I live in Utah and fly through the Rocky Mountains on most cross country flights. I typically cruise at 10,500 or 11,500 (when I eventually get there), and in the summer the density altitude at cruise is around 13,000.
The performance of this little engine is impressive at altitude, but it does have its quirks.
I have noticed a peculiarity when flying at high altitude with automotive fuel, particularly ethanol fuels. When I fly with automotive fuel, I always have a fuel smell in the cockpit, which I have determined is coming from fuel venting out of the carb bowls. When I fly with 100LL, I do not have this problem.
On another note, I tend to run very rich at altitude. Regardless of the fuel type, my EGTs at cruise are around 1,100 degrees. Everyone I've talked to says to not mess with the stock jets, 1.5 turn on the idle jet, and needle clip positions. Given that my home field is at over 4,000 feet, I've questioned this advice but I've stuck to it. I have also accepted the advice to avoid the temptation of installing the HACman mixture control.
I've had occasion to run the Rotax near sea level twice. The performance and smoothness of the engine is awesome at lower altitudes.
If anyone has any insight into running the Rotax at high altitude, I would appreciate your wisdom.
The performance of this little engine is impressive at altitude, but it does have its quirks.
I have noticed a peculiarity when flying at high altitude with automotive fuel, particularly ethanol fuels. When I fly with automotive fuel, I always have a fuel smell in the cockpit, which I have determined is coming from fuel venting out of the carb bowls. When I fly with 100LL, I do not have this problem.
On another note, I tend to run very rich at altitude. Regardless of the fuel type, my EGTs at cruise are around 1,100 degrees. Everyone I've talked to says to not mess with the stock jets, 1.5 turn on the idle jet, and needle clip positions. Given that my home field is at over 4,000 feet, I've questioned this advice but I've stuck to it. I have also accepted the advice to avoid the temptation of installing the HACman mixture control.
I've had occasion to run the Rotax near sea level twice. The performance and smoothness of the engine is awesome at lower altitudes.
If anyone has any insight into running the Rotax at high altitude, I would appreciate your wisdom.