How much compression can I safely increase from the stock compression, if I am going to use just Super Unleaded (91 Octane in Kalifornia <img src="gr_sad.gif" border="0"> ) and Cal's desert weather (up to 120 in the desert summer, down to -10 in the winter).

I like to increase compression to gain back me some more low end torque after I do my head and cam job. <img src="gr_stretch.gif" border="0">

 

Our weather in Houston is comparible in the summer. I can tell you from experience that:

-My 11.0:1 cr motor pings on 93 octane with catalytics installed, in 5th-6th gear load

-It never pinged on 93 octane with the catalytics removed

I'd stick with 10.8:1 cr or less if I had to run 91 octane and catalytics. Of course, this also has to do with your cam selection because it is your dynamic CR that matters more, not the static CR.

Tony

 

I am looking at a MMS 224 Cam with their Stage II or Stage IIx head, and have MMS computer dyno tuned the car.

 

I have the 2x heads (11.3:1) and 224v3 camshaft with no cats and MMS tuning. You have to run less timing but wind up making about the same power. The nice thing about the x heads is you can have MMS set the car up for racegas by adding a couple degrees extra timing once the computer is reset.