Thread: what do you guy think the highest compresson i can run on pump gas

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9.5:1 on 93 Octane Max

I run 10.6:1 compression in my 383 and have no problems if I run 91/92 octane. In fact, I had to fill it with 89 octane in a pinch two weeks ago, and still no pinging. My DCR is 8.46:1 which is getting close to the 8.5 edge. But with AFR heads, less timing is more, and 32 degrees total made the most hp and torque. I originally wanted to run a CC XE-274 cam but it put the DCR at 8.67. But the Magnum 280 cam put me under 8.5. I am very happy with my engine combination.

I ran 92 octane in a 11.3:1 350 +.030, nasty solid cam, iron heads ported and polished.

I had to index the plugs to get rid of pinging.

IMO a water injector would get you over the hump, and they are not too expensive nor are they a pain to keep up.

Kitz