Kuhn Performance Technologies 32V 928S4 Twin Turbo Nearly Complete

Herr-Kuhn · 01-04-2007, 06:33 PM

Greetings,

I've come here as a new member to share some of my work to other 928 enthusiasts out there. My project was to take a garden variety 928 S4 and add the best form of forced induction, namely turbocharging. To further this, the system had to be top notch in its method of approach, both from a technical and aesthetic standpoint.

The 928S4 twin turbo system offers the following:

2 Garrett GT series liquid cooled ball bearing turbochargers 750+ HP capacity

2 Air to Air bar and plate front mount intercoolers 10"X4.5"X8"

High energy pulse flow designed exhuast manifolds, ceramic coated

Dual Bosch compressor bypass valves

Split exit downpipes, seperating wastegate exhaust flow from turbine discharge, ceramic coated

Dual air filtration and inlet snout system

Proprietary MAF junction box

JDS Porsche SUPER MAF

Shark Tuner massaged EPROMS, fuel and ignition as required

Run delay turbocharger water circulation system allowing water circulation through turbochargers after engine shut down.

This, that and the other...

This has been a very argued about project for the last 3 years. I promised to bring back a full blown (no pun intended) twin turbo system for the Porsche 928S4. Why? Beacuse the car is worth such a system and this is the way Porsche would have built it. I have been working with turbocharged Porsche 928s since 1990 and it has always been a dream to build the ultimate 5.0 liter 32V 928 street machine for me. I also grew really tired of hearing that a Centrifugal Supercharger was the "top dog" way to go for the 928 and that "turbos don't work on a 928" Some people claim this is an imaginary project, or won't work, won't outperform a supercharger, is too complex, etc. Not true as the below pictures show.

I investigated the "rear mount" turbocharger system for the 928 well over two years ago. I could never draw myself to even remotely warm up to that setup because the turbocharger is designed to extract the raw heat energy from the exhaust pulse. Additionally, mounting the air cleaner(s) under the vehicle was simply unacceptable to me. That meant front mounting was the only option for me, as it is for any factory setup or top notch tuner working in this field. Furthermore, splitting the bank loading with twins is the natural layout progression for a turbocharged V8 and is Porsche and Audi's choice for nearly all of their new turbcharged vehicles. In fact, BWM has seen fit to equip the new 3 series with twin turbos. The value is in generating an extremely responsive system, one which can deliver an ultra-wide powerband, not just a peak, chest-pounding dyno number. The widest powerband per pound of boost was the ultimate goal. I expect this setup to run circles around most new high performance cars on just 5 psig.

I attach some pictures of my project. In the next 3-4 weeks I will be putting the finishing touches on the system and running the car in. The first setup will run a low 8 psig, but I'm expecting some serious performance at even these low boost levels. After all we are chasing 5 full liters of displacement here with the latest in Garrett turbocharger design.

To date, this project represents 1000+ hours of investigation, engineering, fabrication, installation, etc. My motto has always been to do it the best way possible.

For those willing to write the check I can be willing to supply the systems. More information coming by February, 2007.

[img]
http://forums.pelicanparts.com/uploads9/IMG_2173+copy1167966275.jpg[/img]

Shane E · 01-04-2007, 07:32 PM

Looks real nice John. Even looks like most of it would work for an '86.5, just need a place for the throttle linkage.

Herr-Kuhn · 01-04-2007, 08:06 PM

Ah, the old 86.5! Actually if I'm correct the heads are somewhat different as well. I'll probably be going back and putting a similar manifold and modern turbocharger set like this setup on my 4.5 liter. The K-26/6 setup works really well on the 4.5 liter, but a set of these Garretts would really blow the lid off of things. The new wheel technology is leaps and bounds above the old school turbos...especially the turbine geometry with much smaller, higher flowing wheels. I really must finish this 5.0 build soon...the suspense is nearly killing me. I've been fabricating since August, 2006...and the investigation into this project steps back at least 18 months before that.

m21sniper · 01-04-2007, 08:49 PM

The exhause manifolds on S4s have more bolts than the 86.5 motors do IIRC. I seem to recall Dave Roberts telling me that once when i was discussing their X-pipe systems with him.

That turbo install looks awesome Herr-Kuhn, i want a freakin' ride when it's ready!

rhjames · rhjames's Garage

As I have said in my previous posts.....

Another product to consider. Much more to my liking on several points:

Air intake under hood--not under car.

Air intake in front of radiator--nice and cool, above the rocks and road kill.

Twin hairdryers--quicker spoolup (possibly) using smaller units.

Headers into turbos--every competition turbo-ed car out there uses some sort of tubular headers to feed the turbo's.

Herr-Kuhn is dead-on about heat content. 26 years of building/operating bad-ass diesel truck motors taught me that......(1000+HP V-8 Cat// 45 lbs of boost, 1250+ hp KTTA Cummins// 62 lbs of boost).

I would like to see the 16 V (K-Jet) set up, when you have a chance to offer......

One further thought:

"Compound turbocharging"

Think about it........better o-ring your heads guys!

Regards to all---rhjames

hacker-pschorr · 01-05-2007, 04:41 AM

Good work John.

I cannot wait to see the results.
Very cool intake, palcement of the air filters is perfect. I've seen other setups play around with that type of placement, very simple and effective.

Are the two intakes going through the fender?

Is there an IC down there somewhere?

Looks like you are in the home stretch.

Rixter · 01-05-2007, 06:33 AM

turbos suck, easier to put a twin screw on it and be done
hahahahaha.... jk
nice to see you're in the home stretch, I'm waiting on a call from your bro on the dyno numbers from his car

Murf928 · 01-05-2007, 08:15 AM

Wow John! Looking good!

Any chance you will have this car at SITM this year?

m21sniper · 01-05-2007, 08:40 AM

Hey Murf, how's it going bro? Long time no see.

sonett3 · 01-05-2007, 09:34 AM

murf928 this car will be at sitm this year

928GT and EuroS · 03:08 PM

Truly a work of art,
will be very interesting to see the results on the rolling road.
(and how the rest of the drive line can keep up with that

)

/Peter

MarkRobinson · 01-05-2007, 12:40 PM

Very cool John!

Rhjames: my 3.5" intake is not "under the car" just because the pipe is. It's a very roomy, cool, dry place that's at least 16-18" off the ground.

rhjames · rhjames's Garage

Mark,

I know what you're saying, I just prefer under hood for all engine components. I just couldn't "see" where it (your intake) ends up from the pics I was looking at (in front of the battery box/gas tank area.....? I hate these damn reader glasses...)

Not you're fault Porsche didn't make a cavernous engine compartment......

It's a good debate, these things we add on to each of our cars.

My roots are in drag racing, so it's difficult for me to even own anything that goes around a corner like my 928, much less think about how to (easily) double the HP output.

Still learning after all these years.......

Let's see, "compound" turbocharging, then intercooled, then nitrous oxide, then stroked and overbored.......wonder just how much these little engines will take....?

I did have a little fun with Corvette and a 7 series Beemer today......The Vette was giving the Beemer a good run, and then I sneaked (that's terrible English) up on 'em. What a surprise!

Keep after guys. When I get done building a new motor, I'll get serious about shopping for some more HP.

regards---rhjames