I am going from 65.5 cc head chamber volume to 61cc. how much should this add to my compression ratio - I have a 351w .030 over
(93 lightning) the motor has 2000 miles on stock rebuild. It has a 6 psi ford motorsports supercharger (powerdyne) I have a new set of trick flow twisted wedge heads (61cc) that i want to installwould this increase my compression too much for the supercharger? I was told the
original gt40 heads have 65.5cc ( but i dont know for sure?) any answers or advice would be greatly appreciated Thanks jeff moon (my compression ratio right now should be around 8.8? right now)

 

Weiands tech manual on supercharging states you need to keep your "effective" compression ratio at 12:1 or below when running pump gas (92 Octane). According to their charts 8.5:1 compression and 6 pounds boost equals 12.0 effective compression...the maximum you should be running.
Your guess-timated 9.3 compression with 6 pounds boost will equal 13:1 effective compression. I'd say you'll have to run some sort of boost retard timing control to control detonation...Deen