Ive searched everywhere but all i can find is specs for chevys, fords and mopars..

Once the head is milled, the CC's in combustion chamber are lowered.. So my question is what is the ratio?

I saw on the domestics boards that with their larger chambers theyre ratio is 1cc per .005 milled. 78-84cc for those guys.

Now our CC's are close to half of that..So ours would be close to 1cc per .010


anyone have any real information or maybe a link.

Our search function brings up any and every thread with CC, milled and nothing with solid info

 

Formula for volume (V) = pi * r(2) * h, so V / pi * r(2) = h

Stock cyl size is 81.5mm, or 8.15cm, and 1/2 of that (radius) is 4.075cm

3.14159 * 4.075 * 4.075 = 52.168, so h = 1 / 52.168, or .0191cm

So, a 1cc slice of the cylinder that is 81.5mm across is .0191cm, 0.191mm

Or .00748 inch

Since the head has quench areas, it's not a perfect cylinder, so I'd expect that figure to need to be increased from 7.5 thousandths to really reduce the volume by 1cc.

So - your figure of 10 thousandths sounds pretty good.

 

You're on a p8r iirc, you should be able to take .010 off no problem without getting into the quench areas. So yeah, the above seems about right. B20 maths:

84mm bore: pi/4*d^2*h = (~)3.14159/4*84^2*.010*25.4 = 1407mm^3 = 1.407cc

84.5mm bore: 3.14159/4*84.5^2*.010*25.4 = 1424mm^3 = 1.424cc

 

You'll want to be sure that the distance from the piston to the quench areas remains at least 30 thousandths, ideally 40, from what I've read.

The stretch of rod bolts means that at high RPM, the piston will move closer to the head, requiring a buffer space to avoid hitting the head (also reduces piston to valve clearances).

The P2V is more of an issue with higher cam lifts (aftermarket) and altered timing.