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Ethanol ignition advance

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Hello everyone,

I'm tuning a naturally aspirated motorcycle engine on ethanol E100 and my ignition advance is about 44° without reach the mbt, I know these engine runs about 50° of ignition advance stock on pump gas. Is it normal if my mbt exceeds that 50°, considering the fact that ethanol flame speed is faster than gasoline?

I'm afraid I'm having trouble reading torque

Here some engine specs:

Bore x Stroke: 89 x 60mm

CR: 12,8 : 1

How much load do you have when looking for MBT? Full throttle, lowest throttle (minimum MAP) at a fixed RPM, somewhere in between?

Finally, are you sure the commanded timing is the actual timing? (have you verified with a timing light?) -- I know this can be difficult on motorcycle engines.

Full throttle (about 91kPa), and yes, I checked with timing light it was ok.

How do you know you haven't reached MBT if you said you are having trouble reading torque? Can you do a torque optimization test similar to Andre's video?

I don't tune many bike engines however you're right that it is common for them to run ignition timing much more advanced than a car engine. While the factory advance for pump gas may be 50 degrees, that doesn't necessarily mean that was MBT. Ultimately you need to give the engine what it wants, providing of course you're not causing knock which I'd say on E100 with 12.8:1 CR would be impossible. Finding MBT however will rely on the accuracy and sensitivity of your dyno too.

Thanks Andre!

Raymond,tuning up to 44 degrees advance my reading was good, with the torque rising, after that my load cell presented some problems.

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