E85 Timing advice, E85 experts in please!
06-01-2011, 06:29 PM
#1
E85 Timing advice, E85 experts in please! I plan on paying for a short dyno session to dial it in, but I only get 3 pulls, so I want to get it as close as possible to optimal before getting on the dyno. Here is the engine info:
E.B. Porting ported stock heads 190cc intake, 52cc chambers.
Stock LT1 350ci shortblock with 11.7 Static compression, 9.3 Dynamic compression, Redline: 6450 RPM.
Custom cam: .582/.582 valve lift, 226/226 duration @.050 (277/277 @.006), LSA 110
Timing @.050: Intake: Open 5*/Close 41* Exhaust: Open 45*/Close 1*
Degreed Intake lobe to 108*
What do you pros suggest for WOT timing for this setup on E85? Here is my current extended spark table (which I think is probably a little conservative)
E.B. Porting ported stock heads 190cc intake, 52cc chambers.
Stock LT1 350ci shortblock with 11.7 Static compression, 9.3 Dynamic compression, Redline: 6450 RPM.
Custom cam: .582/.582 valve lift, 226/226 duration @.050 (277/277 @.006), LSA 110
Timing @.050: Intake: Open 5*/Close 41* Exhaust: Open 45*/Close 1*
Degreed Intake lobe to 108*
What do you pros suggest for WOT timing for this setup on E85? Here is my current extended spark table (which I think is probably a little conservative)
06-02-2011, 02:31 AM
#2
First off read the plugs!
Secondly you can add timing after peak TQ incrementally with RPM. The stock curve falls off at higher RPM so everyone keeps that downward slope, but really it should slope upward as cylinder pressure is falling the entire time engine speed is rising after peak tq, and more advance can be used... try it you will like the results.
Third, while I agree that it is conservative, I would reshape the latter end of the curve and arrive at somewhere around 38 deg max total timing, then READ YOUR PLUGS.
If your tuning off of a wideband for AFR, you dont even have to chop the threads off or buy an otoscope. Just read the timing mark on the ground strap.
Secondly you can add timing after peak TQ incrementally with RPM. The stock curve falls off at higher RPM so everyone keeps that downward slope, but really it should slope upward as cylinder pressure is falling the entire time engine speed is rising after peak tq, and more advance can be used... try it you will like the results.
Third, while I agree that it is conservative, I would reshape the latter end of the curve and arrive at somewhere around 38 deg max total timing, then READ YOUR PLUGS.
If your tuning off of a wideband for AFR, you dont even have to chop the threads off or buy an otoscope. Just read the timing mark on the ground strap.
