Quote:
Originally Posted by KingLT1
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The LT1 needs lower compression to run 93 octane with boost efficiently imo. This engine can not even reach MBT naturally aspirated on 93 which is why you see bolt-on cars pick up 25-30whp from E85 alone.
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There are two factors to this
1) depends on how much boost we are talking about
2) The NA cars make more power in part because of E85 at max rich power is just injecting FAR more working fluid available for expansion. M eth is even crazier...
Fuel .......................... AFR
Gas stoich ................. 14.7
Gas max power rich .... 12.5
Gas max power lean .... 13.23
E85 stoich .................. 9.765
E85 max power rich ..... 6.975
E85 max power lean .... 8.4687
E100 stoich ................. 9.0078
E100 max power rich .... 6.429
E100 max power lean ... 7.8
So even though 7 to 1 A/F is not really being "burned" efficiently, it is adding to the expansion of the charge during the combustion cycle. Think of it as a steam engine. I've done the math before in the N/A forum, I leave it to the youngons cause mole volume and atomic weight stuff is 1/2 century ago for me.
IMO 11.5 is near perfect at 7 PSI of boost and E85, built engine. For 8+ PSI, I think I would go on the safe side and do 10.5. This is IMO of course. Also remember a built engine is losing a huge amount of static compresion due to bleed off. My cranking compression is like 165 PSI with cam, vs say dunno 220 stock?
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Forged short block, large duration sub .600 lift Cam Motion cam, 7200 RPM fuel cut, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0 pump, ported front cats, 60608 Borla, LT4 injectors, ZL1 1LE driveshaft and Katech ported TB, ported MSD intake, BTR valvetrain, ARP studs, ProFlow valves, PS4 tires.