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Well guys I decided to switch to the darkside and try out ethanol in my basically stock LS2 C6. I do not have a flex fuel sensor installed so when filling up with ethanol i used the following to set the stoich afr: Tested pump ethanol to be exactly e85 with my test kit, took 13.5 gallons e85 which means there is 4.5 gallons premium 93 octane left in my 18 gallon tank. The stoich afr for this exact mix is 11.025. I uploaded the tune and started data logging then fired her up… immediately I noticed the ltft at idle -25 so I just let it idle a bit to burn off the 93 left in the fuel lines… held it at 2k rpm’s for a min then left off and reset the fuel trims. Seems I’m seeing about -8 on the ltft’s at idle but when i give it some throttle the ltft’s come back to around zero. The car seems quieter, the idle is smoother and it smells great with no cats. I threw in a degree of timing above 4k rpms and so far no serious knock retard (.3 deg)… will drive around a bit tonight and see what happens with the fuel trims, kr etc… i will test the ethanol content each time i fill up and calculate the stoich afr correctly but seems the ethanol is pretty consistent locally from other guys running it here. If I can add some timing in and no knock being detected i’ll be happy and purchase the sensor so I won’t have to manually calculate the stoich afr everytime I fill up. So yes you can run a stock ls2 on e85 with the stock injectors. My max injector duty cycle hit 95% with the 11.025 stoich afr, pure e85 next time will put me at around 9.8 or 9.7 stoich afr so I am maxing out the stock injectors. I’ll probably be needing a larger injector very soon… Figured I would share this info withe the group. Price at the pump 2.39 a gallon for the E but also have to factor in using 30% more fuel. Will report back with more findings!
Last edited by Corvettechris86; Sep 29, 2025 at 06:11 AM.
Well I did it and I’m able to run quite a bit more timing with zero knock retard. Car feels much much better but my injectors are about maxed out at 95% duty cycle.
I went with a flex fuel sensor + tune, but I went from 630hp on 91 to 690+ on e85. The extra octane certainly works, and, still comes out ahead in miles per dollar.
That is interesting to know! I put FIC 525 cc injectors IS301-0525H High-Z 58 lbs/hr @ OE 58 fuel pressure in mine for E85. The fuel pump is getting to low flow now.
I heard there is no sensor to actually determine fuel pressure at the rail on these cars? I will have to check to see if I can log it… As is right now it appears to be running rich 800-900 mv on the narrowband wot.
I heard there is no sensor to actually determine fuel pressure at the rail on these cars? I will have to check to see if I can log it… As is right now it appears to be running rich 800-900 mv on the narrowband wot.
Correct. You can log it, but it will just show 58psi simulated and not an actual pressure reading. You'll need an aftermarket pressure gauge/sending unit to check the actual fuel pressure.
I need to figure out how to enter injector data for hp tuners when I upgrade my injectors. On a side note the ect’s are nearly 20 degrees cooler on a 77 degree morning compared to normally running 205 degrees! I also went from seeing 18 degrees timing to around 24 degrees in the upper rpm range. I dont understand how it is seeing so much timing as in that range i have it set to 19 degrees in the high octane table. How does that work?!? The alcohol adder timing table is zero’d out from the factory too…
According to hp tuners I’ve picked up some nice gains down low… before est tq and after e85. I’ve read to copy the mbt spark table over to the high octane table when running e85 since it is possible to reach mbt on 100 plus octane ethanol . Can anyone confirm this?
I went with a flex fuel sensor + tune, but I went from 630hp on 91 to 690+ on e85. The extra octane certainly works, and, still comes out ahead in miles per dollar.
is that with boost? i cant imagine it gaining 60+ hp NA but that why i'm asking lol
Flex fuel sensor is plug and play, fuel side. Goes just before the fuel rail. Gets power from an injector harness, then a wire ran down to the ECU on one pin.
I ditched the boost a pump and added a DSXaux fuel pump - connects externally to the gas tank, activated when the switch sees 2psi
Added 95lb injectors and run full e85 with tons of head room on injectors and fueling.
I’m loving this e85 and so is my LS2 which benefits more due to higher compression ration (10.9:1). I keep throwing more timing in her and she keeps taking it without any retardation.
Keep in mind adding timing could even lower hp. Playing on a dyno I've had a engine not gain anything even after adding more than +5 in places. Each engine is different in what it likes (and at that snap shot in weather) but I have found E85 to allow the settings the engine wants (usually more timing than stock).
I’ve ran out of injector and need to upgrade! Found some 55lb 550cc direct fit ls2 injectors on eBay but there is no injector data to input for hp tuners. I need to figure out how to tune injectors with no data.
I’ve ran out of injector and need to upgrade! Found some 55lb 550cc direct fit ls2 injectors on eBay but there is no injector data to input for hp tuners. I need to figure out how to tune injectors with no data.
I would highly advise against this. Step 1 for tuning is using injectors with proper data published. This data is generated from various bench tests and would be extremely difficult to generate on your own.
I have 60lb injectors from Fuel Injector Connection which have published data and they work perfectly. I'm at 80% duty cycle with them at redline and am considering a flex fuel upgrade along with larger injectors.
1st time e85 in LS2
