Generally 10.0-10.5 compression will run on 92 no porblem. I ran 11.3 to 1 with iron heads and a zero deck and it loved 92, even on 95 degree days. CC designs such as the vortecs allow about an extra .8 of a point of compression on the same octane. A 38-45 quench will also help detination. Alum heads also allow an extra point or so compression and different cam grinds will bleed of compression at lower rpm's which basically means you only need to add a 92/ higher octane mix when you plan to race up in higher rpm ranges. |
