Thread: AFR and E85
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Old 09-12-2013, 11:53 AM   #7
Element Tuning
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With E85 there really is no one right AFR to run as it works in a huge range unlike regular fuel. Add on top of that Direct Injection and it will really mess with your head. If you are reading in gas AFR 17:1-10 which is a much larger range then fuel which is about 15:1 to 10.

You will often run as rich as you can without misfiring for maximum power with boost since adding timing and boost far outweighs the gains you would get from leaning out .5 AFR.

The OEM ecu strategy relies heavily on the port injectors at high RPM so you end up with traditional AFRS while tuning 11.5-12.5 AFR but with the Hydra EMS we have more control on the ratio of direct injection to port injection and I was making the most power with AFRs reading off the chart lean. It wasn't actually lean however ..I know confusing
A very rough novice guide is to just add +1 to your gas AFR so if you cruise at 14.7 on fuel you can run 15.7 on E85 and if you tuned your car to 11.0 on gas you can run 12.0 on E85.

If you're a pro forget all that and just run as lean as you can get away with under cruise and whatever makes the most power under full load

Thanks,
Phil Grabow
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