Possibly a stupid question...

[Ethereal Zer0]

What is the highest compression ratio I will be able to run on pump gas (92 Octane) and not have to worry about detonation?

 

[S/CBlack95GT]

Usually if you run the timing at 10 degrees intial you can get away with a 10.5:1 CR. It really depends on the timing though.

 

[Ethereal Zer0]

Thanks! If I retard the timing, would I be able to up the compression? I'm thinking about building a 393 stroker, but i am undecided on compression ratio. It will be an everyday driver so its gotta run off pump gas, but i'd hate to miss out on more power!

 

[GTPhreak]

The cam has alot to do with how high of a static ratio you can run

 

[95GTvert[bv12]]

also the heads play a big part in what octane you can safely run.

 

[Joes95GT]

My Dad's old 69 Mach 1 ran 12:1 compression and he had the heads milled another .020 over, so he was closer to 13:1. He had almost a .600 lift cam with a 235/238 duration @ 0.050" lift, and it ran perfectly fine on 93 octane with 4 degrees of ignition timing. If he advanced the timing up to 12 or 14* he'd have to run 100 octane. Even with the 93, the car ran low 11's.

A safe compression to run on the street is 10.5:1. You can still run plenty of cam, and a pretty aggressive base timing setting.

Joe

 

[Ethereal Zer0]

Awesome, thanks guys!