RCU Forums - View Single Post - MVVS 77 Prop Choice (no pipe)/FAI fuel consumption
Old 07-29-2015, 10:49 AM
  #1  
GoNavy
My Feedback: (15)
 
Join Date: Jan 2002
Location: Rib Lake, WI
Posts: 557
Likes: 0
Received 0 Likes on 0 Posts
Default MVVS 77 Prop Choice (no pipe)/FAI fuel consumption

I would appreciate your suggestions on prop choice and fuel consumption for the MVVS 77 running without a pipe (pitts muffler).

This is the old style (with separate prop shaft) but with the upgraded nozzle and idle needle (#s 0253 & 0232)

I will run FAI fuel, no nitro, and use the MVVS plug that came with the engine.

Instructions from the MVVS website (for the newer version of the 77) recommend 13 x 7, 13 x 9 or 14 x 7, and "min RpM 10,000"
noting that actual rpm's will vary with prop design and silencer used, and, they add
"Use lighter propellers with standard silencers so that the engine will be able to reach at least the Rpm listed above.)

I plan to use wooden props, not APCs.

I understand there is a significant drop in performance without a tuned exhaust, but if you have had experience with this engine, what size prop should I consider to achieve the 10K rpm on no nitro fuel?

Secondly, does the lack of nitro mean increased fuel consumption? Is the difference enough that I should go with a larger tank than I would use with 15% nitro?