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Ignition Timing on different Ratios

Ethanol & Flex Fuel Tuning

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Discussion and questions related to the course Ethanol & Flex Fuel Tuning

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Will different (lower or higher) Ethanol % cause change in (Advance or Retard) Ignotion timing. i.e, Commercial E85 at 2500rpm has 30° Advance, changes to E56, would Ignition timing at 2500rpm will ignition more likely need to be advanced or retarded?

Hello Antonio,

It depends on your application, if the engine is knock limited then the higher ethanol content will allow you to advice the ignition and achieve MBT. If the engine is not knock limited then you may find that the ignition will be similar or retarded.

The relationship between ethanol % and ignition or MBT is not linear with the biggest gains been seen from E0 to E30 with E30 higher or having a less of an effect on Ignition and torque.

The flex fuel tuning course and webinar should cover what you need;



Hey Thanks Scott, Thanks for the response. I was in the middle of the course & that question popped in my mind & you answered it. Thanks alot!

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