Hi guys,
I have a .91 FX mounted on my Extra 330S airplane, and was wondering what the ideal prop would be for this engine ? I used 14x6 for a few flights, but some people said that this could be too much for this engine. I am using Bisson pitts stlye muffler and the engine is cowled. I was being recommended to use a 13x8, so before making the switch, i thought to ask everyone here.
Thanks for sharing !
-Gaurav
Seems to be fine.
From Towerhobbies on 91FX:
Prop Size RPM
13x6 12,500
13x8 10,400 using a 13x8 prop,
13x10 9,500 Hobby Services tached this
14x6 10,900 engine at 11,300 RPM
14x8 9,500 6-24-99
14x10 8,400
15x6 10,200
15x8 8,100
16x6 8,30
Gaurav,
You need to judge yourself whether the prop performed as intended, if not then you can experiment and see what you like.
A 14x6 is in the middle of recommended size and hence should neither be underloading nor overloading the engine.