new project to convert a yammie from gasoline to alcohol, need advise on timing, compression,jetting and so on
new project to convert a yammie from gasoline to alcohol, need advise on timing, compression,jetting and so on
No specifics but here are general items to consider:
What type alcohol are you planning: methanol M, ethanol E, isopropanol I?
Converting to alcohol requires a larger fuel jet. For pure alcohol engines converted from gasoline the jet may need to be about 2x the area of the gasoline equivelant. Better to start too large a jet than to small or lean.
Alcohol burns much cooler than gasoline. M has the highest cooling effect, than E than I with gasoline the lowest. This effect allows for a denser charge to the cylindere thus potentially more power from this effect even though alcohol has lower BTU/lb than gasoline with I best, E next than M the lowest BTU/lb. Increasing compression will further increase the power output. Not sure of what the upper limit on compression ratio would be.
Alcohol has a slower flame speed than gasoline therefore more spark advance is generally needed -careful here as too much is bad for the pistons.
http://www.boatracingfacts.com/forum...ead.php?t=5472
A colder spark plug is generally needed. Testing is required to determine the best plug for the use.
Alcohol has greater anti knock properties than gasoline. M (rich setting) best, than E than I.
Start with a cold plug and rich jetting and back into the best jetting and plug.
Need some Yama guys to provide specifics
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