Kuhn Performance Technolgies 32V 928 Twin Turbo makes 500+ ft-lbs off the crankshaft!

Herr-Kuhn · 04-21-2007, 06:29 AM

I had my twin turbo on the dyno a few weeks ago. It was a bit of a let down as the fuel pump stopped me from doing a full pull as it ran out of fuel at 4,000 RPM due to a defective Bosch 044 pump. Regardless I did get some numbers on the car.

On 8 psig at the manifold the car put down 462 ft-lbs to the tire on a Mustang eddy current dyno. This torque came in at about 3,800 RPM. What this means is the twin turbo is supporting in excess of 500 ft-lbs off the crankshaft on just 8 psig on the manifold. I've reached the last load rung on the JDS super MAF map at about 3,800 RPM

I actually lost a wastegate line (not tight-my fault) and had the boost hitting at 12 psig to one bar for a short time out on the street. It was feeling a bit quicker that day

. No blown head gaskets, broken ring lands or the like. This is positive...maybe I should turn the boost up?

My goals moving from here forward are to tune in the top end of the curve to preserve the torque level for as long as I can.

My car is currently useless at putting down power until this Monday when the LSD goes in. I also have one slightly glazed clutch that took a beating when the screw was "turned up". It is okay because I have a Spec 3+ unit waiting to go in.

I plan to open up the exhaust on the car to a "proper" 3" dual system. This will effectively double my pipe cross sectional area compared to where I am today. The stock exhaust works well to a point, but by opening the back side of the turbines up I am expecting to pick up major horsepower on the top end of the curve.

The car is hyper-fast on the street. The turbos come on gangbusters. Right now it is difficult to even keep the car loaded up in 2nd gear because of the lack of traction due to the open differential. I can't wait to drive it after the LSD is installed so I can get the full traction I need.

Just a few little details to finish up...

Danglerb · 04-21-2007, 09:23 AM

I see drag radials in your future.

Herr-Kuhn · 04-21-2007, 09:55 AM

I'm thinking not on the drag radials...I would like my car to still be able to take a corner as required.

Danglerb · 04-21-2007, 03:18 PM

Pick the right tire and it does both, just not for all that many miles. Nitto 555 works for some. After you go as wide as you can, sticky is all thats left.

Herr-Kuhn · 04-23-2007, 06:35 PM

My limited slip has been installed. My clutch is completely gone at about 4,500 RPM. It won't hold the torque the engine is producing. I'm going to drop the package out early this week and get the flywheel cleaned up for re-install. After this I have to break the new clutch pack in for a few hundred miles. Nice excuse to drive the car for a week. I had to wait on the clutch disc, because Spec sent the stage IV unit which has no springs...it was rigid...I like firm shifting but that would have been too much. The Stage 3+ should do the trick for me pretty well. It is supposed to be good to 700+ ft-lbs but somehow this seems over the top for a single disc. If it holds around 550 ft-lbs I should be alright.

speedracing944 · speedracing944's Garage

do you have picks of where the turbos are located? What did you use for turbos?

Speedy

Herr-Kuhn · 04-26-2007, 06:09 PM

If you dig there are pictures on here from a while back. Mine are manifold mounted turbos to take advantage of the high heat energy out of the manifolds. The system uses Garrett GT series ball bearing turbos which are specialized to my design specs to fit the Porsche 928. There are two large front mounted bar and plate intercoolers which sit under each front fender as to not block any of the flow through the radiator (or AC system). All of the turbocharger hardware is good to well north of 700 HP. The system was designed to support 600-650 HP with some margin of safety. Of course to get these power levels, compression would have to be dropped to a suitable level.