flyrotary@lancaironline.net Mailing List Archive

Chris,

My manifold is stuck under the cowl mockup for at least another month and I do not have any pictures. Maybe Dennis can post a picture of his. He is using a swirl pipe and I am going to try a 180 deg bend to get the exhaust pointed in the needed direction. The muffler is cool but the exhaust manifold and pipe are very hot. We are both going to try the muffler inside the cowl with heat shielding and some air blowing over everything. Using a cut down stock manifold there is only one pipe and no collector

I have concerns about heat in the cowl after shutdown with this arrangement. We shall see.

Bobby

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of the mallorys
Sent: Friday, August 25, 2006 5:07 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Exhaust system

Bobby,

How long are your pipes before the muffler? Are either of you putting the muffler inside the cowling? If it runs that cool, it shouldn't be a problem.

Chris

----- Original Message -----

From: Bobby J. Hughes

To: Rotary motors in aircraft

Sent: Friday, August 25, 2006 4:08 PM

Subject: [FlyRotary] Exhaust system

Chris,

If I remember correctly you have a Renesis. After hearing Dennis's run-up to 5100 rpms last week I am planning to use the same muffler he has. Here are the specs he gave me.
Hushpower II

Flowmaster Performance Resonator

12512400

2.5 in. inlet/outlet

409 SS construction

This little muffler sounded much deeper and quieter than I expected. No level measurements but it was not unpleasant. We are both modifying the stock exhaust manifold but are trying two different methods of attaching the muffler to it. Will it hold up is another question.

Bobby

(engine still under sheetrock mud) :)

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of the mallorys
Sent: Friday, August 25, 2006 3:41 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Exhaust system

I've looked back through the archives, and seen lots of different ideas for exhaust systems. But no real definitive answers.

There is the Cool tube exhaust that has very short pipes,like Bob White posted.

There is the medium length, no muffler system like Buly has or like Joe Hull has mocked up.

There is the really long tubes with muffler hanging under belly like Tracy has.

Do we know what the correct length tube is to tune the exhaust for our RPMs? Does this length include the muffler?

It appears the diameter most used is from 1.5 to 2".

What about the different mufflers? I only found two mufflers named in the archive that guys are happy with, the Flowmaster Hushpower II, and the Moroso Spiral Flow Racing Mufflers. Last year at Shady Bend, Monti talked about noise levels and testing different mufflers and pipes. Are there ant results from that?

I'm ready to start mocking up my exhaust, so am seeking the collective wisdom of the group.

Chris

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