There is no reason to run 93 octain on a 8.6-1 motor unless you have an advanced curve kit in it or are running a bunch of timing to it. If you have it at stock timing it will run just fine on 87. If it doesn't ping, it doesn't need better gas.
No need for 93, 87 will work fine just like Jet said. Its an added expense that isnt necessary. The only way it will ping is if it is full of carbon or oil leaking past the rings/valve seals. Ive run 9:1 455s on 87 without issue, so a 400 at 8.6 is no problem.
I don't know. I have a low compression 455 that seems to run much better on 91(best we have here) than it does on 87 and better yet when I run an octane boost with the 91. The motor was rebuilt right before I bought it. Bored .030 with a mild cam. No specs on the cam.
I guess my recommendation would be to run 87 and 93 octane and you decide what makes it run the best. Keeping in mind that 93 octane will not hurt a thing except your wallet......
Performer Intake, Mild Cam
Pertronix Ignitor III
Accel Super Coil, Accel 8.8mm Wires
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