Engine basics > Engine set up tips

Carbon Fiber RE header muffler

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Walter Hicks:
I noticed a picture of a Skywriter with a PA or RO Jett Re and a short header pipe with a Carbon Fiber Re muffler ataced to the header via silicone seal similar to a tuned pipe.

I have PA .65 RE ,(what an engine) with a cut down header pipe and
a CVEC dual exhaust muffler(used on RC race cars). It is very quiet
similar to a tuned pipe sound. It appears to have lots of volume
1.5 dia and 4.78 long.Today was the ist attempt to use it in a plane.
It seems like and others who observed agreed that I will have to increase the inside diameter of the two exhaust tubes in order to make this work? If it is possible could Randy comment on the C/F Re muffler (
(looks like a tuned pipe except very short like a muffler), and what he might think I would have to do (exhaust tube inner dia to get the CVEC
muffler to work? Thank You very much.I gutted the inside of the CVEC
muffler.

RandySmith:
HI Walter

What you saw was a Merlin series PA 40 ultralite with one of our CF slide on mufflers. We also have the same muffler in Aluminium.

I would need to see the muffler you are talking about to give exact details, however I can say with an almost certainty that you would need to open up that muffler as much as possible for use with The 65. and  you will need to  run a  larger venturi.
The mufflers as opposed to pipes, seem to alway have the motor acting like the venturi is much smaller. So if you run the exact motor on a pipe then a muffler, the motor wants about 2 or 3 steps larger on the venturi size.
Try to open the venturi 2 number drill sizes larger (example #12 to #10) and make sure the muffler is opened up as much as you can

Please let me know how this is going either  here or  at my email
randyaero@msn.com

Regards
Randy

Walter Hicks:
WOW!

  Thank you very much Randy for the information I really appreciate it.

Check you  email re C/f muffler.

Question #3- Can you drill the PA venturi to a larger dia or does this

mess up the venturi? Otherwise if I want a larger venturi do I have to

purchase a larger one or can I do the usual drill it myself? Thanks

RandySmith:
Hello Walter

The best way is to send it back to me and i can open them up and recut the proper angles in them. I do not charge for this service, only thing you will pay is shipping.
To answer your question more direct, you can normally get by with 1 drill size bigger, but the larger you drill a true venturi, the more you make it a tube, and it is not as effective.

Regards
Randy

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