Vonov

Thanks...forced induction is indeed the plan (I traded my friend Doug a Suburban he needed for a shop vehicle; he's supplying the turbo hardware)
As for the narrowness of the motor, the Fiero crowd over on Pennock's is getting excited about this motor, and one of the reasons is that maintenance is pretty easy compared to almost any other engine in that car...it's the only V-motor that lets you change the plugs as easily as an inline four or six; not a small consideration when you're dealing with a mid-engine car. (Used to own a Fiero with a 4.9 Cadillac V-8; it was quick enough, but my VR6 Jetta would actually beat it on top end.)

Vonov

If by crossflow you mean intake all comes in one side of the head and exhaust out the other, yes, it is...the two camshafts are rather stunningly ingenious (especially the way they did the 24 valve head)... in the 12V, each cam operates half the intake and half the exhaust valves on each side of the head; in effect, it's a SOHC V6, with both cylinder banks sharing a single head, and both cams in the same head. D'ye begin to see why I REALLY like this motor, and why I thought it would be a good candidate for a swap for this car? It's a really beautiful piece of German engineering.
Here's a tech article that explains it better than I do:
http://www.autozine.org/technical_sc..._packaging.htm
I chose the 12V because it has more grunt at the bottom end, and FI will take care of the top end, although my Jetta pulls strong all the way through seven grand, at least in 1st thru 3rd (I haven't tried it ALL the way through fourth yet; I'd rather not lose my license, and third is pushing it in that department; haven't had a track day I can attend yet, lol).

FRporscheman

12v is the way. 24v would make a good track car or dyno queen but we like to tear up the asphalt right?

I too am amused by the head design and camshaft setup. They can boast "DOHC" because it technically is, but it's still 2v per cylinder. For a kick, read an article on the 12v head, then the 24v head and compare them.

The vr6 head is very inefficient because of the 3 ports going through to the far side of the head, but like any engineering problem, it can be solved with precision or brute force(d induction).

944Ross

It would seem like the long exhaust passages for the "far" cylinders would cause heat rejection problems, or gasketing problems.

flosho

I like!

Vonov

Not that I've ever heard of...I think it has to do with the engine's asymmetric layout...the exhaust passages run together, as do the intake (except the end cylinders)...I've also noticed what looks like some sort of equalization port between the short and long exhaust ports, which may help the engine breathe, and also helps cool the exhaust gases more rapidly by allowing a greater pressure drop than would normally be possible without causing a loss in back pressure, but that's merely a guess.

jonnybgood

The cutaway in the article shows cavities around the long exhaust port. I would assume those would be cooling passages to take away some of the heat.

good luck on this project. I think it is exactly the right engine for the 944. One could dream that Porsche would use the VR6 for an updated 944. Yeah, I know, dream on...

blown 944

so what are the true hp/tq figures being generated regularly with these engines?? At a moderate boost level say 20 psi??

Any flow numbers on the heads or cam specs (stock or aftermarket). My interest is piqued

I just watched a few youtubes and the sound of these engines is very nice. This is one of the things holding me back on an LS1, I just can't go along with that sound in a 951.

333pg333

This is a good thread and fun to read although I don't buy into the 4v per cylinder meaning you loose a lot of tq. I think it can open things up top but doesn't mean you have to loose your bottom end, no?

blown 944

Really depends on how quick of a turbo you use. Generally though the larger runners and valve area drops tq in the lower rpms unless you are running a variable valve timing setup.

Basically what happens is that you can't pack enough air into the larger runners to keep the velocity up in the lower rpms, hence the drop in TQ b/c the engine is not in a good VE situation. With a super quick spool turbo though, these issues would be resolved

V2Rocket

super quick spool = 5:1 pulley ratio centrifugal

Vonov

I've heard from several sources that the 12V motors definitely have more grunt on the bottom end than the 24V motors, although I haven't talked to anyone who has the later 24V motor with the VVT intake setup. Input, anyone?
(Be glad when I get these blasted stitches out; sort of champing at the bit here.)

Vonov

From what I've been able to find on the 'net, I'm seeing HP numbers from numerous sources, ranging between 280 for a mildly boosted engine @ 8#, to 500 hp @20#, on stock crank, pistons, and rods. I'll be happy with 300hp, because I don't like breaking stuff, lol...but Doug is telling me I should be prepared for 400...I need to see what he's cookin' up, lol...and he's sorta naggin' at me to get on the stick with this thing, but my court schedule hasn't been cooperative lately, lol...I'm thinking he wants to have it ready in time for next year's Southern Worthersee event...by the way, anyone unfamiliar with it should check out the town of Helen, GA...the whole town features German cuisine, architecture, and of course, BEER!!!

EDIT: Stitches come out TODAY!!! Woohoo!!

WRC_413X

Dont forget if you end up running into overall height clearance issues you can do a short runner intake, which would be better anyway for turbo, and you'll have the space.

when i got my 944 and started buying engine parts $$$ and reading up on how the engine is pretty much a timing time bomb i definitely thought about doing this swap being a big MKIII VW guy. Now thanks to you its definitive

Cant wait for progress!

FRporscheman

Even if the intake is changed, the valve cover still sticks up as high as the intake unfortunately.

I too don't think the burble sound of a chevy v8 works in a 944 or 968 body. But I suppose this is because I'm so used to hearing a whimpy whine, so that may change.