RE: nitro & pipe length tuning
Mr Jensen,
The same engine/pipe setup cannot be used both for 10% and for 30% nitro!
30% nitro fuel will need a significantly lower compression ratio than 10%... Shimming the head up with 0.2-0.3 mm shims is the minimum effort proposition...
The exhaust gas temperature is different as well, making the tuned length for the pipe different, even for the same RPM...
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Choose your setup first and then tune and optimize the engine, prop, glow-plug and the exhaust length for that choice.
And you must understand that if you try using the other fuel, the setup will not work right!
'Unisex', or in other words, 'one size fits all', does not work in the real world of model engines.
And take another note; 30% nitro fuel is not only much more expensive per gallon. It is also used at a much higher rate than 10% nitro fuel, so your fuel costs will skyrocket if you choose the higher nitro.
It is unnecessary for anything but competition.