In some of the other posts we were discussing about how the compression for a turbo setup should be around 8:1 in order to run a large amount of boost (like 15-17 range). So I started to wonder what the compression ratio was for the 3.4. I'm guessing that it's probably close to the 2.8, put maybe I'll get lucky and it'll be at the magic number. So anybody that's done the 3.4 swap, or knows about the engine, please let me know. Thanks, Joe

 

9.0-1

Check here for more specs

 

I thought it was 9.2 to 1???? Thats what I read about it.

 

According to GMPP it's 9.0, when it's a new long block (crate engine).
I know my Firebird 3.4 engine is atleast that 9.0 compression. I registed 175+ on each cylinder, as I adjusted valves.
I believe the 3.4 in my Blazer will register very close to those specs, too. That's a 50K mile engine I've installed in that vehicle.

 

What is the next piston up as far as ratio, I don't want to have custom ones made but would like a little more then 9 to 1.

 

depends on the head CC

just use a thinner gasket or better yet, just get your heads shaved