RSflared72e

Looking for opinions from folks with direct experience of turbocharging 3 liter 16V engines (in this case, my 91 S2). This will NOT end being a 500 HP grenade engine, the goal will be an occasional DE event street car with a modest increase over typical 951 power, perhaps into the 300-350 HP range. This shouldn't be too tough with a 3 liter turbo.

In reducing the compression ratio, new piston$ are of course my (technically, not financially...) preferred route.

Main issue here: opinions seem to vary about how much wiggle room is available in the stock S2 pistons to dish/machine them down to a reasonable CR but with adequate piston thickness remaining.

Otherwise, this particular car seems to have a very solid bottom end; no running problems and the original rod bearings had virtually no wear. The head will be undergoing a full P&P/rebuild. Will address intake manifold & turbo plumbing and selection along the way, of course.

Other questions: who has the best (if any) wide-fire-style head gasket for this 3 liter application - Powerhaus, etc.?

Necessity of Carillo/Pauter etc. con rods?

Regards Al

pete944

Your best bet is probably to call Powerhaus or John Anderson.

RSflared72e

Powerhaus wants to sell pistons...I'm hoping to hear from someone without a sales agenda...

James86-951

I would think you could run the eng essentially the same, but just low boost pressure. (~5in Hg) You definately need to talk to some of the Gurus in that area.

pete944

Powerhaus can be pretty snooty. I think John Anderson at <a href="http://www.andersonmotorworksinc.com" target="_blank">www.andersonmotorworksinc.com</a> is the guy to give you the answers you need.

Mike S

Another less expensive...although not preferred method would be to use a thick head gasket. One say twice as thick. I've seen V-8's drop as much as 3/4 of a point of compression with thick head gaskets. Perhaps guru racing or john anderson could have one made for you based on existing designs.

RSflared72e

Yeah, we've batted around the idea of thicker head gasketing as well...seems the least robust way to go, and I'm not personally aware of anyone who's gone this route specifically with this engine type. I am trying to avoid going where no man has gone before, as much as possible...however any significant CR reduction is a step in the right direction. I imagine in this non-race application 9.0 or even 9.5 to 1 might be low enough.

CarreraCup03

The s2 pistons are cast .. u should at least get some 968 forged pistons. I had a s2 turbo engine with 968 pistons and shorter rods. It will work .. but again not the best way to do it. Call Dwain at Vision (Kokeln) .. he has done tons of them this way.

944turbo

Fishey

Hmm, See why does the Porsche manual say there forged piston's? why do they weight less? ok, Just an observation but everybook says there forged look at a craftsman forged wrench? looks alot like them the pistons smell forged look forged... I dunno but I am thinking there already forged pistons.

Here is an Idea on a more powerful 944s2 engine.
6angle valvejob, P&P, Chip, Cam, Ignition, Wires, Intake , Exaust, 0w-40 oil... That should make for some more power? around the 280hp mark..
+50hp from the nitrous Oxide and you will still be cheaper then a turbo system..

Robert D

Having a turbocharged motor is cheaper in the long run than refilling the NOS system isn't it?

RSflared72e

Ha - I was actually going to post a separate thread - guess I still will: are the S2 pistons forged? This has also been a topic of debate as I contemplate this project....also makes a difference in whether to machine the existing pistons vs. buying new low compression Mahles...

Fishey

nope.. turbo kit for normal car what $3,000? and for the 944 its like alot alot more. So, Nitrous kit is 500 plus other things you will need make it $600 and at $50 a 10lbs refill thats 40refills and only $2600 witch is cheaper then $3000 and I am guessing in a lifetime 40 refills would be hard to go through.

mmmbeer

For a low boost engine you do not need to lower the compression at all.

The chaepest (respectable) way to lower compression is to put in a 2.5L crank which will result in a 2.7L engine with 7.6:1 in compression.

The next cheapest method is getting just the shorter rods and keeping the pistons. Specially made rods from Carrillo are about $1200 for a set of four. 2mm shorter would give a compression of about 9.2:1 while 3mm shorter will give a compression of about 8.5:1 (according to a Carrillo salesperson). This is date for the 968, but the S2 is very very close to the same.

I do not know if the S2 have forged pistons but if it does, there is not urgent to replace piston.

Regards
Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>

RSflared72e

Just talked to EBS, they say they can get custom shorter Pauter rods for $800 for a set...

John Anderson

There are pictures of an S2 on our website, it hase been thru SC to Turbo charging, on the same stock bottom end. It now has about 15K on the turbo conversion without any problems at all. Infact we are going to install shorter Pauter rods to reduce the compression a tad and run a little more boost. Stock engine is great on these cars.

I'll post a link to some video of this car getting hammered on the dyno this week.

<a href="http://www.andersonmotorworksinc.com/internal_pages/conversions.htm" target="_blank">http://www.andersonmotorworksinc.com/internal_pages/conversions.htm</a>

Take care!