O.K.
Here goes.... I have always UPPED the nitro in my really worn oldies, though I don't have any long-hair sci-en-tif-ic study to back it up, they start easier. Can't claim a power increase,- like I said these are pretty whooped by this time. Most were abc, plain bearing, .25-.40 size. Ever ran a couple on 25% car fuel, and they went from almost ready to die to lively engines for several dozen more flights. I have only "broken" one engine, and it was a .19 Veco, and that was due to running LOWER nitro. It had been running on my standard mix of 15% with 4 oz. of castor, and 2 drops of Armor-all. We ran out, and a guy had some 0% in his car, so we filled it up with that, and though I can't give you a real sci-en-tif-ic explanation as to what happened, it broke the CONNECTING ROD right about in the middle. (too cool, started to seize, and fatigued the rod?)

Jetts