Question is simple, how high can I run the compression and still be able to use 94 octane (even though the car will mainly only be running 100)

 

i'm running 12.5:1 on 94. I haven't tried running higher, so i'm not sure how much more you can go on 94.

 

depends on tuner and tuning method (i.e., engine management). I am NOT A TUNER, with that being said, my best educated guess would be around 13:1 on 94 pump and you still may need to be light on the throttle.

Who tunes your car, your best bet maybe to ask what they recommend.

 

20:1 with the right cam.

Static compression has just about nothing to do with octane requirements.

3 words - dynamic compression ratio. That means we'd need to know what you're running up top (cylinder heads, cams, etc.) along with what you're running for a bottom end (crank, block, rods, etc.).

It'd be nice if someone can start up a database with dynamic compression ratios and octane requirements for 4 cylinders. I know what a reasonable dcr for a larger displacement 16 valve V8 (300 cui +) on pump gas is but it might not be the same for 16 valve I4.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by backpurge &raquo;</TD></TR><TR><TD CLASS="quote">20:1 with the right cam.

Static compression has just about nothing to do with octane requirements.

3 words - dynamic compression ratio.</TD></TR></TABLE>
thats a good point