I posted a question like this before and unfortunately no one answered it. So, once again:

I know that Jun 3 cams like compression, and that higher compression is the way to get the most power out of them. So, I would like to raise my compression. I was thinking of going with 12.5:1 compression, but I want to run on 91 Octane. Will this work? If not, what is the highest compression I can run on 91 octane?

 

if you retard your timing and tune your car correctly, its possible. 12.0:01 would be more friendly

 

It depends on how rich you tune the motor to run.

 

In my experience anything above 12:1 will yield very good results with JUN 3's. Of course you will need some 310's and a good ecu program to go along with it. JUN ecu is great if you can get one for a good price (which I do, and am selling -shameless plug lol) or Hondata of course.

 

i run jun 3s with 12.2:1

its okay.. have to run 12 degrees timing with stock fuel pump / injectors @ 53psi at idle w/ the fpr.

 

Tuned right, you can get away with 13.1+, especially with long duration cams.