Re:Does a vtec head really bump compression?
 

the y7 and y8 have the same volume for the combustion chamber= 34.0 cc, so the CR will stay the same.

The z6 is abit higher, ~35.5cc, and the 4th gen heads were 38cc.

This is all from memory. I'm gonna throw on my y7 head od my d15b1 = about 10.5~11:1 CR, until my spare motor is ready for tuning. I'm using y7 pistons in a D15b2 with the b2 head to make around 9:1 CR, probably a bit under that. The Mini-me swap on a D16y7 gives no compression bump though, just VTEC.

Re:Does a vtec head really bump compression?
 

Thanks for the knowledge. :) I'm gonna be doing the swap when I pull my sohc out to build it up. :-*

Re:Does a vtec head really bump compression?
 

well its finished and im amazed at the difference between a a6/z6 head and an a6w/y8 head. the y8 combo has a lot more torque and vtec screams! definatlty worth the 300 bux im spent on the whole thing.

Re:Does a vtec head really bump compression?
 

vtec has nothing to do with the bump in c/r, just the volume of the head, as you can see with the 4th gen heads he was talking about (38cc)

bump for a good topic though, i would of gone z6 head personally, better ports, but the y8 has the most aggresive cam, (shrugz shoulders, it's a toss up) :-\

Re:Does a vtec head really bump compression?
 

I have a d16a6 with d15b1 pistons mated to a z6 head...what would that bump my c/r up to if a stock a6 block and z6 head make over 10:1 c/r, and the b1 pistons are flat tops instead of dish(plus the b1's sit about 8 thousandths over the top of the deck)?