944 3l heads versus 2.5l heads

Anyone know what the combustion chamber size differences are and if you can bolt a 2.5 8v head to a 3l short block?

1989 8v 2.7L used the same block & bore diameter as the 3.0L but shorter stroke. I believe that the head had larger valves than the 2.5L. Not sure about the 2.5/3.0 head/block combo.

FYI: Lindsey Racing should be able to answer that question.

Lindsey Racing has been dropping the ball lately, customer service and quality wise. Hopefully you'll get a decent answer from them.

I have a race prepared 89 2.5 head and a 3.0 block. Thinking of building a 3.0 l 8 valve but I am wondering if the compression will be to high.

I don't have a 3l head to cc nore do I know the volume of the oe piston reliefs of a 3l.

Then there is the whole issue of if the 2.5l head will actually work on the 3.0 block. Water jackets and oil passages need to be looked at.

I suspect that at a minimum I will need 93 octane but who knows.

Do what they did before the Internet existed...measure

chiodos wrote: Do what they did before the Internet existed...measure

Hard to do if you don't have a 3l head on hand.

I am going to look up the cc numbers on the 2.5 race head I have. I cc every one I get and balance if needed befor assembly.

I was a bit OCD with my race motor builds.