Tuning on E85

[Sonic Blue 85]

I have a car that has about 12.1:1 cr., so I have desided to run it on E85. The fuel I got for the car has 85% ethanol, I did not know there was that much ethanol in E85, now I know where the name comes from. I called Dyno Jet to ask them about what air fuel ratio it optimum, they told me stoichiometric is between 9.6:1 to 9.8:1 depend on who you ask or exactly what mixture of ethanol you have. I started tuning the car today, so far it has been fairly easy, I think I have the car mostly tuned. At WOT I desided 8:1 A/F looked pretty good, 7:1 was definitely too rich, on the last run I leaned it out to about 8.2:1, it picked up 6 hp and 10 lb. of torque. 7:1 A/F put the power about 30 hp lower that it did at 8:1. My question is what have others found to be best A/F for WOT on E85? This car is natrualy asperated. Thanks in advance.

[Wallace]

What are you using to measure your AFR?

[bgjohnson]

Lambda is a better way to measure it unless you recalibrate a regular wideband sensor gauge to read the 9.76 Stoich.

[Sonic Blue 85]

I recalibrated the wide band for a stoichiometric of 9.6:1.

[Wallace]

I'm using e-85 and I just tune it like gasoline. I'm using the Innovate LM1 I don't think you have to change it since it's really just reading the o2 content should basically be the same target AFR for gas or e-85.

[bgjohnson]

Wallace is right. You do not have to recalibrate the sensor to reach stoich at 9.76. Basically your 14.7 on a uncalibrated gauge = 9.76. The sensor doesn't care what your burning.

[Sonic Blue 85]

Basicaly I talked to Dyno jet, I have a Dyno Jet dyno, they told me to go into the set up and create a new fuel type and then enter the stoichiometric A/F ratio, so I enter the info they gave me. So far none of you have answered my question, I am gessing none have any experiance with E85. I finnished tuning the car that I was working on. I stopped at 8.2:1 A/F at WOT on the last run last night the car seemed to like that best. Today the humidity is very high and it's raining, so I did not try making anymore pulls with the car today. I was just currious if any of you had any experiance with E85 and if so what A/F ratios have you found to work best at WOT, that was my question.

[Wallace]

right, sorry I can't help you but I didn't change my wideband to read like yours does so no idea what numbers you need. Good luck.

[Sonic Blue 85]

 Since stoichiometric for gasoline is 14.7:1 and with natrualy asperated cars optimum A/F at WOT is usualy around 12.5: to 13:1. So having been told that stoichiometric for E85 is 9.71:1, I gessed at around 8:1 A/F at WOT for E85. I found that richer than 8:1 was definitely too rich, the engine lost 30 hp compaired to what it did on gasoline. 8:1 seemed like it could be rich, but I ran out of time on tuning the car. I would have pulled the plugs and read them, but I am not sure about reading plugs from an engine running alcohal. All of the plugs I have pulled out of engines running alcohal in the past looked to me like they were running very lean. When I looked at the data logs of the runs I made, under light loads the factory O2s seem to read normaly, but under WOT they are reading rich, they were at .80, .84, .86 at WOT. Looking at the readings I got from the factory O2s, I would gess I should lean the engine out to 9 something to 1, possibly as lean as 9.76:1. Which has me woundering if the engine needs to be richer than stoichiometric at WOT when burning E85, like you do with gasoline?
 I am supposed to get the car back in a couple of weeks to continue on it. Before then I would like to get as much info on reading plugs for alcohal engines and any info I can find on tuning E85.

[bgjohnson]

I'd be surprised if there weren't a ton of threads on here about it. Like most, I can't tell you anything about the conversion between your gauge and gas.

I know guys that run around 11:0-11.8 on a gas set gauge. And E-85 can run a leaner cruise tune. Like i said, Lambda is easier for consistency.

Running rich on E85 isn't as bad as doing it on gas ( IE egt's, damaged valves/headers ). If you figure out the conversion

[LowBoostinT76]

Lamda x stoichiometric = afr

so if you want gasoline use 14.7 for the stoichiometric.

e85 stoichiometric of 9.8

This formula also applies in reverse.

Lamda = afr/stoichiometric

So lamda of .80 is
for gasoline 11.7
E85 is 7.8

I prefer to use gasoline number when I tune on e85 since when I am driving and go lean, my brain responds quicker to gas a/f ratios than ethanol.  Also using the gasoline numbers you have a broader spectrum of numbers, if that makes sense.

[65ShelbyClone]

So far none of you have answered my question........I stopped at 8.2:1 A/F at WOT on the last run last night the car seemed to like that best.

You answered your own question. Maximum power generally lands somewhere between lamda 0.8 and 0.9, which you found out yourself with 0.836.

[chad434sc]

I messed around with E85 this year with my car. I backed the timing off to be safe and started tuning on a Dynojet chassis dyno. I just kept my A/F around the same as my pump gas. I tuned it to around 11.5 and I made 781hp to the wheels through an auto. The problem was with my metering blocks the only way to get that much fuel was to open some stuff up huge and then it was to rich to drive on. I went back to pump gas with methanol injection. Made 731 to the wheels still with no timing in it. I am going back with E85 next year but with a different carb. I am still confused as to what I should be tuning it to. I also agree that you cant really go off of plug readings when on E85. No matter how rich it was the plugs looked so clean.

[underpsi68]

I  tune for a very safe 11.2:1 on a gasoline display WB.  Just tune for the same A/F as if you are using gasoline.  The dyno will tell where the motor likes to run.  Mine picked up 25RWP from 11.2 to 11.5.  i got scared and stopped there LOL.