Ok heres what i have going.. I haven't bought pistons yet.. And getting the heads flowed next month.. Now here is what i have come up with for Compression ratio and DCR soo far.. I am pretty sure my heads are 53cc's.. Also having them check as well.

Right now with Mahle pistons -5cc my SCR is 11.93 and DCR is 8.84

What do ya think.. With a good tune could it run on 91? Or am i crazy.. It won't be an everyday driver, but it will get driven alot on the street and to and from the track every other weekend..

Heres a run down:
Mahle pistons -5cc ( haven't bought yet )
5.7 rods
3.480 stroke
4.125 head gasket bore
.039 head gasket thickness
0 deck ( haven't decked it yet )
4.030 bore
CC 306
290/307 adv. dur.
112 LSA
IC 108
Seat timing Open Closed
Intake 37 BTDC 73 ABDC
Exhaust 89.5 BBDC 37.5 ATDC

 

Why the 4.125" head gasket for the 4.030" bore?

The DCR is really pushing it for 91 IMO. You might consider a thicker head gasket although it won't help quench.

 

it's hard to say, so before I venture a WAG, why 91 octane? Is that the best you can get in your area?

Rich

 

Rich,
Yeah. I wish i was still back in Illinois.. We had 93 back there..
91 is the best i can find out here in AZ..

 

I've had a pair of Fel-pro 1074's laying around and was just going to use those..

I don't really want to run a thicker gasket either. I want my quench under .040

Best i can hope for is when i get my heads CC'd, that they come back bigger than what i think they are.. 54 or 55 would make me happy..

 

I think it will work but will be marginal. You mention you are in AZ - one important variable is altiude. Higher is better, at least as far as octane requirement is concerned. Other things include temperature, tune, and rpm range. The worst conditions would be a hot motor, high air temps, and WOT at low rpm with lots of advance. Stay away from thiose conditions if you want to avoid detonation. Also, run a plug a bit colder than stock.

Rich

 

Altiude here is 3300 feet.. It does get pretty hot here during the summer. Hot air temps. Thanks for all the pointers Rich, and i plan on running TR6's..

I'll know more once i figure out what my head CC's are..
Thanks guys!

 

I agree that you are pushing things for 91 octane. I see you have not bought your pistons yet. Maybe buy some with more cc? I'm running 8.5:1 DCR with my L98 on 91 octane and .035 quench.