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If I use re -17cc pistons it gives me a compression ratio of 10.6 and dynamic of 8.9, doesn't this sound too high for 91 octane? Spoke with 440 source and they said majority if people go with the 17cc kit. I'm trying to find some definite information on running 91 with this setup before I dish out the cash. The -27 gives more conservative numbers, CR of 10:1 and dynamic of 8.4:1 but yet the 440 source tech said not many people order this, why? I understand leaving power on the table but I'd rather have it somewhat mild, good street manners and super reliable.

80cc stealth heads
Lunati 60312 hydraulic roller
440 source 512 kit



Since you big hang up is running on lower octane fuel just use the piston that gives the lower compression ratio ..



if he is all that concerned about compression
use the low compression piston... I said what I run
and that makes 590hp out of my 416 525 tq... if I
want to change the compression I can change head gaskets
but right now my quench is .040