What octane fuel are you guys running in stock 330hp 454s.

Thanks.

89 should be OK

87 should be just fine also. My 496ho's only require 87.

87 is the minimum but 89 should give you slightly better performance and is better for the motor all together.

87 octane is minimum and running any higher octane is waste of money and will possibly hurt performance and for sure will not help performance.

Agree

Will 93 octane hurt a 454 Mag EFI, Griff?

No,,but not needet !!! 87 is just fine !!

87.

It won't actually hurt it, but it will make your transom more black. The higher octanes won't burn as completely on an engine designed to run 87. 87 will burn the most completely and make the most power.