I posted in the 944S2 section but maybe should have been here...

Hi folks, thought I should share the progress made on my 944S2 cabriolet turbo conversion, I have been able to get a lot of help in making this conversion from the web in particular the Rennlist/968 web folks. So hopefully I can share the outcome that may help others down this route.

First the goal, I wanted about 300 RWHP, keep stock driveability (I commute in Sydney traffic each day), no bling just wanted a stock look and sound. But much faster!

Outcome so far exactly that, it has also been a very low cost exercise relatively speaking to the power gain.

Approach, stage 1 was stock compression and 8 psi max boost, stage 2 9.2:1 compression and 10/11 psi boost have got a Cometic 3mm HG (not there yet)

Stage 1, I first built a new inlet manifold that would allow me to fit the turbo a T04B-60-1 HiFI, KKK#8 and stage 5 wheel, this took me ages to select this combination using a mix of calculations and feedback from turbo companies and other owners, it may not be the best, but it is pretty close i think.
The manifold took about 3 months, using a donor 951 and 944S2 manifold, a lot of time matching and grinding to make it flow, there is a lot of measurement and fabrication needed if your not handy dont attempt this, I used an external company to do the TIG welding, so all up it cost about $1,000 to do. Happy to share measurements with interested parties.

Tapped the balance shaft housing for the turbo oil supply, and built new fittings for the supply and return was quite easy but needs accuracy and care.

Now all the fab was done, I mounted the turbo, with 951 turbo engine mount, didnt connect the exhaust cross over yet. Mounted the new manifold, rebuilt 951 throttle body, intercooler, made some new custom fit alloy hard pipes. In that process removed the flapper door AFM, mounted a seperate IAT on the inlet and wired in the new standalone a 4424 from http://www.enginemanagementsystem.com/ in hindsight I should have gone for their next level up 4860, but this was a easy to use EMS and I learnt a lot from it.

So what I had then was a stock 944S2 3.0 motor with a turbo non operational, new manifold, new throttle body and new standalone EMS.

I then spent the next 3 months making sure the ignition and fuel were right, in all conditions, hot cold startup etc, well worth the effort it runs as good if not better than stock Motronic EMS. I also did the base line setting for boost with a very conservative ignition map and rich AFR under boost - theoretical at that stage, quite easy to calculate and set.

Next step fit the 951 crossover, had to do a lot of cutting and fitting to match the headers to the crossover plus some outsourced TIG welding, not much cost in this just time.

Used a Tial 44mm wastegate, this is important IMHO as the wastegate will get a lot of flow as the boost is low and it needs to bypass a lot of air from the T0B 60-1, used V band connections to mount the wastegate and then into the exhaust.
I used a company called MC Motorsports in the U.S to make me some custom flanges mc_motorsports@hotmail.com, great service and very cost effective. So I went for stage 1 a 2.75" from the stock downpipe to cat, later stage 2 I have a 3" downpipe, 4" cat and twin 2.5" exhaust planned using MC's custom flange.

Boost is set a 4.5psi using the wastegate spring, I have electronic boost control on my EMS and that is set up so I can increase boost slowly as I get the tuning and AFR right.

So right now, a low boost, high compression 944S2 cabriolet, all up so far about $4500 exluding my labour which was huge and I had a ball doing it.

It must be about 300FWHP on the low 4.5 psi boost, I expect about 370 FWHP on 8 psi and 400 FWHP on 10psi in stage 2, that is very likely at the top top limit for the stock engine - who knows it may be beyond it and may break!! Time will tell. I do run a reduced rev limit using my EMS set at 6200rpm.

Here is the car at 2 months ago it has been cleaned up since, I was working the cold start and ISV control at the time so I had the ISV temporarily mounted on top of the manifold so I could get to it. I have also got rid of the external weld marks on the manifold so it look factory now. Still a few more cosmetics to go.

Happy to share the experiences if it can help anyone.

Bottom line though - you can turbo a N/A, it will be fun, it will be very fast and it doesnt cost an arm and leg, but I will admit there are better ways to do it but the cost will go up significantly too.

rgds
mike

 

dont know what I didnt do right there no image - hopefully this works.

 

awesome!

 

That is VERY clean. Nice work! Bet that pulls like a champ!

Any thoughts of heat shielding for the brake booster and MC?

 

Yep, I have the downpipe & crossover wrapped and also a turbo blanket on order from Garrett for the hotside, it should be lower temp than stock 951.
rgds
mike

 

thats friggin awsome!

 

Can you come on over this weekend and help me work on mine?

 

Man! Such a clean and very well laid out engine bay you have. So simple-ized compared to a 951!

Any shots of the whole car?

 

Great work and looks awesome! Finally another person to tell those " sell your n/a s /s2 and buy a turbo" the way to go if you like to work

 

Hi CarbonRevo, here's a couple of the car.

 

Beautiful car! I *really*, deep down wanted a Cab., but they are certainly hard to find. I got very lucky finding this '91 S2 in my area.

I definitely think you should put a Turbo emblem on the back of the car!

Also, what exhaust is that?

 

Beautifully done! The work looks exemplary!

Does your car have ABS? Noticed the brake bias valve right there on the brake master cylinder. I thought the ROW cars had ABS after 87 too.

Cheers,

 

Wowie! Me is in love!

 

Carbon Revo, I thought about badges, but my goal was really factory - stealth look, no one has any idea of the potential of this, a sleeper really and I am happy with that. The only thing I have weakened on was the number plate and my son was the one who convinced me to go with that.

Riff, mine hasnt got ABS wish it had, its actually the 1989 built model so doesnt have a few of the nice to haves, like ABS and cruise however, but for Australia I have A/C which is very important!

rgds
mike

 

Very nice car!
Glad to see you went (more precise, stayed) 16valve way and not converted it to 8valve. I like 944 Turbo Cabrilets also but this is so nice approach!
You should get some engine management also for Stage2 with lower CR.