Your engine head is shimmed to run 15-33% nitro, even running 30% in trx motors will 'cause overheating issues. When I ran 33% Byrons Gen 2, which is just about the best fuel you can buy in my 3.3, no amount of richening of the HSN would bring the temps below 280F, it would haul ass, but once ran for about half tank, the temps would just keep climbing, I'd have to richen it to the point where it wouldn't even shift into 2nd it was gargling so much. In theory you can run 50%, but you would need some major shimming of your head to lower compression, maybe 2 or 3 of the thickest traxxas shims all together. I don't know where you got 50%, never heard of it, 35% from trinity is highest I've ever seen, and 40% for airplane stuff, is it actually car fuel?