Prop for a MVVS 45cc engine
#7
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RE: Prop for a MVVS 45cc engine
The larger props are needed if you have noise limits. That also would prohibit the use of a pitts muffler.
The engine indeed tunes best if allowed to run at ~7000 rpm
The engine indeed tunes best if allowed to run at ~7000 rpm
#9
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RE: Prop for a MVVS 45cc engine
Jan,
Of course there is a best length. I have run a series of tests lately, that confuses you ad infinitum.
For the MVVS header I can tell you that 300mm is about the best for sub6000 rpm. our header seems a lot longer than that.
Thinner headers reduce power, but broaden the power peak
thicker headers shift power band up and narrow the peak
run a series of test using different props. This will show you the peak power rpm (use my prop power calculator, download from my web). Plot the curve, and you will know what to do!
Of course there is a best length. I have run a series of tests lately, that confuses you ad infinitum.
For the MVVS header I can tell you that 300mm is about the best for sub6000 rpm. our header seems a lot longer than that.
Thinner headers reduce power, but broaden the power peak
thicker headers shift power band up and narrow the peak
run a series of test using different props. This will show you the peak power rpm (use my prop power calculator, download from my web). Plot the curve, and you will know what to do!
#10
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RE: Prop for a MVVS 45cc engine
I'm a strong believer that more than half of the average flyers out there are twisting the wrong prop (s),, why are these guys revving their G38 at 8300 with a 18x10 in a 16, 17, 18 pound Biplane when a 20x6 turning around 7000 would be much much more efficient, and at 7000 the engine would not be over revving out of it's torque range,, same old story I guess
Jim
Jim
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RE: Prop for a MVVS 45cc engine
ORIGINAL: karolh
Try a 20x8 or 20x10.
Karol
Try a 20x8 or 20x10.
Karol
MVVS are a high performance engine.
Those props are way too small. My MVVS 35 turns a Menz 20 x 8 at 7000, so you'll need at least a 22 x 8 or even larger for the 45, which is a real powerhouse.
Great engines