E85 without a tune

[Soulja4187]

So a buddy of mine has a Camaro SS and after our cruise we had to get gas while we were there be put 4 gallons of E85 and the rest 93. I told him that unless he's not tune for it he wont see any perfomance and I dont think that's healthy for the engine. He said that he's been doing it for almost a year and hasnt notice any issues. What are your thoughts?

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[EFI]

I told him that unless he's not tune for it he wont see any perfomance and I dont think that's healthy for the engine.

Neither of those are really concern with this low of a blend. As you can see below, this is around a E30 blend.

Also, modern computers are much more powerful than earlier ones and can self adjust for both ethanol and power (up to a certain degree). Alot of GMs you see are marketed as flex fuel vehicles, my old Jeep Grand Cherokee was one also and they could handle up to a certain mix.

And on the power thing, the computer constantly monitors knock and adds or subtracts timing based on lack of such. For example, the Coyote computer can add or subtract up to 10* of timing from its base tables. If you put in higher octane fuel, and the computer doesn't see knock, it will keep adding timing over base and thus you could see more power. It's not as good as a real flex fuel tune which adds timing more aggressively, but it's not completely useless.

 

[Soulja4187]

Neither of those are really concern with this low of a blend. As you can see below, this is around a E30 blend.

Also, modern computers are much more powerful than earlier ones and can self adjust for both ethanol and power (up to a certain degree). Alot of GMs you see are marketed as flex fuel vehicles, my old Jeep Grand Cherokee was one also and they could handle up to a certain mix.

And on the power thing, the computer constantly monitors knock and adds or subtracts timing based on lack of such. For example, the Coyote computer can add or subtract up to 10* of timing from its base tables. If you put in higher octane fuel, and the computer doesn't see knock, it will keep adding timing over base and thus you could see more power. It's not as good as a real flex fuel tune which adds timing more aggressively, but it's not completely useless.

So what performance or advantages do you get in putting so low E85? Well besides gas not lasting as normal when just using 93

 

[Matthewstorm]

So, are you guys saying I can run E85 on my 2021 with no tune or additional hardware?

 

[Soulja4187]

So, are you guys saying I can run E85 on my 2021 with no tune or additional hardware?

Yes and no, you can only run diluted E85, like 3 to 4 gallons of it and the rest has to be 91 or 93.
Never fill completely with E85 unless you are tuned as your injectors aren't set up to push enough to have the car running well.

 

[EFI]

So what performance or advantages do you get in putting so low E85? Well besides gas not lasting as normal when just using 93

Not much really, but it's still better than pure 93 octane gas.

95 octane offers a little bit better knock protection, so even if you're not gaining power it's going to be more stable. and safer Also a little bit of ethanol helps keeps the cylinder charge temps cooler so again better knock resistance. For say an endurance race or for a drag car that does long highway pulls this blend would help quite a bit over pure E0 93.

 

[EFI]

So, are you guys saying I can run E85 on my 2021 with no tune or additional hardware?

Pure E85 no!

But you can mix in a little bit of E85 up to a certain degree bad be ok.

 

[Zelek]

I hope you guys are monitoring your fuel trims when you do this.

 

[Matthewstorm]

I hope you guys are monitoring your fuel trims when you do this.

How would you do that?

 

[Soulja4187]

Today I will put 4 gallons of E85 and the rest 93. Will report back on how it runs, one thing that my buddy said that when he runs the mix he runs through the gas like nothing is that true?

 

[Copperhead73]

The folks above probably understand this a lot better than me, but I wanted to explain what is going on a little more thoroughly to help you reason your way through this.

The main thing you are getting with E85 from a performance standpoint is pre-detonation resistance, meaning you can run more timing. You have to burn more alcohol to make the same power as gas. This is why your fuel mileage is shit on alcohol. As the percentage of your mix that is alcohol rises, the fueling system has to supply a larger volume of fuel to the engine. At some point, your stock fuel system cannot deliver enough alcohol to make good power and so while you may be able to run more timing, the "boom" just isn't as big as it would be with more gasoline.
If your fuel system can deliver enough fuel to make E85 effective, you still need a tune to get the aggressive timing to make any additional power.

I am probably oversimplifying here. I suspect that as others have said, if you mix a little E85 with 93 Gas, you are getting a higher octane final mix that the factory timing parms can get a little benefit from in terms of power. The ratio is gas-rich enough that your fuel system can supply enough of it to work. I am spit-balling, but maybe you can get 5-10hp out of a stock Coyote? You def won't get as far on a tank of mix, if that matters at all.

I have no idea on the Eco 4. I would be a little leery of trying anything without a tune on the 4cyl because boost changes everything. It may work great, or burn a cylinder.

With the Coyote's (3rd gen, at least)...the stock fuel system can deliver enough volume on pure E85 to make good power if you have a tune to tell it to do so, and to give you the timing you need to make it worthwhile. I believe 2nd gen can deliver enough fuel with a tune, too, as long as there aren't any other engine mods such as intake or cams, etc. Those mods cause the engine to get more air, and with more air you need more fuel not to go lean. Basically the fuel system is already at the limit with the stock amount of air intake the motor is capable of.

 

[Dfeeds]

If any of the e85 pumps are like the ones by me then that "e85" can really be anywhere from e50 to e85.

 

[Matthewstorm]

Today I will put 4 gallons of E85 and the rest 93. Will report back on how it runs, one thing that my buddy said that when he runs the mix he runs through the gas like nothing is that true?

Yes.

 

[Copperhead73]

Today I will put 4 gallons of E85 and the rest 93. Will report back on how it runs, one thing that my buddy said that when he runs the mix he runs through the gas like nothing is that true?

Yes, because as I said earlier, you have to burn a 3rd more E85 to make the same amount of "boom" as gas. You get about 2/3rd as far on E85 as Gas. Whatever the percentage of your tank is E85 is, that percentage only goes 2/3rds as far. so if 5 of your 15 gallons is E85, your getting something like 15% less for your distance per tank.

 

[Soulja4187]

If any of the e85 pumps are like the ones by me then that "e85" can really be anywhere from e50 to e85.

Well there are 2 gas station that my buddy uses that have tested with high E85 in the ball part of 80 to 84%. I also found an Orion gas station that has E90 which states that its 90% Ethanol. I would love to try it out but once I'm tuned. I'm waiting for my 2021 GT to come.

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