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Posted for "Ed Anderson" <eanderson@carolina.rr.com>:
Are you using these "CC inserts" from this company, or are you using a
home made copy? What material are they made of, and how are they holding
up? How close are they to the exhaust port? How did the sound level and
power change after you inserted them?
Mike, these are the commerical ones form the company. At $49, it seem worth
the price compared to my time and cost of materials. They appear to be
heavy gauge steel (but not stainless). Mine are approx 20" from the exhaust
ports. The power was unaffected (as best I can tell) and the harshness of
the exhaust was considerably reduced but it was still not what you would
call "quite"., it was just better. I wanted to take some sound meter
readings of before and after, but just did not get around to it. I can tell
you though it makes a big difference compared to no muffler. When I took
off on the first flight after the installing the inserts one of my muffler
pipes backed off the header and this happend just as I reached pattern
altitude. The difference in sound level was tremendous without the insert
in the exhaust flow. Heart took a leap or two before I realized what had
caused the great increase in volume of sound. Fortunately, I have a
retention system should the front end of the muffler back out so it won't
stick down and act like a pole vaulters pole on landing {:>).
When I attended the Memphis flying in May I did a number of WOT run ups
inorder to get my prop dynamically balanced by an indivdual offering that
service there. The comments about the exhaust volumn was that it was no
louder than a lycoming at full bore although it did have a more high
frequency tonal quality to the sound.
Ed Anderson
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