vintage looking I guess.  It does run good, and makes good power, but I am pretty sure I wont spend the time to do another SP to this degree. 

[modnrod]

  I managed to get 123cfm @28" .450" with the manifolds and Kadrons bolted on. 
 

WOW! Nice numbers! Well done.

[RFbuilt]

agree good numbers on the head!


and that manifold you did is super nice

can i have one LOL

[brian e]

Thanks guys,
 Like I told the guy who's getting it, I could have whipped up some half ass big valve dual port heads and made way more power in 1/3 the time.  But this is different, and it does have a bunch of power now that I am getting the tune closer.  It raps up really quick, and pulls hard, but goes flat about 5200rpm.  Kind of a short powerband.  I used a 218/119 cam, but should have stuck to around 237° @.050".

I think from now on I will limit the single ports to mild cam 1776's.  It will make a really good daily driver and hills cruiser, but not a hot rod. 

Brian

[Torben Alstrup]

This is a 1776 single port with a set of "my" sgl port cylinderheads on and only 34 mm Solex carbs. Modified a little though.

http://images.thesamba.com/vw/gallery/pix/1194909.jpg

Yes, dont over do the cam. These enginese looove split cams.
Dont overdo the valve sizes and ports either. for a street engine 37,5 x 33 can work very well.

T

[Torben Alstrup]

  I managed to get 123cfm @28" .450" with the manifolds and Kadrons bolted on. 
 

WOW! Nice numbers! Well done.

Interesting that the enlarged inlet dont really do much along with a stock intake valve. I get 120 CFM @ 0,500" and 25" with 31 mm port inlet and similar manifolds.
I did a set a couple of years ago with 37,5 intake valves and a D shaped port inlet, area wise i would say that it is most likely very close to a 34 mm Ø. With those heads I was able to get 135 CFM at 0,525" through welded and reshaped Kadron manifolds. Those heads reside on a 1955 type 1 which is Kadron fed. I have not yet persuaded the guy to come on the chassis dyno (Pity) But I´m positive that the engine pulls very close to 120 hp at 5grand. It is really strong for what it is.

I like messing with sgl ports too 

[modnrod]

I'd like to do a set of nice SP heads, maybe 39 x 33 on an 1750-ish motor. As said above, a really nice highway cruiser with a bit of snap.
Are some of the new castings OK ( http://www.ebay.com.au/itm/VOLKSWAGEN-CYLINDER-HEAD-SINGLE-PORT-NEW-COMPLETE-TYPE1-TYPE2-GHIA-311101353A-/251449732009?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a8b926ba9 ), or is it still a case of hunting for a good OEM survivor to rebuild?

[Torben Alstrup]

Back when I was building the 1914 sgl. port bus engine I have told about earlier, we also tried the 39/33 mm valve combo, but LOST torque below 3000 rpm. and only gained a few poinies in the 4500 - 5300 rpm. area. That was one of the reasons we went back to stock valves and sacrificed upper end hp in favour of much better torque in the 1500 - 3000 rpm area. If it is for a larger displacement and or for a beetle, and you want to see what can be gained, it´s another story.

[andrewlandon67]

Thanks for all the advice, I've been doing some pondering and I am more than slightly intrigued by the idea of making some unique manifolds and using a split-duration can to offset the small intake ports, as well as some good polishing and grinding on the head, while keeping a stock valve size. To all of the single-port fettlers, what would you reccomend for valve train work? I'm thinking about ratio rockers, but if that would negatively impact the power/driveability then I'd rather stick with stock ones.

[Torben Alstrup]

There is almost always a trade off. Single port heads need all the lift at the intake it can get (within reason) which typically means about 33-35% L/D to get enough time area to create a decent filling. On theother hand, high valve llift usually makes the lower end torque suffer a bit. (Up to about 2500 rpm) not major, but noticable. The trick is to figure out where you want the intake valve to close. That plays a key role in making torque, at the same time it affects the rpm power significantly too. nothing is easy  You - could - also just colse your eyes and shot for the best solution you can find on paper. Usually its not that far off.

T

[Steve67]

interesting thread!
I am currently running a 64x83 single port engine with dual 34 PCI. The heads are slightly ported and have stock valves. Cam is an Engle W110, which is way too much for the engine size
I would like to upgrade the displacement in the winter. Do you think 78x90,5 would work with that setup? I imagine a nice cruiser with plenty of torque ;-)

[brian e]

I have now put some miles on this 1915 SP.  It seems to have good power, and decent torque, but I went a little too big with the Web 218/119 cam.  It starts coming on a little late, and being a single port, it doesn't rev super high.  It has a little too short of a power band.  Running down the highway at speed its awesome, and it doesn't mind hills at all.  This is in my heavy '74 bug with a 3.88 trans. 

I think if I was going to build a super solid daily driver Single Port I would do the following.

-74x90.5 1904cc
-Heads in the 120cfm range, similar to what I did on the 1915cc. 
-For a cam, I think an FK41 on the intake w/1.25's, and a w100 w/1.1's on the exhaust would neat.  Not sure if that is even possible or would work, but the numbers seem decent too me. 
-I wish I could cut a 40mm IDF in half.  I am over the Kads.  Too many little issues, and not enough adjust-ability. 
-SDVA
-12.5 flywheel

Maybe I am wrong, but I just don't think anything over 1915cc will be that great with the SP heads.  The cylinders are just too big to be completely filled through the small shared opening without major reconstruction. 

Just my thoughts and experiences. 

Brian

[modnrod]

I had this cam ground up for me, specially for use with the SP heads I had planned.
I'm still going to use it on my DP heads too, but it's still intake restricted as I'll be running a stock-looking intake. I rekn it will be a good all-rounder, although most will tell you to get it ground on 107 centres probably (I'll be installing this 2* adv from card specs).
Split duration, smooth lobes, made to work with 1.4s (on the card the exh valve lift should be .434").........



Contact:     http://schneidercams.com/solidliftercamshafts-18.aspx

[Neil Davies]

-I wish I could cut a 40mm IDF in half.  I am over the Kads.  Too many little issues, and not enough adjust-ability. 

I remember seeing some Formula Vee engines over here many years ago using half of an IDF. It looked crazy! Just bandsaw off the one half and leave the floatbowl intact!

[DWL_Puavo]

Half IDA picture from another thread here in cal-look.no/lounge.

[brian e]

That is awesome.  I will add it too my extensive list of someday projects. 

Biggest bummer is you would probably need to destroy a pair of perfectly good IDF's just to end up with a pair of single barrels slightly more tunable then kadron's.   

Brian

[Torben Alstrup]

Brian, what is your problem with the Kads ?

I´m not sure about the cam choice you listed. When I did that 1914 bus engine, I had a fk41 with 1,3 rockers in it at first. - good power, but not enough lower to midrange torque. I also tried the TSC 10 on 108 LC. - Still lacked lower end torque. So I sort of went back to basics and tried a W100 with 1,25 rockers on intake, which was the best of the 3 options, with 104 hp and 165 Nm torque. Very driveable and decent idle quality.

Even for a lighter car I agree that the 218/119 does not have enough split to equal the head flow, resulting in a soggy bottom end. I am working on a 2110 cc single port engine for busses (only on paper as of now) with this engine I am debating whether to use a CB 2239 (close to a W100) also with 1,25 rockers on intake, or use a FK42/41 cam with 1,3 rockers. The split cam set up seems to like a 37,5/33 mm valve configuration. I have a dummy head that flows 139 cfm @ 0,550" and 25" and 110 cfm on exhaust at 0,450. Deduct 16% from intake air flow, and you have the hp potential with the FK42/41 cam. The 2239 configuration pulls a little earlier and stops a litle earlier.

T

[brian e]

  I managed to get 123cfm @28" .450" with the manifolds and Kadrons bolted on. 
 

WOW! Nice numbers! Well done.

Interesting that the enlarged inlet dont really do much along with a stock intake valve. I get 120 CFM @ 0,500" and 25" with 31 mm port inlet and similar manifolds.
I did a set a couple of years ago with 37,5 intake valves and a D shaped port inlet, area wise i would say that it is most likely very close to a 34 mm Ø. With those heads I was able to get 135 CFM at 0,525" through welded and reshaped Kadron manifolds. Those heads reside on a 1955 type 1 which is Kadron fed. I have not yet persuaded the guy to come on the chassis dyno (Pity) But I´m positive that the engine pulls very close to 120 hp at 5grand. It is really strong for what it is.

I like messing with sgl ports too 

Torben,
  I was mistaken about the size of the intake at the head.  I tore the engine down last night due to a cracked case, and measured the intake opening at 31.5mm. 

Sorry for the confusion and my fading memory. 

Brian

[andrewlandon67]

Thanks all for the advice and encouragement! I have decided on a balanced 1904 singe port with mostly stock heads, h.d. valve springs, roughly 8.5 compression with straight cut cam gears, lightened flywheel, balanced stock rods, Kadrons, etc. The only thing I need still is a cam that will let the motor breathe properly. I've looked into some of Engle's split-duration turbo cams and was wondering what you all would recommend for a good cam/rocker combo for a decently quick daily driver bug.

[brian e]

I think I have come to the conclusion that unless the engine has a bunch of displacement, stick with right at 236° @ .050". 

Torben is right about my cam choice in my 1915cc.  With the 242° @ .050 it is a touch soggy, and its got a pretty lumpy idle.  In my bug it could have used a little more bottom end.  We will see what the guy who is getting it thinks.  If it doesn't pull soon enough for him, I think I will swap the 218/119 for a w100 w/ 1.25's on the intake.

I would like to try something like a 236°/228° and .460" on the intake, .400" on the exhaust, in a 1776 w/kads.