RE: How much nitro is too much
Hi Pete......
Run what ya have. Its not really worth going out of your way on more nitro, but if you have it, the engine will enjoy it.
Jett specs the engines at 15% nitro mainly because that is the most content many sport flyers use, and it is also the spec fuel we use for Q-500 and QM40 racing..... so we always have it on hand.
I've run my engines on heli fuel and 20/20, others have too. Same reason as you--- only felt like lugging one jug to the field. Not a big issue. Just set the engine down an extra 100-200 rpm off of peak rpm for launch. Nice thing is you will see a few more rpm in the first place, and get even more in the air. And the engine doesn't mind the extra oil either, just bring a few more paper towels for aircraft cleaning when you are done.
If anything, you may have to play with a couple of glow plugs to get the transition the best - but with a basic K&B 1-L plug you should be pretty much in the right place.
Too much nitro....... I'd say going over 30% is a waste of money - and that starts to get into that timing and compression stuff a bit more.
If for some reason one of the engines runs goofy or you are seeking to turn more prop, then get back to me and we can talk about a shim ---- but thats an isolated case.
Let me know how things go
Bob