Raceboy

It's been a while and the progress is kinda slow on my project car, but here's a little update.
Finally received the 944 S 2.5liter head, new stainless steel valves, full radius cut (not 3 angle etc) and machined seats, new guides, new stems. Exaust ports ceramic coated and intake ports and valve seats got small improvement in flow.
Photos are taken with a cell phone, so some are semi-decent quality, some are crappy quality

Head just before installing the valves:


Combustion chamber:


Generously flowing intake port, these are HUGE on Porsche 16V heads:


Ceramic coated exaust port:




And here's the head with valves installed:


This is the turbocharger for this engine, meet Holset HX40:

blown 944

very nice. It should be quite the ride

Raceboy

We'll see that when it will get the engine under the hood and drives But I hope so, otherwise too much effort is going down the toilet.

toddk911

Is that head a direct bolt on for the 2.5 block with no other changes needed?

Raceboy

Yes, as far as water jackets are concerned. I have yet to confirm stock 2.5 8V head stud length but measurements show that there's no problem.

blown 944

what pistons are you going with?

Raceboy

I'm going stock 951 pistons and forged rods. Clearance shouldn't be an issue, but I'll triple check it and I can make recesses to pistons also.

333pg333

What engine management are you going to use?
Those Holset turbos seem to have a good reputation. Keep us informed of your progress.

944obscene

I too am interested in this. I consider the 8v head a major restriction, even on the stock motor. While it may not be, I disagree with Porsche's persistance with the 8v head, even in the late model turbos. I'm sure I should search, but what all is required, aside from timing belts and pistons? And what about an intake manifold?

BC

How does a holset compare to say, a garret or a precision turbo?

BC

How is VEMS coming along Raceboy?

blown 944

My experience after building over 10 garretts. Including 360 degree thrusts. Also building 2 Holsets and looking at the internals of both designs.

The Holsets are superior IMO . The bearings are beefier, the thrust pieces are beefier, the turbine shaft is far larger, the wheels are meant for high pressure as well the compressor housings.

Other than not being DBB I can't think of anything short of wheel design that could really compare.

95ONE

I've always wondered why there aren't more S head swaps. Completely swappable from a 2 valve to a 4 valve. I just learned how simple the swap was a few months ago and it blew my mind I hadn't seen more. All else same. Trouble with intake and exhaust I guess. I forget sometimes how easy it is for me to just weld something up.
Maybe from being in the 4 valveHhonda world for so long I guess?

Awesome project. Please finish it as soon as possible. I'll risk my turbo knowledge with a guesstimates of power (With full management) should put you about 335-360 @ 15psi.

Raceboy

All manifolds are custom. Intake is already complete, even though the engine is not in the car yet. It's a twin-plenum manifold and I used stock flanges and 80mm of stock runners. I'll take the pics of it soon.

Exaust will use just stock flanges and tubes welded to them. Turbo will be in the right side.

Engine management? VEMS of course

And that engine will be sitting in 83' 924 (together with S2 tranny).

I'm hoping to be in the factory power output of the similar engine ('81 924 GTP on LeMans with 2.5 16V turbo), 420 hp @ 1 bar of boost. But, who said the boost will stay at 1 bar

If all goes well, car will be running in the summer 2009.

95ONE

I think you're aiming a bit high for a 2.5 with 8:1 compression, but it should be much better than the 2 valver at 15lbs.