What Compression ratio on Blown 4.6?
 

Im sure somebody may know the answer to this. What compression ratio does a 4.6 with pi heads and a vortech with 8-10lbs of boost need? I was thinking around 9.5 to 1 but not sure. I was wondering so i know what cc pistons to get.

Thats a pretty good ratio to go with. Just have to keep a closer eye on the plugs and the type of gas you use.

If you are buying new pistons and this is a street car I would get closer to 9:1. 10 psi on a 9.5 compression motor is going to need a lot of timing removed out of the tune

Just throwing this out there, but the Lightning's run 8.4:1 stock with 8 psi and 91 octane or better. It may not be relevant to your question though.

There is 3 options lol