Apexx

We never had pull that put down that kind of number 936whp was the highest and that was in its drag racing form
The lap record was at the local PCA autocross track called the Mineral Ring

tommo951

Come on please explain. We have been talking recently about the standard bore of the exhaust being a huge restriction. From the picture displayed the exhaust bore is def not 3" more like 2.5". We have been discussing how to make real power you need a "trombone type arrangement where you start tapering the exhaust out to a bell. This car apparently puts down 600hp. If the exhaust had been such of a restriction surely with the budget available it would have been simple to go to 4". But they didn't. This is my question why?
Admitedly I am more familiar with N/A cars, hence why I am asking questions rather than making statements. Somebody please explain this one

Porschefile

I really don't get why it's so hard for people to understand. I mean, there is no need whatsoever to over-think this and try to get "scientific" about it as others have in the past. The fact of the matter is you are trying to force a large volume (especially a car like this one) of airflow out of the motor. The one important thing is the diameter of the pipe you are trying to force it through. A volume of air being FORCED through a smaller pipe is going to result in increased effort, pressure, backpressure, or whatever else you want to call it. It doesn't matter what kind of scientific evidence or proof I or someone else is able to come up with to "support" what I'm talking about. The fact of the matter is a 2.5" pipe is WAY too small for an engine that's generating 600 horsepower worth of airflow. Especially if that car is being revved out high in the rpm, eliminating backpressure is even more vital. That car should run nothing less than a straight 3". I'm sure some sort of tapered 3.5" or 4" exhaust would have somewhat of a worthwhile benefit over a straight 3" as well, though how much so is anyone's guess. Don't ask me to get scientific because honestly, I probably couldn't come up with any "formulas" or math that's going to prove my point. I'm not the "technical" type, I just know what works from personal experience. Running a 2.5" exhaust on a 600hp car is just plain stupid, and there are no 2 ways about it. Unfortunately it seems there are very rarely any true back to back comparisons in our community, and it seems like because of that lots of people here are skeptical about a lot of these things. If people took a look outside this community they'd realize how ridiculous it sounds to run a 2.5" on a 600hp car. Hell, don't take my word for it, ask someone like ST that has a high horsepower 951. I remember distinctly he even reported quicker spool on his turbo when going to a larger IC/piping despite people trying to scientifically explain how it would be laggier.

Honestly, I wouldn't look at cars like this and automatically assume that everything was done perfectly and that whatever was done to a car like this is always necessarily the right way to go about building a similar car. No offense to anyone here that may be associated with Norwood or may have worked there but, whoever came up with a 2.5" exhaust for that car (if it truly is ~2.5") is an idiot. That's a pretty unacceptable power compromise considering that car was built specifically for racing. I mean hell, even the Turbo Cup exhausts were larger than that. The one compliment I will give is the intake design on that car is very nice and pretty much exactly how I'd build one if were not so incredibly lazy.

3" > 2.5"

Fastest928

My wife and I were in the shop that day and that # was on the dyno sheets I saw....what was it from?

I ended up buying alot of "old" experimental head parts from Bob...lifters, valves, heads, stuff that did not work (always worth knowing what does not work). One port config flowed over 400 cfm at a mere .500 lift at 28"...and it was "bad",,,

It sounds like you worked there for Bob, what was your role?

Porschefile

Damn! Sounds like someone went to town boring the ports out. I bet it now has the airflow velocity of a gerbil fart!

Apexx

I don't know because the Stage 4 Testarossa twin turbo cars only put down 1036whp and that is a 5.0L F12 running 28psi boost
1100whp is a big number

Yeah worked with Bob for almost five years
I really did not have a specific role there were only four of us that worked on the shop project cars on a regular basis. We sat down and created a long to do list as you finished a task you would just move on to the next one

Chris White

Before you guys go on a 4 page long diatribe about exhaust size – its not uncommon for a track car to also have a muffled set up for moving it around the shop / street.

evil 944t

Not really, considering a stock 968 head get somewhat close @ 550. Some portwork and a valve can flow way more than that(not that you need it).

eman930

How have I owned and been involved with the 944/951 family for like 10+ years and this is the first time I've heard of these "Doom" cars, I'm totally in love with the mystery behind it all, It's to bad there isn't more info or pics... I love secret mysteries of the 944/951 models

Chris White

Yep, don't underestimate the 16v head for top end power. With stock sized valves, stock cams and a minor port clean up (just smoothing a couple of rough areas) it will make 600hp at 1bar (with the right turbo and engine management of course!).

Chris White

To call the Doom car(s) 944s is a bit of a stretch. In reality the first Doom car was a heavily modified 914 chassis (not much 914 left in it!) with inboard suspension loosely based on an Indy car design, midengine design with a 968 based motor.

It did kick everybody’s butt and PCA reacted by making it illegal by enacting some rule changes. As much as a liked the idea I can’t blame PCA on this one – who would want to go racing against a car with the build and budget that this one had – the engine was so stressed that it had to be rebuilt after every race. I would guess that the race weekend budget (including trackside support) was in the $15k - $20k range.

Later Doom cars turned to drag racing….!!?!

evil 944t

I agree it will make HP with stock cams but, why use stock cams??

Chris White

"baseline".....start with the stock cams and work up from there!

evil 944t

No problem, agree to disagree. I would just go with a known turbo grind.

Chris White

I like a lot of data, so starting with stock cams and making changes gives me the info on how much improvement is being gained with each change. It takes more time but in the end you know how much you get for each change.

Cam swaps are not much fun on an 8v but with the 16v you can swap out cams while the engine is still on the dyno (the twin cam drive helps too – cam change in under 10 minutes)