Can anyone tell me the pros and cons of changing to the Y8 head on my Z6?
It is about ready for valve job, and I have an excellent Y8 head.
I don't want any compression issues or anything like that because the car is driven 200-250 miles a week and needs to be dependable.
Thanks,
Ron

 

there are slight differences between the two heads, but swapping either will not gain you zero...

people have said that z6 ehad do flow better, specifically for boost applications???

 

x2 there is a small difference in flow between the z6 and y8, the z6 flows better then the y8 but you will not gain/notice any power difference...you are better off getting a mild port and polish.

 

if you do end up doing the swap. you'll need y8 head bolts with 1 z6 head bolt. i have pretty much the same setup in one of my cars. z6 bottom bored .25 over with vitara pistons and a y8 head. its just waiting for a turbo to be bolted onto it.

 

so is the difference in CR between the 2 from head gasket or piston design? i know its not much difference in CR, im just curious where it comes from.

 

the difference is from the quench chamber aka the amount of space the mixture of fuel and air is mixed in.

 

does it affect CR?

 

yes, i think because its a like a flat spot spot on the head..??
well i think it does..lol idk i rember reading a huge thing on it here a long time ago

 

I think a "quench pad" is actually the flat spot on the top of the cylinder head to direct fuel/air to an optimal position in the combustion chamber for better burning....I don't think it should affect your compression though. Not sure if the d-series actually had enough of a true "quench pad" to even worry about for a dd.

 

The main thing I don't want to do is, too much compression, or not enough.
I love the mpg and buying good old cheap regular gas.
I'm looking at 400 for a rebuild on the Z6 head and the Y8 head has 46000 miles on it, so I shouldn't have to have valve job on it. It has been stored for about 4 years now. The engine broke rod and took out bottom end but no damage to head. Friend gave me the complete engine, so I have everything I need, but still, I don't want too much or too little compression.
Thanks,
Ron

 

easy. http://www.zealautowerks.com/dseries.html