cc'ed my motor check my math....

[Z3_GoCar]

Since my motor needed to have some material taken off the deck. So, I figured I needed to check the static compression ratio. It was originally built by Alan Jones for TC Kline's World Challenge team in January 2001, so it was a bit of an unknown, other than the 84mm piston overbore. So here's what I measured:

Piston dome and a compressed 0.070" head gasket measured 7.2cc
The head measured 36.8cc
So the total top end measured 44cc

The bore has been enlarged 0.003" so it's now 3.310" or 84.074mm and the stoke is 84mm, so the swept volume is 466.329cc. So the effective compression ratio is now 11.6:1

Now come the reason I'm asking for confirmation....

To get the Compression ratio back to an IT legal 10.7:1 I determined I'd need the head gasket to be about 0.029" thicker, maybe a little less because it's not perfectly circular, but for the moment let's just assume it is the same diameter as the bore. The equation I solved is:

10.7 = (36.8 + X ) + 466.329 / ( 36.8 + X) => X= 11.275cc

So, I need to increase the head gasket thickness to gain ~4.1cc
so assuming the head gasket is cirular and the same diameter as the piston I get an increase of 0.07385cm or 0.029" Does this sound reasonable?

One final item to discuss is, anyone run a multi-layer steel head gasket? I was orginally planning on running an oe gasket, but the only source of a thicker oe gasket is Victor-Rienz, which are known to not last under race conditions.