single ports: what are their limits?

[nicolas]

maybe this is a stupid tread, but lets say i have a clean, very good set off singleport heads off a 1500 type3 engine and i want to use them anyway.
i read in the bill fisher handbook about the flow figures and exhaust is nearly the same, but inlet is a lot lower and never catches up with a stock dualport. BUT is it all worthless? or can this head perform well in a relatively small engine (1600 - 1800cc) with a modest cam that would put its emphasis on torque (powerband would be from off idle to 5000 rpm tops)? does flow say everything about them or is there something to be done with portspeed. bigger isn't always better has been said before, but can smaller go as well?
the type3 1500 engine in the S model in 64 was a singleport engine and made as much power as the 66 type3 dualport engine two years later.

you can discuss this as far and long as you want. 

just to give you guys an idea about a 'ballpark engine' i have thought up this:

69x88 engine with a w 100 cam or a vz series. type3 carbs (just to go dualcarb) modest CR off 8 - 8.5 or 1mm flycut in the heads. but anything goes.

[Jim Ratto]

maybe this is a stupid tread, but lets say i have a clean, very good set off singleport heads off a 1500 type3 engine and i want to use them anyway.
i read in the bill fisher handbook about the flow figures and exhaust is nearly the same, but inlet is a lot lower and never catches up with a stock dualport. BUT is it all worthless? or can this head perform well in a relatively small engine (1600 - 1800cc) with a modest cam that would put its emphasis on torque (powerband would be from off idle to 5000 rpm tops)? does flow say everything about them or is there something to be done with portspeed. bigger isn't always better has been said before, but can smaller go as well?
the type3 1500 engine in the S model in 64 was a singleport engine and made as much power as the 66 type3 dualport engine two years later.

you can discuss this as far and long as you want. 

just to give you guys an idea about a 'ballpark engine' i have thought up this:

69x88 engine with a w 100 cam or a vz series. type3 carbs (just to go dualcarb) modest CR off 8 - 8.5 or 1mm flycut in the heads. but anything goes.

Good post 
We are close to knowing what Sheep's 1800ccs/p will do.
Dyno Don has some fond memories of a hot rodded s/p that ran Engle 110 I think and kads (?)
I think the key is carburetion. I don't think the head design is going to have so much of an effect (yes some), but I think intake manifold and carburetion are the key, when it comes to increasing performance (esp thru increased overlap)
Think about single 2bbl or stock carb or two single bbl carbs on either dual port or single port: When not running one venturi per cylinder, you are apt to run into "reversion" even with moderate overlap, no matter if it is a single port or dual. The difference really is where the two intakes siamese... on a single port it is in the head, just after intake bolts to head, and in a dual port, it is at the end casting or the divergence in inlet manifold (i.e. dual Kadron, baby Dellorto FRD or Weber ICT). I'm not sure what effect "where" the divergence (separation) is has on how the engine runs and th resulting performance. The carburetor needs a clean strong signal to work best, right? If we crank in too much duration with shared barrels (like running single 2bbl Zenith on either single or dual port) the end result will be one cylinder per bank on intake stroke, one on exhaust, and with overlap (or even, with cam timing extreme enough, one cylinder on compression and one on blowdown!) you're going to end up with little vacuum in inlet manifold, and a 'confused' metering signal in carburetor. Yeah according to Bill Fisher and Kay Sissell's work in 1969 the single port even reworked couldn't match a stock d/p for cfm. But I don't remember if they talked about air speed. You might want to pick up AG Bell's book (Haynes publishing) called Four Stroke Performance Tuning and study the chapter on cylinder heads. Lots of info on how siamesed intake port heads work (like VW s/p, Mini 1275, and others). Formula Vee guys must have some tricks up their sleeves. Another book on my shelf by Philip Smith (Design and Tuning of Competition Engines, Bentley Publish) discusses some of the black magic behind Formula Vee porting... seems it is more about airspeed than CFM.
I have spent a lot of time wringing my hands and my head thinking about getting the ultimate in driveability AND power from Sheep's engine... I owe him in the tradition of me building him these weird engines that always ran hard....  I decided against that V26 (you got that right?) becuase of overlap, and landed on the cam I chose after researching similar cc engines that ran Bosch K, L or KE jetronic...  (CIS) and how much cam they could take before they were deemed undriveable. The design of the air flow meter (flap) prohibits the use of too much cam timing for same reason....
Hope this didn't bore the crap out of you.

[louisb]

Dyno Don has some fond memories of a hot rodded s/p that ran Engle 110 I think and kads (?)

I think it was a W130. This has been a pet subject for me for a while as well. I am really interested to see how sheep's motor turns out. How about a turbo SP motor? Bypass the intake restrictions all the way around.

--louis

[besserwisser]

Single ports are a lot of fun. Two years ago I did a quick and dirty 1600 singleport with stuff that was laying around in the shop. Not to much porting, quite a bit of flycutting, found a used 296 degree cam, some old retired racesprings (4046) and put the motor together in one afternoon. First version had a Holley bugspray,dynoed at 60hp. Changed the carb and the intake,put a 40DCN with separate runners and the thing really came alive. As the ports on single port heads are to small to do any porting you have to go for airspeed. I have also built a formula vee engine and it easily revs to 6500 on single springs without float. The secret is light parts. A few years back I tried to get some horsepower out of a 30horse. Put two 28pict carbs on it with dual springs and homemade pushrods. My guesstimate is that it made about 55-60hp but it wore out fast. I now have a stroked 30 horse in the making and with 1620cc I hope to reach 100hp before it gives upp. Single ports are fun,cheap and there are plenty around. I would like to build a big motor around 2liters with single port heads ,bigger intake valves and run a one throat IDA 48 on it. Would be interesting to see how much hp you can get out of single port heads.

[Jim Ratto]

Dyno Don has some fond memories of a hot rodded s/p that ran Engle 110 I think and kads (?)

I think it was a W130. This has been a pet subject for me for a while as well. I am really interested to see how sheep's motor turns out. How about a turbo SP motor? Bypass the intake restrictions all the way around.

--louis

Wow a 130 and siamesed intakes... that's hard to imagine running very well! Sarge has told me about his 1700 single port with single Zenith and Engle 125 and said it was a reversion monster, going into an asthma attack as the cam (finally) came in.

It would be interesting to build a close to square motor like 90 x 84 , and run a set of ported single port heads (focusing on air speed) a cam with about 260' @ .050" on intake and 268 on exhaust, and a single 48IDF Weber to feed it.

[louisb]

Dyno Don has some fond memories of a hot rodded s/p that ran Engle 110 I think and kads (?)

I think it was a W130. This has been a pet subject for me for a while as well. I am really interested to see how sheep's motor turns out. How about a turbo SP motor? Bypass the intake restrictions all the way around.

--louis

Wow a 130 and siamesed intakes... that's hard to imagine running very well! Sarge has told me about his 1700 single port with single Zenith and Engle 125 and said it was a reversion monster, going into an asthma attack as the cam (finally) came in.

It would be interesting to build a close to square motor like 90 x 84 , and run a set of ported single port heads (focusing on air speed) a cam with about 260' @ .050" on intake and 268 on exhaust, and a single 48IDF Weber to feed it.

It was a W120 not a W130. Here is his original post:

single ports heads rock !!.....and they do work much better on smaller engine applications as i had many a racer headhunting me down in the 70's at the vw bug ins as well as the vw drag days with larger engines than my 1600 and could not even come close to performance...my particular application was: 1600/non c/w crank/engle 120/1 3/8 exhaust with single muffler/s/p heads with sock valve size ported/polished with single h/d springs shimmed .060 on the intakes and .030 on the exhaust with a set of early kadron carbs..match raced several racers of notoriety and many with 48's and gave ALL a run for their money !!...first in my stock 67 with stock 4:37 that lived for years until a near fatal car accident in 77 then moved on and up with my first notchback and same combo with 148 third and 114 forth...drove the living crap out of this engine as my day driver getting over 40MPG and running almost 14's in the quarter mile(15:01 best) with street tires...could do easy 60ft burnouts and would often bet the big boys that no one could catch me first three gears....still have a signature set of s/p's in my garage with hopes to again tear up the streets/track...they work great when upgrading to 40x35 as well ...by the way when the engine came apart after 60k miles for inspection the case inside looked absolute bitchin'..no abnormal wear whatsoever..this is just a fine example of proper comdo and parts as well as proper maintenance......peace/dyno don

I am kicking the idea of doing a STF SP motor like this for a buggy with some of the left over parts from my current build.

--louis

[FDK/mrpedrini]

Verry interesting post!!
On saturdays i work in a little vw restoration shop, we do all the work from body work to engine rebuilt... There is one mechanic who is a formula Vee racer and builds his engine's himself. One day he brought his formula Vee race car for some maintainance... And so he'd started the engine and to my disbelieve it revved till 7000 rpm!!!!! The engine had a displacement of 1300cc and was running on a stock (single!!!!) solex carb (don't remember wich PICT it was) and was running single port heads..... I was verry interested in what the magic behind this engine was and he told me there was a lot done with the weight of the moving parts in the engine..... And also some drilling and plugging to the stock carb... But he also said that an engine like this won't last longer than one race season....

greets Dennis....

[Tony M]

Back a few years ago built a bus engine for a old man in Washington - s/p 2180cc - Yes thats right - all the guy wanted was a big torque engine - stock cam, heads, carb. It ran very good - tons of torque - just getting the jetting right was the biggest deal - once that was done it would pull a stump out - then he was towing some place and had it in 1st gear and blew the hell out of it.

[Zach Gomulka]

The only way I'd run a one holer is if I bought a running car with it, and even then I'd slap on a pair of Kadrons (I have a pair of manifolds and carbs just in case ). I'd never build one, just don't see the point!

[volksnut]

A few years back I had a 88x69 motor (machine in 88's) with a set of ported single ports (37x35.5 SS valves) HD single springs, Scat C35 cam, 1.25 Autocraft rockers,lightened flywheel, 8.0 compression, 1 3/8" single muffler extractor and a pair of Kadrons....ran 10.30's in 1/8 mile, never really tuned it, but I'm sure it would have run high 9's..... man what a combo, loved it

[lawrence]

Single ports are cool! Torquey little lumps. When I bought my car I received a running 1641 as part of the deal. It was based around a 1300 and was stock except for the 009 distributor, extractor header/ j tubes, single quiet pack and slim gauze air cleaner. If I had a scanner I would post pictures. It ran 19 second ETs at both sears point and sacramento raceway.

Hey, you guys with the hi-po single ports should post your specs in the Cal Look Engine Combos and HP thread.

[fish]

Very interesting thread, have always wanted to build a little SP beast.

[Jim Ratto]

when I was @ BH, if a customer came in with a single port, or wanted a really good running engine in a 1970 or earlier car... we ALWAYS suggested a single port. Common engine we built was 87 x 69 or 88 x 69 with single ports. I wasn't convinced until I drove one. The boss let me borrow his white '68 one night, and I couldn't get out of the car because it ran so well. Increase the cc, keep single port and you won't believe how well they run. If I was running a stock carb I would choose a single port head every time.

[nicolas]

thanks allready for all opinions. some cool ideas allready.

not sure about a single 48IDA... but it could be done. there have been manifolds made, but i read (again bill fisher book, yeah i have been rehooked to that one for a few weeks now... ) that it runs bad and only gets 8 MPG.

what carburation would work? kadrons could be the dualsetup as would be type3 carbs ( a bit like a Ritter setup) or would a single carb be better (holley bugspray  )

and you mentioned bigger valves, but i am not sure if i go that for, and if it is better as the inlet (manifoldside is not too big) but maybe bigger valves have other advantages that make it worth the effort/pesos

[speedwell]

what carburation would work??

stromberg  cd 150 ........................ ..

[Donny B.]

One thing that is neat about single port heads is that you can get the CB head mod that allows all the cylinder studs to be the same length.  I think Porsche did something like this.  I always wanted another strong 1600 single port for a back up.  My original one built back in the 80s would rev to 6000 with an Engle 100 cam and a 30 Pict-1.  Floated the hell out of those valves with stock springs and broke my share of pushrods, but it was a lot of fun to drive.  I had 1 3/8 fortuned extracter with dual quiet packs.  It was really quiet.  I still have that exhaust somewhere.

If I were to do that today I would talk with Joel Mohr about his single Kadron setup.

[Jim Ratto]

thanks allready for all opinions. some cool ideas allready.

not sure about a single 48IDA... but it could be done. there have been manifolds made, but i read (again bill fisher book, yeah i have been rehooked to that one for a few weeks now... ) that it runs bad and only gets 8 MPG.

what carburation would work? kadrons could be the dualsetup as would be type3 carbs ( a bit like a Ritter setup) or would a single carb be better (holley bugspray  )

and you mentioned bigger valves, but i am not sure if i go that for, and if it is better as the inlet (manifoldside is not too big) but maybe bigger valves have other advantages that make it worth the effort/pesos

If I were going to use a large bore carb, i.e., 45mm+ I would want to make sure the engine had some cc in it, to ensure that the carb is going to get some "pull" through it. I'd probably stay with the DRLA or IDF since they have a more refined metering system in the progression range (I think the big daddy IDA works on IR systems... I bet the carb insists each throat feed one cylinder). I bet the carb tuning is going to rely more on correct selection of emulsion tube too... over that of 1bbl per cylinder.
How about a fabbed manifold supporting a 45 or 48mm downdraft Weber or Dell, or if there is room, a DCOE Weber. Have the manifold taper from throttle bore size gently down to 35-36mm ID (increase air speed), and how about some anti reversion bells in manifolds, to quell intake reversion back to carbs (looks like inside of glass pack muffler).
If I could get Sheep to agree, I'd have a tubular manifold fabbed up by Johnny Holleran to feed his engine with a 2bbl Weber. But he is insisting we run the stock carburetor, which is fine. I just think had we isolated the throats among at least 2 cyl each we could have stepped up in valve timing (I ran 256' @ .050" with single 36mm Dell'orto on 1641 years ago, yes it was cammy, but completely drivable).

[louisb]

I have a bugspray so I was thinking of using that for kicks and grins. Found a Manx body for $500 last night at the local club meet. But I dont think I want to jump into that one right at the moment.

--louis

[besserwisser]

When I said single 48 ida I meant dual carbs but you only use one throat on each (old formula vee trick) Looks sick but revs like no tomorrow. You just plugg one throat and use a homemade single port manifold. A 48 ida mounted in the middle would be very hard to get some jetting to work well.

[stealth67vw]

Not mine, but how bout a 2110 turbo single port with 40 x 40 valves? As a 1600 turbo S.P. it ran 13.1 @ 97 coasting from the 1000ft. mark.

[fish]

That engine looks absolutely sick. I may have to rethink the engine combo for these babies.

T25 with 2" SU should be nice with Hemi SP heads.........but what Cam? FK65 maybe.