Which will run longer on a small four stroke turning a largish, high-pitch prop at mid-range rpm? I have been using 15%, Should I try higher or lower nitro content to stretch my flight times? Need advice. Thanks in advance for your input. Tim[8D]

Tim:

Nitromethane is an additive to allow you to burn more fuel in a given time. Since duration by definition wants the slowest fuel rate possible, zero percent nitromethane is best, if your engine will run satisfactorily with it. And if it wont use a different engine.

Bill.

For even longer duration you can add a small amount of gas to your fuel, try 5% first. Also don't forget to add oil to keep the oil percentage up.