vegasjbug

My Feedback: (69)

Hi Bax,
I have the O.S. 1.60 FX mounted in GB 77" Yak 54. Engine has Perry Pump and all adjustments seem to be fine. Has about a gallon of run time on the stand. Turning a APC 19X8 at 7200 rpm with Pitts style muffler, good smoke and oil left on the concrete. Idle is 1750 rpm. Fuel being used is 20-20. Will this hurt the engine? I will not be doing full blown 3D, just sport flying with the other stunts....stall turn, inverted/upright spins....etc. I just want to get the most power I can for this size plane without toasting it.
Thanks,
Roy

T28RON

My Feedback: (32)

Roy: You are over proped. Try the 17 X 10 or the 18 X 10. start with the 17 X 10 and you will see a significant change in RPM. I think you are causing the engine to overwork with the type of plane you are pulling. The fuel you are using is fine. The O.S. recommendations are: Fuel with 18% (minimum) lubricant content and 5% to 25% Nitromethane (Can be flown on FAI fuel, which is 0% Nitro). However (Can be flown on FAI fuel, which is 0% Nitro). Hope this helps.


Ron

Bax

My Feedback: (11)

We'd say that you have your engine over-propped a bit. We prop it to run in the mid to high-8,000's. An APC 16 x 10 will turn in that range. We might use a 17 x 8 or 9, but your 19-inch prop's likely a bit too big.

sedrick

I am running a 160 on the GB 330L and have found that the APC 18X6 W give the best overall performance, much better than an 18X6 Zinger or masterairscrew prop. I am getting about 7900 to 7800 RPM but then richen the engine a bit as it is quite unforgiving of running hot