Writing tune with SCT PRP for 10% ethanol fuel?

[Chris B.]

Almost all of the gas stations in PA and NJ, the two states I drive in the most, use 10% ethanol gasoline. I have the SCT pro racer package and I was considering making a tune for 10% ethanol gasoline. Most of what I read about 10% ethanol pump gas says that the for E10 the stoichiometric air:fuel ratio is 14:1. Also, to get the most power at WOT, I assume I should program it to run a bit richer than I would with 100% gasoline.

The things I was wondering about were:

Pump gas definitely doesn't have the quality control that race gas does, so is it even worth it to bother with the time to create a 10% ethanol tune?

What air/fuel ratio should I aim for at WOT with 10% Ethanol?

Is there anything else I should change in the tune for 10% ethanol gasoline?

Since pump gas doesn't have the quality control of race gas, if I got a tank of 7% ethanol or 9% ethanol, would it affect the tune much? I wouldn't be adjusting the timing more than a few degrees more than I would with 100% gasoline. If there is a little knock, wouldn't the PCM adjust for this?

Searching, I found many threads about E85, but not much about the E10 that many parts of the country are cursed with.

 

[one eyed willy]

here in florida , every gas station says it has "up to 10%".....my tune has never been adjusted for this.

 

[Chris B.]

With a forced induction car it would make sense not to adjust for 10% Ethanol gasoline because the ethanol helps reduce cylinder temps and reduce the chance of detonation.

 

[stang06gt]

Its the whole country man. Government fuel mandates have forced pretty much every gas station to use e10. So I would imagine it was already tuned running on e10 if bama tuned it.

 

[BruceH]

Set the stoich for 14.1 and keep everything else the same. Widebands are going to give you a reading of 14.64 for 1 lambda. By changing the stoich to 14.1 you are effectively telling the computer that is the new lambda. Look for the same wideband readings as with gas.

 

[lito]

With a forced induction car it would make sense not to adjust for 10% Ethanol gasoline because the ethanol helps reduce cylinder temps and reduce the chance of detonation.

Not true.

 

[Chris B.]

Not true.

What exactly isn't true? Ethanol mixed with gasoline helps reduce cylinder temperatures or that it reduced the chance of detonation?

 

[rford426]

What exactly isn't true? Ethanol mixed with gasoline helps reduce cylinder temperatures or that it reduced the chance of detonation?

Prolly about adjusting it in the tune

 

[Swarzkopf]

What exactly isn't true? Ethanol mixed with gasoline helps reduce cylinder temperatures or that it reduced the chance of detonation?

Eh...I'll try to answer as best as I can...

Ethanol's big advantages come from:
- Running a high percentage ethanol blend as your primary fuel and tuning for it. The increased volume of fuel being injected into your cylinders cools the combustion chamber and eliminates lots of knock, allowing you more timing/boost/compression/waddever.
- Injecting ethanol into the intake stream separately on a forced induction vehicle to cool the charge, though methanol has proven to be better for this.

Remember, the advantages from running alcohol come only after you tune your AFR for it. Without tuning for it, it has no benefit and is actually detrimental if anything. And honestly, even with tuning I can't see E10 having any real benefit- E85 is awesome, and I think guys have had great results with E70, but E10 just isn't enough ethanol content to provide a real cooling advantage.

 

[lito]

What exactly isn't true? Ethanol mixed with gasoline helps reduce cylinder temperatures or that it reduced the chance of detonation?

Basically, the not adjusting part, if you tune a car with pure gas and use pure gas stoich, then using E10 without adjusting the tune will make you run leaner, depends on what the tuner set as commanded lambda it could get too lean. If commanded and obtained and AFR(gas) of 11.8, you will end with well over 12 (about 12.2 AFR(gas) or 0.840 lambda)

If you were tuned already with E10, then no trouble at all.

 

[Chris B.]

Basically, the not adjusting part, if you tune a car with pure gas and use pure gas stoich, then using E10 without adjusting the tune will make you run leaner, depends on what the tuner set as commanded lambda it could get too lean. If commanded and obtained and AFR(gas) of 11.8, you will end with well over 12 (about 12.2 AFR(gas) or 0.840 lambda)

If you were tuned already with E10, then no trouble at all.

Most of the forced induction tunes I've seen were so rich already(to be safe) that I assumed that they would be more appropriate for 10% ethanol gasoline already.

 

[Chris B.]

Its the whole country man. Government fuel mandates have forced pretty much every gas station to use e10. So I would imagine it was already tuned running on e10 if bama tuned it.

I have to change my sig. I'm no longer running the Bama tune and running my own tune.

 

[05yellowgt]

There won't really be any extra power to be had with e10 fuel. The ethanol replaced the mtbe additives that the EPA deemed to be harmful. The mtbe was used to improve emissions and ethanol is now being used as a replacement. The downside of ethanol is the lower stoich and therefore reduced mileage since mtbe is very close to the stoich of pure gasoline.

The ethanol content of e10 is no where near enough in volume to have a significant impact on the temperatures inside the combustion chamber to allow increased timing and more power. Ethanol actually isn't very high on the octane scale but its ability to evaporate and reduce the temps in the combustion chamber allow it to deliver the same net power as a much higher octane fuel. E85 can deliver greater power on average than c16, again not because the octane is higher, but because the large volume of ethanol introduced into the combustion chamber cooling the air fuel charge much more than c16.

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[908ssp]

I think there is some misunderstandings out there. I don't much feel like taking the time to lecture. But if you're interested the BTU the amount of energy contained in a volume of gas is greater for 89 octane than 93 octane and even less in ethanol. Octane is the ability of the gas to resist detonation and there is less power in 93 than 89 per gallon. The advantage is you can run 93 in higher compression engines with more timing and that more than makes up for the loss in energy of the gas. Same goes for ethanol more timing, more compression and a lot more fuel means ethanol can make more power.

 

[05yellowgt]

For this discussion the BTU value is going to be related more to the mileage you will see with a given fuel than the power potential. Methanol has a very low BTU value but will make more power than just about anything that you can run in an internal combustion engine.

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[908ssp]

For this discussion the BTU value is going to be related more to the mileage you will see with a given fuel than the power potential. Methanol has a very low BTU value but will make more power than just about anything that you can run in an internal combustion engine.

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Right just what I said. I just made mention because some of the posts above give the impression the fuel makes more power which isn't exactly true. The engine makes more power with a given fuel only if it is designed to take advantage of that fuels ability to resist pre ignition.

 

[one eyed willy]

good info! So I run a 50/50 mix of methanol @ 8 PSI......does the 10% ethanol actually provide any pros? or is 10% too small of a dose?

 

[908ssp]

good info! So I run a 50/50 mix of methanol @ 8 PSI......does the 10% ethanol actually provide any pros? or is 10% too small of a dose?

If the engine tune can be altered to take advantage of the fuel then yes if not then no.