Hi guys:

I´m needing some help with this one. I´m test benching this engine before install it on my Aerotech P-47 wich has already a Brison 4.2.

The decision to change engine was due the problem I´m having flying the airplane here in a real tropical weather, a lot of humidity and hig temps. When I compare my fligths from here and Florida, there is a huge difference, so after a lot of tunning testings and propeller changes the best is have some power to spare due the conclusion is the loss of power and performance from USA to here.

So, my 4.2 works fine with a Zinger 22x10 and better with a 3W 22x10 those props runs static around 6400. For some scale manouvers like victory roll,military roll, chandelle etc I need to keep speed, so here is when 4.2 tends to overheat at WOT, if I rich you can feel the lower rpm at WOT and also lower speed and weak manouvers.

After break in the 5.8 I installed the 22x10 just to have a reference and start to write down all information before to swap engines. I get 6800rpm at WOT, later I change to a 22x12 and get the same 6800, later I change to a 24x10 and same reading.

I could go further with test due a particular problem came out and this I believe is due the vibration problems, the throtle body butterfly get loose and scuff to the carburator body sides so it sticks when you idle. I change carb and took the one from 4.2 wich is the same and star over again the test and same damit problem happened so I had to stop and fix carbs wich I did already and post this article before going further.

I´m not very expertise with big gas engines for airplanes besides I work with outboard race engines, maybe I´m thinking wrong and I´m asking too much for this one, but if you dont aks you dont know.So guys, what is the max RPM suitable for this engine? Which is the best range were to keep runing and get the optimal performance for such engine.

Take in consideration I cannot go bigger than 24 or 25 due ground clearance.

Will a 3 or 4 blade propeller help with vibration at hig rpms? what gain what to loose.


Lets go guys, I´m here to learn from the experts and please get focus on the 5.8 and ask me more info if you need