My porsche 944 S2 16 valve turbo project
 

Hi Guys, MY name is Tim and I have had an interest in car since the age of twelve. I presently work for a company called Supreme Car Services in Peterborough UK. We specialize in Ford Cosworths, servicing, repairs and engine upgrades/rebuilds. I'm now in my early fifties and fancied doing a car for myself and as I work on Cosworths most days one of these was a no no. Has I have always liked the Porsche 944 I decided to look for one to play with.

I purchased this one thinking it was a good example.


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When I got home and on a ramp for inspection, we found the underneath of the car was in excellent condition, but there was some areas of the bodywork that needed attention. The bottom of both front wings, a small patch on rear wheel arch and a small rust spot on the drivers side sill.
I decided to let my friend Mark at Autofix 2000 in Bourne sort out the bodywork and at the same time give her a coat of paint all over. I also added a set of GT3 wheels which I had purchased and she now looks like this


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Now I do like the way she drives and handles, but thought she could do with a little more power. So I thought I would have ago at a 16 valve turbo build. Having been building Cosworth engines for sometime, sourcing parts was not a problem. Firstly I purchased two engines of Ebay, a 2.7 litre short motor and a complete S2 engine.



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I stripped both engines down to the last nut, bolt and washer. I had all these parts water blasted and all bolts etc. re-plated so when rebuilt she would look like new.
I decided to use the crankshaft from the 2.7 engine, which as a 78.9mm stroke, this I had polished and balanced.


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I had a set of ductile liners made and fitted, taking it back to 104mm bore. A set of pistons made by CP pistons in the USA at 8.2 compression ratio which should let me run some decent boost. The crankshaft journals in the block we drilled and tape to except a oil spray jet. A set of steel conrods purchased from Australia. I did away with the balance shafts and blocked off the oil ways with grub screws. This I assembled to give me what I think is a good solid bottom end.


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The cylinder head I ported, mainly just sanding away the sand cast finish and not opening up the port size as they are plenty big enough. New guides fitted, inlet valves as standard and a new set of exhaust valves made and fitted, which will except the extra heat involved. I had the camshafts re-profiled to a solid lifter setup, giving me more lift and duration.
I fitted the cylinder head using a new cometic head gasket. The biggest problem I came across was the cam timing, because of the inlet cam being driven by chain from the exhaust. I did consider buying split cams from Michael Mount in the USA but due to the cost of them I thought I would see how it performed with my re-profiled ones first. The cam timing I had to come to a compromise with, but once set I got the engine sealed up.


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The inlet manifold we made ourselves using the S2 runners and a cast plenium from a Toyota Supra upgrade setup. The throttle housing is a Mitsubishi upgrade and as a 75mm butterfly and built in idle speed control.
I used the standard S2 exhaust headers and married these up to a turbo crossover pipe. For the dyno I cut the end off this and welded on a T3 flange, so as we could try various turbo's.



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The inlet looks a little plain in the pictures, but when it comes off the dyno I intend to have it crackle blacked.
We then converted a bell housing to fit our Superflow dyno and loaded it on. The engine is going to be run on a Pectel T6 2000 ECU, which will read the 60 minus 2 trigger wheel and the hall effect cam sensor. A set of 1000cc fuel injector and 4 bar map sensor.
The wastegate is a 44mm Tial, hopefully this should be big enough.


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Once we had got the trigger wheel set up done, she fired up and ran lovely. We ran her in for sometime and pulled her at various rpm points just to see how the turbo worked. We started with a Garrett Stage 5 turbo (T350 exhaust wheel, 61mm inducer and .82 exhaust housing) capable of 600 plus bhp. It came on boost quite well with 24psi @3250 417lbs ft/258hp. 3500rpm @ 32psi 513lbs ft/346hp.
5000 rpm @ 32 psi 511 lbs ft/487hp. 7500 rpm @ 22 psi 407 lbs ft/582hp, but at 33 psi back pressure.

We then tried a Garrett T04Z @ 3500 rpm 32 psi 505lb ft/332hp. 5000 rpm @ 31 psi 523lbs ft/498hp. 7500 @ 28 psi 472lbs ft/676hp.

The engine ran faultless, no breathing issues etc.
The engine is off the dyno at the moment, I have change the size off the crossover pipe, as I feel there was a restriction at the y section.
This all complete, ready for the final mapping session and when this is completed I will post a final dyno sheet. It may be two or three weeks as I have had an operation on my foot and off work for another two weeks.


I hope you guy's find this as interesting as I have doing it. The Porsche engine is a lovely bit of engineering and I think its well up to the task.

This thread is also on the S2 forum

Very interesting project, thank you for sharing. Congrats for the excellent results!

That's a lot of boost you're pushing! A real interesting build.

I think this would be a perfect application for a GTX 3582R for the amount of boost you're pushing.

looking very nice - but one question: did you do some measurements to fit it into the car? don't think you'll get it in with the turbo in the current position...

Nice build :)

Stock headstuds at 33psi??

Glad you brought your build thread over here Tim. I actually really like the fact that you've approached it from the 'outside'. By that I mean most people that modify our cars have been either doing it for a while or building up to this sort of level. Whereas you've come from a Cosworth background and applied aspects that virtually nobody would think of doing. Namely such high boost on pump fuel and stock headstuds as DLS mentions. Some larger headers would be interesting plus a bigger turbo just for curiosity sake. Keep us posted with your progress!

Totally agree with you here, When i read this, It seems as though someone got this engine and went their own way with it.

How much bigger is big Patrick? Looks like he's got the space for a massive turbo.

Im curious about these Australian rods?

Hi, Yes done all the measurements. The turbo will not be as in picture, it was mounted there so as we could try various turbo's

Hi Pauly, We have tried the GTX3582R on our 2.2 cosworth engines, but suffered with bad surge, especially when in the car. I also thought that with the extra cc of this engine and the amount air she would need, the GTX35 would work. I had the loan of one from a friend, but we still got surge, so I didn't procede with it. I would have liked to have tried it now I have changed the crossover pipe but I'm afraid its gone back.

Cheers Tim

Any more pictures of the intake?

Hi Patrick, I had looked at having a new manifold made, but it was going to be to expensive. On measuring the headers and finding that they 1mm bigger than the manifold we run on our 725bhp cossie engine, I thought they would do the job. I do think it could do with an expansion joint in one of the runner, like the standard turbo manifold though.

Cheers Tim

Hi Doug, The engine is off the dyno at the moment and I have sent the manifold away to have it crackle blacked. I'll take some pictures when it is back on, which will also show the turbo mounted in its final position. I'll post them on, maybe a couple of weeks.

Cheers Tim

Very interesting. Great results. I would just drop it in the car and have some fun.

Always nice to see someone doing their own thing instead of what everyone does around here.

Very very cool. I am so glad you are thinking outside the box on your build.