convert

[tsrt]

new project to convert a yammie from gasoline to alcohol, need advise on timing, compression,jetting and so on

[zul8tr]

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 :cool: 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. :eek:

http://www.boatracingfacts.com/forums/showthread.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 :)