ORIGINAL: Switch_639
on my 91fx... i am not getting the rpm that i would like to get with a 13x8 prop... this is recommended prop... what would happen if I go to lower prop like a 12x8 or so? would it have too much revs? is it bad to under prop an engine but still tach below the max rpm of the manufacturer? I want to get closer to 15K rpm... I am using the stock muffler which came with the engine...
Hi,
You can run a 12x8 APC on a that engine no prob.
91FX + stock muffler + 15% nitro + 12x8 APC = 12k RPM
91FX + Jett muffler + 15% nitro + 12x8 APC = 12.6-7k RPM
The latter is my current setup. I like to go fast too.
I can add also that a 12x6 is underpropping the engine. The 12x6 makes a lot of noise with no performance gain.
Cheers.