My understanding is that ethanol in fuel makes the engine run leaner. I'm wondering what other's experiences have been, I'll share mine:
The engine in my UltraStar is the venerable Cuyuna ULII-02, with the original Mikuni carburetor. The sea level (where I fly) jetting reccomendations in the Cuyuna manual are 310 from 40°-60°, 300 from 60°-80°, 290 from 80°-100°, etc. When I got the plane the original 300 jet was in the carb, and the previous owner ran on avgas, as did I at first.
The only difficulty I had at first was excessively rich running at cruise on one day when it was about 90° and very humid... I dropped the needle one notch (clip now in the top groove) and that fixed it. When the weather got colder, I switched to the 310 jet and all was well (below 40° it's too cold to fly!).
Come spring, I switched to auto gas which around here has 10% ethanol. At temperatures into the 80's it still seemed fine with the 310 jet, though I moved the needle back to the second groove. EGT has always been around 1150° and plugs look OK.
The other day, with the temperature around 90°, it seemed a bit off, EGT closer to 1100°. I switched the jet to the 300 and noticed an immediate improvement, EGT back to around 1150°.
Thus it seems going from avgas to mogas with ethanol means about 1 jet increment. Come winter, when I'm flying less, I'll go back to avgas as it keeps better.
-Dana
Be Politically Incorrect: Support the Constitution!
The engine in my UltraStar is the venerable Cuyuna ULII-02, with the original Mikuni carburetor. The sea level (where I fly) jetting reccomendations in the Cuyuna manual are 310 from 40°-60°, 300 from 60°-80°, 290 from 80°-100°, etc. When I got the plane the original 300 jet was in the carb, and the previous owner ran on avgas, as did I at first.
The only difficulty I had at first was excessively rich running at cruise on one day when it was about 90° and very humid... I dropped the needle one notch (clip now in the top groove) and that fixed it. When the weather got colder, I switched to the 310 jet and all was well (below 40° it's too cold to fly!).
Come spring, I switched to auto gas which around here has 10% ethanol. At temperatures into the 80's it still seemed fine with the 310 jet, though I moved the needle back to the second groove. EGT has always been around 1150° and plugs look OK.
The other day, with the temperature around 90°, it seemed a bit off, EGT closer to 1100°. I switched the jet to the 300 and noticed an immediate improvement, EGT back to around 1150°.
Thus it seems going from avgas to mogas with ethanol means about 1 jet increment. Come winter, when I'm flying less, I'll go back to avgas as it keeps better.
-Dana
Be Politically Incorrect: Support the Constitution!