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Jett SS/LX Muffler - Gold

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Old 02-19-2009, 09:40 AM
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tIANci
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Default Jett SS/LX Muffler - Gold

Hi ... I got the above mentioned muffler for my Rossi 53. On the stock muffler with Byron 5% synth, I was taching about 15,600 RPM. With this new muffler I am only getting about 15,750 RPM. Am I using the wrong prop because I do not see much difference at all. I have yet to test her out on other props. The engine does seem to spool up faster though. I am looking at using this in a sport plane.
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Old 02-19-2009, 11:13 AM
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Default RE: Jett SS/LX Muffler - Gold

If you have a gold LX muffler.... too much prop.

What prop are you using?

That muffler really needs to hit 17,000 rpm ground peak to begin to work well.

Minimum ground peak target would be about 16,500. Prop selection should has to exceed 16,500 by a good margin. Then back off 600-700 rpm from the peak for flight.
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Old 02-19-2009, 12:29 PM
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Default RE: Jett SS/LX Muffler - Gold

Bob ... I feel dumb ... the figures should read 17,500 on the stock banana pipe and 17,650 on the gold pipe! So that is all about I can get outta the Rossi huh? I did expect to get a fair amount more RPM with the gold pipe, not 2K more but maybe 500-750 would be nice.
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Old 02-24-2009, 02:11 AM
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Default RE: Jett SS/LX Muffler - Gold

Bob .. I am so blind ... was getting the 17,600 RPM on an APC 8.8 x 8.75. Hope you can assist ...
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Old 02-25-2009, 06:18 PM
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Default RE: Jett SS/LX Muffler - Gold

Gettign up over 17,600 on the 8.8x8.75 is pretty darn good. That is a lot of prop. And it about where the muffler wants to stabilize at most of the time.

The Jett 60LX typically runs in the 17,500-18,000 rpm range.

Remember - that is ground rpm. The engine will unload more in flight. Find the ground peak rpm, back off 600-700 rpm from that for flight.

The 53 runs out of "breathing room" in the crankcase - no way you would expect to see 19,000 out of it unless it was underpropped a bit.

What plane are you going to fly with this? Prop selection has to be matched to the airplane.

Bob

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Old 02-26-2009, 06:31 AM
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Default RE: Jett SS/LX Muffler - Gold

Thanks Bob ... it will go into a Viper 500 for the moment, just want to see how it goes. Then soon into something like a Kelly Racer if I can get the muffler to fit.
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