i am planning to use a Y7 head on an A6 block. is it safe to presume that the head is identical in chamber volume and design as Y8? what C/R am i to expect from the combo, using stock A6 pistons? what about with A1 pistons? i need to know the ratio desperatly as the motor is going to be FI, and i am allowing the C/R to be 10:1-11:1 maximum with moderate boost level. stand alone (Zdyne, most likely) will be used, as well as B18 H-beamed and shot peened rods. so i assume 10-12 pounds it will hold. any help is appreciated.
stan

 

The Y7 has the same size combustion chamber as the Z6 head, 34.6cc whereas the Y8 head has 32.8cc combustion chambers.

I believe that compression is 10.6:1 with y7/z6 head and 11.2:1 with y8 head (I'm running A6 pistons in my Y8 motor). This is due to the smaller sized dish on the top of the A6 pistons and they are actually taller (greater compression height).

 

thanks for the reply, i know this is all a rather technical info, so i appreciate it. do you know what D16A1 pistons (integra motor) will result in?
how does you motor behave? what octane are you using? i have plenty of questions , so keep that info coming!
stan

 

A1 pistons are domed, and i think you have to get the valve reliefs machined to clear the valves, someone needs to clay them and find out...they make 12 or 13 something I beleive, I'm not too sure.

I'm running 93 octane fine, no problems and I'm just now breaking in the motor (60miles on rebuild), after I get my timing issue solved I will be driving it more, but the compression is already at 150psi across the board, and I haven't even begun to seat the rings.

 

hmm, sounds like A1 are out of the question then, again thanks for all the info, good luck with your project
stan