hot VW motors with "sports car" personality

[Jim Ratto]

Hi guys,

I'm enjoying all the latest talk about the mega-rpm, tightly-wound mini-motors....I've always been an advocate of twisting a small cc motor within inches of its life to get the last ounce out of it...hope somebody gets on it soon! (that means YOU monkiboy! )

Now at another spot on the hot VW motor spectrum....how about hot engines with more of a "sports car" characteristic, not so much of a race or a drag car personality? Maybe it is hard for me to describe what I am talking about. I'm not getting at making a "Bus" or "Baja" torque, truck motor. But a motor that can travel in any climate on pump gas, and has decent response off idle, will pull rather well from 2500rpm and up and then really come on strong at 4000 and run up to 6500-6800, without killing itself. Fast enough to be fun. An engine that makes merging onto the freeway a real joy, and traveling over a curvy, two lane mountain road even more so. Sound of the motor (as in any proper sporting car) is all important. I think coming up with a useable 170hp or so is about what I am thinking.
Think about other vintage sports cars with a more-than-adequate amount of horsepower....I always come back to the early 911S or Alfa GTA (twin plug)
both in the neighborhood of 160-170hp, depending on state of tune....what a joy cars like these must have been. I've been lucky enough to drive a 2.4 MFI 911 and it was surreal...the way it howled and screamed up to 7000rpm.
Anyway, where am I going with all this? I just thought a discussion on setting up a VW motor in this form might be a good topic. Earlier this year, I set my 2165cc up to reflect this way of thinking, and while I still think it could use more cam, I am really happy with the way it just "drives."

Now about a wilder cam...I have this 86C sitting on the shelf....just need to come up with a "reason" for my wife, so she'll be cool with me pulling motor down....

[louisb]

Sounds like you want a T4 in a German Look car. 

I think the first thing I would do is ditch the carbs for FI. Or at least the IDAs for IDFs. I am about to run out the door, will think on it some while I am out.

--louis

[louisb]

When I think of sports cars I think of high reving smaller motors. (Okay European sports cars, not talking Cobras or Vets here.)

Light weight valve train, say carbon fiber pushrods, ti valves, roller rockers, lightweight lifters. We can go with the 86c but run it retarded to get the rpms up. (Say 4000-9000). Lets make it a roller while we are at it. 

Crank would be 78 at most, 90.5 or 94 bore. Ti rods 5.5 length, Forged crank with all the goodies.

Heads will make or break the deal. Smallish valves to allow the springs to live at high rpms. (4 valves would work better.  )

48 IDAs with 40 or 42 vents on short intakes.

Tranny would be a five speed with road racing style gearing. 

Put it all in a Ghia for better high speed handling and lower center of gravity.

--louis

[nicolas]

louis is quite right, no need for IDA's in that one. IDF's would run great. i think i have seen that car here in Belgium... kinda.

it is more in the style my engineshop builds cars. IRS suspension, wider tracks, drysump, and a cam that is less peaky. he has a lot of experience is 6 hour and 24 hour races and therefore builds engines and cars differently. not sure what he runs, but it is a type1 setup with a 84 crank, 94 PC, eliminator heads??? and a set of IDF's as they are more tuneable (not me saying this, so don't fuss  )

the thing i think is quite key in this is build a big engine like we do, but not squizing every usable pony out of it. say you build a 200 hp engine and only get 170 from it, so it is easier on the parts... i hope this makes any sense.
and by using the later 1303 models they have the benefit of the front suspension.

if you want i can ask him more about it... but i think there are other points of vieuw on the subject

[louisb]

I am not really sure I see what you want other than what you have now. Somehting like a 2007 w/ FK8 & small heads? 48s w/ 37 vents. Back it up with a five speed. Sounds like you want something like the blueprinting motor w/ a bigger cam.

Sorry,

--louis

[louisb]

Now how about an "excuse" to swap cams??? 

When have you ever needed an excuse to pull that engine apart.  I think I would try larger vents before swaping the cam out. The same combo you have made 200+ hp in the motor build off with 42 vents. (One built by James2 though it was Dells.) Bigger vents should move the power bound up a little and give you some more top end as opposed to the 37s. If you really want to put the 86c in, call it a comparison for scientific research.

--louis

[javabug]

...a motor that can travel in any climate on pump gas, and has decent response off idle, will pull rather well from 2500rpm and up and then really come on strong at 4000 and run up to 6500-6800, without killing itself. Fast enough to be fun.

Hey Jim, I think I feel what you are getting at.  BUT...how much different would this be than the popular 82-stroke motor combos that are running around these days?  That is more or less the feeling I am shooting for with my 2110 build.  Or am I off base?

[louisb]

If you decide you want to try the 42s and dont have a set I will trade you mine for a set of 40s. 

--louis

[Donny B.]

I think louis hit the nail on the head.  What you described is my engine except for the HP.  Mine only makes 140 at the crank, but it pulls from 2000 on up and comes on strong at 4000.  It will pull all the way to 7000 in the lower gears.  I have the 5 speed and DCNFs a very driveable combination.  I am running a K8 with Berg 865 heads.  The ports aren't real large but they work very well with my combination.

[sheep]

I think Jim should just get back to work on my motor and quit daydreaming about other motors.

[louisb]

I think what Jim needs is an early 911. 

--louis

[louisb]

I think I see what you are getting at. An engine that can produce the types of power we do across the rpm range without having to rebuild the dang thing every 20,000 miles. I really think the limiting factor though is not just the engine but also the trans and weight of the car. (How much does a 911s weigh? and it had two more cylinders.) I think the engine I mentioned, in a very light weight bug, or VW based kit car with a five speed would be the answer.  Otherwise you have to get into some exotic stuff to prop up the engine's short comings and size limitations.

--louis

[sheep]

...a motor that can travel in any climate on pump gas, and has decent response off idle, will pull rather well from 2500rpm and up and then really come on strong at 4000 and run up to 6500-6800, without killing itself. Fast enough to be fun.

Hey Jim, I think I feel what you are getting at.  BUT...how much different would this be than the popular 82-stroke motor combos that are running around these days?  That is more or less the feeling I am shooting for with my 2110 build.  Or am I off base?

I guess the way I see it, the differences would be:

1. valve lift: I don't think many (any?) factory-tuned sports cars run much over .490" at valve (12.5mm). Hanging the valve way out there means the heads need to be checked for guide wear and springs die sooner. Right? Are our hot rod VW's part of an elite group that can only go "fast" if we run .600" lift?

2. Duration is a concern, but under 270' @ .050" should be "sporty" and driveable, I think. Some of the hotter European Giulia cams were about 300' off the seat, and the 911S was 320'!!!!  

3. Carb setup. I've tried 42mm vents, my car was not happy. Asked for downshifts if under 2800rpm, especially on incline. 40mm's and 37mm's are 100% better, at least by engine response on my usual "test track." I have a math formula that is supposed to guide you in the direction of vent diameter...whoopee...driving the car is the proof to me.

4. Heads: Admittedly, I haven't driven a hot VW motor with CNC Wedgeport heads but I know they're potentially fast. Do these heads run good all the way up? Or are they 5K and up? I think factory sports cars typically run "small" ports (the Alfa GTA actually ran smaller ports than the pedestrian Giulia!!)

I don't know maybe I am just wasting post space.....



[/quote

I agree with the very last thing you said

[nicolas]

i was telling you this because of the fact that it is a car that will pull from low RPMs to high, fast and still be driveable. in fact there is a car that was build much in that spirit by a guy that came there all the time. the only drawback is the drysump sitting inside the car. or you can see that as a plus in heating...

ps i don't think this is a waste of space as i think that such an engine must be great pleasure and maybe with my car (heavy type3) a better choice as a dragracing engine... so please post some more ideas.

and for the rebuild: just tell your wife the heads fell off when she walks into the garage... or better yet, that sheep took the engine apart to see what oil was in it  (sorry sheep, but i actually think this might be a good excuse as Jim is dissing you all the time)