964-C2

I hear the Vulcan Cut-Ring is the best head gasket for a 951 now. I believe this only comes in 1,6mm-thickness versus 1,0mm for the stock gasket.
Isn't that correct?
This will give a CR (compression ration) that is about 0,3:1 lower than stock, which does not sound very good to me.... (less off-boost performance).
What are your thoughts about this?

V2Rocket

youll never notice.

fejjj

This is a non issue and I have them available if interested.

Oddjob

Decreasing compression ratio seems to be going in the wrong direction. I didn't do the math to confirm the volume decrease, but a 0.3 reduction in CR would show up in a dyno comparison.

We used to get our heads shaved 20+ thousandths to increase compression ratio. PCA started measuring head/deck height to catch anyone running less than factory rebuild specs. So would need to run a thicker headgasket to keep using the shaved heads.

If concerned about losing a couple hp, and planning to use a thicker head gasket going forward, you could get some of that difference taken off the head to compensate.

964-C2

Ok, thanks for your input.
The porsche manual say you should use a thicker head gasket if/when grinding the cylinder head down 0,2mm (or more). This must be because of the change in timing and compression ratio, right? In regards to that, it sounds like it matters a lot if I will be installing a 1mm (stock) or 1,6mm (vulcan) head gasket...

333pg333

That reduction in c/r could be mitigated by an increase in boost all things considered.