im just wondering the difference between these motors the y8 is sohc vtec also right? is there a major factory horsepower difference or why does it seem that more people want the y8 over the z6?

 

im very intreseted in getting this answer!

 

The oil pumps on y8's shit out on you and you'll end up spinning rod bearings. Watch your ass.

z6 > y8 imo.

They're both capable of the same power from what I've seen. What car is it going in?

 

i have z6 in my eg6 right now and im getting ready to boost i was going to swap to y8 if it was any better but i guess not! will the y8 head fit a z6? i need a head and cant find good z6 heads around here!

 

your z6 distributor will not bolt to a y8 head. the y8 head has smaller combustion chambers the the z6.

 

I have always been told that the extra metal in the y8 head, makes up the quench area.

Its supposed to squirt the a/f mixture to the middle of the combustion chamber for more efficiency.

Its said that it also helps to suppress predetination by keeping the a/f mix away from the sides of the chamber where hotspots might develope. i believe its called a pentroof style chamber. the b18c5 head has a similar chamber. the intake runners on the y8 head are not straight. the port splitter is angled to create a swirl in the chamber for better efficiency.


Also, you can boost the Y8 no problem, but if you do pick up a Y8 I'd re-shim the oil pump or buy a high flow, because those oil pumps are really restrictive and don't give the proper lubrication under high RPM's.

You can use the Y8 head on a Z6 but the head stud issue, the upper left stud on a z6 is raised where as the y8 studs are all the same height. Meaning you would need to use 9 y8 studs, and 1 z6 stud or it will strip the threads in the block when you drive the car.

 

i have the z6 right now and i was told that it got rebuilt right before i bought it but when compression tested i only got 135 psi across all cylinders? i thought stock was around 180 psi!? would it still be safe to boost this motor with no more than 6 pounds and tuned on crome?

 

any more advice out there?
thanks for everyones help so far!

 

How did you do the compression test? Did you turn key till compression tester needle stopped moving and had throttle fully open ?

 

i tested until the motor had went through 7 comp. strokes on each cylinder, but with throttle closed. does it make a diff.?