Anyone running 9:1 or higher on the street? Options

[-JR-]

I'm still hashing over compression ratios. I've been reading online that these motors don't or won't run compressions as high as 9:1 without taking extra steps. Like aluminum cylinders or electronic fuel injection. Mainly just because of the heat involved.

Has anyone "got away" with running higher compressions like this on stock cylinders?

*** IF anyone has any feedback on what fuel grade they are running at their higher compression and if they are getting any knocks ect... I would also greatly appreciate that information too.

Thanks everyone!

James

[Jake Raby]

In my testing and experience I have seen that inadequate CR for the combination makes MORE heat than too much CR! I have seen engines with compression so high that they would barely start not run any hotter than a low compression pig!

The LEAST compression I run is 8.8:1 with any of my combos except for bus engines and they set up between 8.0-8.3:1!

The key is the right camshaft and the rest of the combination to make the engine easier to tune and more seponsive to change..

Low CR is the WORST thing that can be done to these engines. It kiolls efficiency to the point that EGT skyrockets and thats very hard on the exhaust valves and seats.