Kuhn Performance Technologies 32V 928S4 Twin Turbo Nearly Complete
 

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.

SmileWavy

http://forums.pelicanparts.com/uploa...1167965896.jpg

http://forums.pelicanparts.com/uploa...1167966019.jpg

http://forums.pelicanparts.com/uploa...1167966149.jpg

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

http://forums.pelicanparts.com/uploa...1167966414.jpg

http://forums.pelicanparts.com/uploa...1167966558.jpg

http://forums.pelicanparts.com/uploa...1167966687.jpg

http://forums.pelicanparts.com/uploa...1167966816.jpg

http://forums.pelicanparts.com/uploa...1167966953.jpg

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

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.

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! :)

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







http://forums.pelicanparts.com/uploa...1167981005.jpg

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.

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

Wow John! Looking good!

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

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

murf928 this car will be at sitm this year

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 thatSmileWavy )

/Peter

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. :)

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

New dyno run coming for triple t

Yes it looks very nice. Dang Shane, thanks for sharing :P

Yikes, can't wait to see this at SITM!

Thanks for the feedback guys. I've been out of town on business this week in Chicago and had an issue with the laptop.

Also Herr Kuhn... Das ist ja wirklich unglaublich!!!

Nice one, John!

Just a few more weeks and she will be on the road!

When will the price and availabilty be announced so I can figure out how big of a bank I need to rob?
Seriously though, will this system be for sale?
By the way, great job, there is no substitute for doing something up right!

I am still working out all of the details on the cost of the components. The plan is to offer the system for sale. I never set out to produce a lot of systems, but to try and produce the best forced induction system for the 928. Turbocharging is a natural for a car of this type for many reasons including the following:

No added stress on the engine when just cruising (no belt tugging the crank)

You can be cruising at 15" Hg and boot it hard and have full boost pressure in very short order.

Very low noise levels

Most efficient way to add power to any engine

No belt to slip or break

Smooth roll-on of power, but only when you ask for it

Boost as a function of load, not RPM.

Overhead capacity to go really far if you want to turn up the boost screw

Superior modulation of boost to the manifold, use it only when you need it. The turbo allows you to run in a little boost or a lot, based on load and throttle position.

Where it counts it is hard to beat a turbocharger, namlely across the mod range and top end. The 928 is not a 0-60 car, but rather a touring car that loves to eat up lots of road when you drop the hammer. I already own a 1981 Twin Turbo 4.5 liter that performs really well out on the open road. I'm expecting a lot more out of this car...500 ccs more plus a much higher flowing head and intake should make for some great results. 600HP out of this engine should not be too difficult at all. Who knows, I may even be surprised with it.

As I stated I am still ironing out details on the costs so I can set a sell price. This system will not be competing on price with 928 SC systems, but on the flip side, the price will be reasonable for what is included. There are a lot of parts, none of them all that complicated, but there are a lot of them.

I need to finish this build, run it in and then do some serious daily driver testing of the car. Once all of that is completed, I will be able to come up with a final number and then do a proper product roll-out. I would expect things could be ready to up and going by mid 2007.

Thanks for the positive feedback.

extreme ditto there
also when is a 16v coming?
herr kuhn , i know it's not what you would consider an ideal application. but still ...

I've built three TT 16V cars already. I could reproduce this into a 16V setup...but right now the goal is the 32V system. A 16V TT 928 is still a really potent car. I've managed 375 WHP and 415 ft-lbs out of the 4.5 liter.

Reproducing the 16V would depend on interest levels and how much people were willing to spend on the system.

The air filter pieces are especially neat. Bet there would be a demand for a few sets if you could replicate them.

Agreed.

Herr you could make a very pretty penny marketing those airboxes and tubular metal intake runners. I'd definitely buy one if it was 200 or less. :)

herr kuhn. i don't know , but i imagine you're just as busy as i am.
however, do you have any idea about what figures on funds would look like for the 16v set-up?

It would be pre-mature for me to speculate on any pricing for 16V right now. If I want back in to do the 16V stuff again I would use manifolding nearly identical to this...my jig bolts to the bottom of the heads and then you connect the dots.

I am thinking about going into my 81 4.5 and using these GT series turbos on that car along with a new set of manifolds like these. That means I'll have a K-26 manifold/turbo/wastegate system that will not have a home. If I go this far I might be willing to sell the K-26 system...but that that is a ways off for me. I need to see what these 32V results will be before I make any changes on the other car.

On the snouts...I have made molds for these parts, so reproduction is very easy for me. It is somewhat time consuming but not that difficult. The pattern and mold building process took a lot of time and finesse. Selling these bits would depend on how much people were willing to spend for the parts. I use a high grade cloth and epoxy resin...not polyester, so there is some cost associated with just the raw materials. The epoxy resin is safer to use (almost no smell) and it a lot stronger than the garden variety polyester resin (I'll never go back to that stuff...it has a horrible smell). The snouts are 5 layers...two fine layers and three heavy layers for strength...it all gets layed up together so in the end it is an intimate connection.

Also...I want to thank the following individuals/operations for assisting in making this project a reality for me:

John Speake at JDS Porsche for giving freely of his time in Cambridge, England while I was in the UK last year. The ability to burn new EPROMs would not have been possible without John's unique setup.

Jim, Mark and Tom at 928 International for supplying me with the hard to find bits and pieces I needed through the build.

Oklahoma Foreign for supplying my stand engine heads

Dave and Jeannie at 928 Specialists for providing components for the build

Corky Bell and Gerhard Schruf of Bell Intercoolers for their beautiful execution of my intercooler and plenum box designs along with their excellent technical assistance...these guys hold many decades worth of turbocharged power knowledge...true experts and always willing to help out.

Bob from Bob's Braided Lines here in Cincinnati for lending his years of knowledge in line layout and design.

Joe Rook of JR Mechanical here in Cincinnati for providing excellent and on time fabrication services.

Mike Crompton from MLC Technologies here in Cincinnati

Hans and Andy for helping out with the build

And last but not least...my patience for holding out through this project.

Twin Turbo Update:

Putting the finishing touches on the oil and water systems this week, including wiring up the oil and water pumps. Not a whole lot left before I have the car running... install exhaust system and re-route crankcase breathers to the air-oil unit. Everything is falling together really nicely. It has been a very long and slow climb, but I'm sure it will be worth the wait. Typically the longer the development, the better the results.

My plan is to fire over on the stock fuel system and make certain she will operate at idle and off idle throttle with the new induction plumbing (i.e. change one variable at a time!). The car has been inop for 9 months now. Once I confirm adequate induction and adequate cooling water/ oiling to the turbos I will switch over to the "Incredible Hulk Green Top" 42 lb fuel injectors, Super MAF and cold plugs and start the tuning process.

Nothing quite like strapping down in sub 50F weather :) I should be ready to pull stumps from the earth sometime right after Valentine's day.

Awesome! keep us updated!

I'm thinking a 5.4 liter GTS with one bar in the manifold would be an absolute animal. What say ye and where is Ralph Mouth?

Ralph and i have parted ways. I am actually getting the gts inspected thursday and finally getting it on the road. too bad its winter. i am also finishing the stereo system and interior with all new parts so i cant wait for spring. im gonna drive the hell out of it. i plan to get it painted in august as well. I also say say im all in for the turbo! after you make 600hp to the wheel, then we'll do mine. ohio is not that far away you know!

600 WHP on a 5.4 liter should be easy...but I'd better wait until mine is running first!

we will definately have to meet up some time this spring.

Just let me know when you are in town or passing through.

My goal is to have the car fired up this weekend....most likely Sunday evening (I just hope before midnight) Being this close is both frustrating and exciting. There are just a few oil lines standing between inop and operational!

2000 views on this thread...WOW! I quess this means 100 people looked 20 times, or maybe 1000 people looked 2 times, or maybe 20 people looked 100 times...the possibilities are nearly endless!

Remember...you are all "verboten" from taking this information elsewhere beacuse we have big brothers watching us...and they are ANGRY! :)

Herr----

yes, I am definitely interested in the 16V set up, sometime in the near future, maybe before summer.

I am currently building a 5.0 (might overbore/stroke it) equipped with my Euro top side parts. (my 4.5 lunched a piston---kind of pointless to rebuild it when you can just drop in a 5.0.....) I'm old school as far as fuel systems are concerned, so the K-JET will remain as well. Should be around 400hp by the time I get done with head and camshaft work as well. Add a blower/turbo set up and it'll be a blast!

19 inch wheel/tire combo going on this weekend, new leather interior in the works (so to speak), new clutch hydraulics last weekend, added spoilers on both ends, complete S4 front suspension and big brakes to be installed as well.

(I know, I could have just spent the bucks on a S4, but where's the fun in that?)

Let me know as well when you get around to marketing the 16V set up.

Largecar379@earthlink.net

regards---rhjames



http://forums.pelicanparts.com/uploa...1170400428.jpg

It is possible I might be able to be talked back to 16V land. But the K-Jet...my vote is rid yourself of that one. You can't beat pulsed injectors for this sort of requirement. 400 HP with just head and cam work might be a bit positive for a goal, but if you can get it there, more power to you.

For now the focus is on 32V cars I just picked up an EPROM burner and the new chips for the car. The last welding of the oil cooler lines will be done tomorrow AM. With any luck at all I should be able to turn the key by Sunday evening. Get her idling on the stock system and then start to tune it in. Somehow I think this dial in is going to be terribly easy (Thanks John!).

Seeing as my last build on a 4.7 liter broke 450 ft-lbs and 400 HP to the tire on just 10 psig...I have big expectations for this car. 300 more ccs and starting with 320 off the crank, better turbos, better manifolds, better fuel and ignition management, knock control, etc. Everything is just more refined and further developed.

I've seen one of these turbos in .64 a/r housing support 370+ WHP on a SR20 Nissan. My housings are significantly larger than this. I'm aiming to keep my backpressure to a minimum to maximize the mid range and top end powerband on this car. The whole thing was designed for 650 off the crank with some reserve. Most of the "hardware" will support 750-800 HP by the book...but I don't think the driveline or stock internals will hold that much torque. Additionally, you have to be able to feed it when it is on the bottle...so larger pump(s) and lines would need to be installed before it could ever get to these levels.