Gains from E85 (ethanol) on an N/A bolt on 370Z

jrb55gh

I filled my tank with a ~47% ethanol/ gasoline mix to see what would happen. I data logged a short time after the fill up with my ecutek software and noted the differences at full and part throttle.

The short term fuel trims increased 10-15%. Long term trims hadn’t moved yet. I guess they will after some more run time. So far there is no check engine light.

At part throttle the ethanol mix showed about the same afr for 93 octane, ~14.5. That indicates the ecu adjusted the fueling to maintain the O2 level in the exhaust to what it thought was stoich for straight 93 octane.

Full throttle showed ~12.5 afr. The normal full throttle afr for 93 octane with my tune is 11.97. That indicates the ecu followed the hard programmed fueling tables for full throttle operation. This is a quick way to lean your full throttle tune.

Ignition correction (because of knock detection?) was ~3 degrees was the same for both fuels. I am not sure if the retard was because of knock or a retard built into the ignition tables because of our 100 degree F. summer temps. I thought the extra ethanol would have increased the octane level of the fuel to prevent knock. Its time to google the octane levels of various ethanol gasoline mixes to get that answer.

Hard to tell about performance gain. Butt dyno says same or maybe slightly better response. If the ignition correction would go away, there should be a performance gain.

The E85 here is $1.59 and the 93 octane is $2.29. Looks like fuel mileage will be lower.

So far running 47% ethanol appears to be safe.

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