rage2

Here's a thought...

The stock exhaust/intake/turbo plumbing for the 944 turbo is horrible. Who designed this? Exhaust comes out of passenger side, routes to the driver side of the car into the turbo before exiting back to the passenger side. The intake charge goes from the right side of the car into the turbo (which sits under the intake manifold), comes back up into the intercooler, to the other side of the car, then BACK to the driver side again into the intake manifold. Talk about a recipe for lag!

So, downsides to stock layout :

- Large drop in exhaust energy before reaching turbo. Lag!
- Heat soak in intake manifold with glowing hot turbo sitting underneath it. Heat rises right?
- huge path for compressed air to travel after the turbo. Lag!

A few years ago, there was a 944 turbo racecar locally that had redesigned plumbing. The guy built a log style exhaust manifold, which feeds the turbo on the passenger side (a hole had to be cut in the firewall for turbo) and of course exits back underneath the car on the same side. Intake plumbing went from the air filter on the drivers side (nice and cold), left into the compressor in the passenger side. Exits compressor into intercooler on the passenger side. Exits intercooler drivers side straight into the intake manifold... so the intercooler flow is backwards from stock. This eliminates all 3 problems of the stock system and spools up turbo much quicker. Also, wasn't restricted to KKK hotside turbos, and saved about 50lbs of plumbing.

So the question is, is there enough room to build an exhaust manifold that allows turbo placement on the passenger side without cutting a hole in the firewall? Anyone attempt this or heard of other success stories? SFR, think it's possible? .

evil 944t

Rage, I have seen the set up your talking about. After seeing it in person, I don't think there is enough room. The intake was actually in the passenger footwell, through firewall. It was on woody weiss's race car. huge front mount IC and 580hp 2.5ltr drysump awsome car!

rage2

Did he use a log style manifold? I think if we can put in a more elegant manifold, there might be enough room...

Log style manifolds will REQUIRE the hole in the firewall for clearance, because they're just so space inefficient for our setup.

mochman

actually I think a log style manifold doesn't scavenge the cylinders as well, with a maf and different ic pipes that problem isn't too bad, coat the header and crossover pipe wrap the turbo for heat. Anyways when the car is moving the engine heat isn't too bad. What I'm trying to say is there's probably a better way to spend money.

evil 944t

its a header style manifold. It moves the turbo almost in the middle of the firewall.

Russ Murphy

>>>What I'm trying to say is there's probably a better way to spend money.<<<


You mean like $15K for a lifter accessible cam tower and Milledge cam and head? If you've got standalone and efficient/big turbo then how else do you advance your motor performance?

David Floyd

How about turbo in the engine bay passenger front, like the Norwood car in Excellence a few months ago ?

TonyG

Russ Murphy

In case you understood... the cam tower thingy was $5k - $10k for a batch of 5 units, and was just an estimate, thus the cost per isn't more than $1k - $2k...

TonyG

Russ Murphy

TonyG,
I absolutely misunderstood. Thanks for the clarification. Even if it were more expensive $1K-$2K, I still would consider it a great idea. My point was that our options are limited after 370-ish rwhp.

Matt Sheppard

The reason Porsche moved the turbo so far away from the exhaust side is to prolong turbocharger lifespan IIRC. Wouldn't encapsulating the heat in the exhaust system be a more "elegant" route. I've often thought that if you have simplified the vacuum lines under the manifold, why not bend up another heat shield between the manifold and turbine. you could heat-coat the turbo exducer housing and the underside of the manifold.

As David Floyd mentioned, the Norwood plumbing route seems to be the shortest of any solution I have ever seen. I mean the turbo is right there before the intercooler and has real short, equal length tubular primarys. It seems one can even rig headlights to function in stock format if you relocated the coil and nixed the washer-fluid res. and used that space. This wheel has already been invented!

What is a "log-type" manifold? Do you have any pics.

AlexE

The old callaway turbo kit that I had, had the log style setup. Definitely some benefits to the setup.

The turbo was an IHI rb6 and was small enough to sit on the exhaust side.
If you want to go larger you will need to cut the firewall.

I think there may be better ways to spend the money if that is what you are after.

Matt H

Tony, I misunderstood you too. I thought you were saying 5-10K per piece.
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rage2

Depends on who you know. I have a friend who's a really good welder and have built tons of custom one off honda turbo manifolds. It can be done cheaply .

Plumbing isnt' that expensive if you can find the right guy hehe. I'll bet I can accomplish it for under $1000usd. Just curious if it's been done before, or why it was never done. Performance benefits? I really don't know because I've never driven a 951 with such a setup, but I've driven 2L cars with way bigger turbos that spool up faster than my 2.5L 951 (identical compression ratio). I'll bet there's some gains there.

I didn't know the Norwood car had the front turbo mount. Anyone have pics of the article?

Olli Snellman

Check out turbo location on this 951:

http://www.lindseyracing.com/cust1a.htm

AlexE

The old callaway had great spool up characteristics.... I think you will have great gains if you go with a larger turbo with the shorter plumbing. I would think callaway was the first to create an exhaust side turbo conversion even though it was on an NA (with stronger internals..etc) It really is a tight fit on the exhaust side. I wouldn't consider it a novel idea but definitely one that could prove to have some great end result posibilities. I guess it comes down to cost to benefit ratio of such an endeavour...

OZ951. That car in that link is sick.... in a good way.