Fuel Economy and Power Generation of E30 Fuel

[mooferz]

Recently while trying to justify the butt-dyno feel that my Lexus is slightly faster with Ethanol in the tank, I found this corn industry paper regarding 94 octane E30 being produced from blending pumps in South Dakota, running in non-flex-fuel vehicles.
I don't think this has been discussed on BITOG yet:

http://www.sdfu.org/assets/docs/uploads/gle-e30-challenge-white-paper-1-19-17final.pdf

Really this is just evidence of how modern knock-controlled ECUs of today's high compression engines can take advantage of higher octane fuels.

I've been blending my own E20-E35 with 93 gas (up to maybe 97 octane) for the last year and a half, and though fuel economy suffers, it really is noticeably faster when you put a few gallons of e85 in the tank.
(Maybe this could be a sign I should replace the knock sensors.

)

 

[CT8]

Originally Posted By: mooferz
Recently while trying to justify the butt-dyno feel that my Lexus is slightly faster with Ethanol in the tank, I found this corn industry paper regarding 94 octane E30 being produced from blending pumps in South Dakota, running in non-flex-fuel vehicles.
I don't think this has been discussed on BITOG yet:

http://www.sdfu.org/assets/docs/uploads/gle-e30-challenge-white-paper-1-19-17final.pdf

Really this is just evidence of how modern knock-controlled ECUs of today's high compression engines can take advantage of higher octane fuels.

I've been blending my own E20-E35 with 93 gas (up to maybe 97 octane) for the last year and a half, and though fuel economy suffers, it really is noticeably faster when you put a few gallons of e85 in the tank.
(Maybe this could be a sign I should replace the knock sensors.

)
That is what I would have guessed.

 

[L_Sludger]

Originally Posted By: mooferz

(Maybe this could be a sign I should replace the knock sensors.

)

This makes no sense to me. If your car runs better with more knock resistant fuel, that is an indication that the knock sensors are doing their job.

 

[Seventh]

The thing to watch out for with homebrewing ethanol blends in non flex fuel vehicles, is that if you get too much of it in the mix you can cause fuel trim (aka air/fuel mixture) faults stored when the ecu thinks it's running too lean.

Ethanol has roughly 30% less thermal energy than pure gasoline. Meaning you have to inject 30% more to achieve the same power output. When you first add it to the tank your ecu will see lean mixture readings at the 02 sensors and add more fuel until the reading is stoich. This is why fuel mileage is decreased with ethanol usage.

Most ecus will only tolerate fuel trim deviations up to roughly +/- 10%, once that predetermined limit is reached the check engine light will be tripped because the ecu thinks there is a problem.

But more power, yes indeed. I have my subaru converted to run e85 or 91 octane, just have to flash the ecu real quick at the pump to switch from one to another. On the dyno my car puts down 60 additional horsepower and 80 more ft/lbs of torque at the wheels on e85. Same boost level, only a MUCH more aggressive timing curve.

 

[mooferz]

Originally Posted By: L_Sludger
Originally Posted By: mooferz

(Maybe this could be a sign I should replace the knock sensors.

)

This makes no sense to me. If your car runs better with more knock resistant fuel, that is an indication that the knock sensors are doing their job.

This was more a jest on how the 1MZ ECU is notoriously oversensitive in how it reacts to knock sensors.

You're probably right about this reasoning, this is just a sign that it's doing its job. Compared to 93, running the car on 87 feels as slow as 97-octane E35 feels fast.

Quote:
Most ecus will only tolerate fuel trim deviations up to roughly +/- 10%, once that predetermined limit is reached the check engine light will be tripped because the ecu thinks there is a problem.

This is mentioned in the paper, which the graphic implying that a check engine light is generated at +/-20% fuel trims, and this range seems to be the case with Toyota ECUs. I won't go more than ~+10% with my blends, for fear that this will kill my fuel pump faster, as OEM Denso fuel pumps are known for being especially intolerant of higher ethanol percentages than maybe 45%.

 

[Olas]

The car is NOT faster with ethanol, it performs closer to its efficiency window.

What happens is the car goes slower on normal fuel, and performance increases with octane.


Next time round, add a gallon of toluene or benzene or xylene to a tank of E0 87 octane and 'feel' for the difference