michaelmount123

What's the question? Stock S2 vs. 968? I've forgotten.

Dutch944

What the flow numbers for the Stock S2 head are as that will be the closest to what i have at this moment.

michaelmount123

Here's a 944S which is very close to an S2. The S2 is probably a little better due to more distance from the valve to the cylinder wall. All at 28".

.100 102
.200 207
.300 284
.400 304
.500 312
.600 318

FYI, here's the same head after race prep (not full port):

.100 101
.200 205
.300 290
.400 326
.500 339
.600 344

There's a ton of potential power in these heads, especially boosted!

blade7

S2 pistons I think he said when I asked on here, something doesn't add up, why are engine builders throwing away S2 pistons and using Wossner/ Mahle etc if machined S2 pistons can take the boost ?

Kris H

i don't know any details of that build, but i guess coating pistons may have done the trick..

I was also suggested that for my 2.5 16V turbo, i may use stock 944s pistons ground a bit to reduce CR instead of going for aftermarket forged ones, or instead of modifying 951 pistons.. I'm not entirely convinced, but if it's confirmed to work, i may end up trying that.

Dutch944

Once again Michael, you are my hero!

Seeing this and than thinking about my buddies unported VR6 head which only does 180cfm at full opening and running 450hp.. I can only see a lot of HP coming!

Raceboy

Weak point of 944 engine is it's cylinders which start to dance around when cylinder pressures (=power) go up..

Dutch944

Only with the 2.5 enginer.. The 3.0 is siamesed!

refresh951

They still move.

blade7

Coated where exactly, on the crown ? Plenty of people raved about this engines output when it was posted about on here but it seems there is no concern about using the cast pistons ?

KSira

Since cylinder pressure i equal to torque, there should be some gains by increasing boost with rpm to keep the torque constant. Not that it is falling much on my 16V turbo, but still might be an option for some.

michaelmount123

The 2.7 head would definitely be better than the 2.5 2V. It's got a larger intake valve (major impact), and bigger intake ports. I can't quantify the difference, though. Has anyone flowed both on the same flow bench?

V2Rocket

not sure how well it translates into the material used in the alusil-OK pistons but in the iron-block world cast pistons are strong but can be brittle and get f*****D by detonation whereas forged can take the beating better (only to a point of course) so your tune must be spot-on!

thingo

I've got some stock numbers, same flow bench:
951
0.100 51
0.200 116
0.300 155
0.400 177
0.500 190

2.7
0.100 58
0.200 128
0.300 185
0.400 206
0.500 228
0.600 250

Thom

FWIW I got pretty much the same numbers from a spare stock 2.7 head (at 28" WC).