Higher % ( 25% or more ) got more combusion = higher speed but more heat & less lube.. great for Mod or high power engines
Lower % ( 20% or below ) got more lube but less combusion, a little lesser heat and top speed .. great for stock type engines or runin
Just my opinion.. if you r using torondo ( no matter how much nitro ) ur engine required a lot of after run process .. if not .. the engine will get rust pretty easily ..
Besides Nitro % .. there should be some other factors that impact the performance and temp of the engine, like, glow plug, weather, no of shim placed between the heat sink etc .. One critical factor is Main needle setup - how rich / lean it is .. but higher % of nitro will increase combusion and heat thz 200% sure..
If u have a temp gun.. run ur engine with the same needle setting on 2 different nitro % .. then measure ur engine's temp, u will c the difference ..
U need to test them instead of trust ppl blowing around ( like me )