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  #11  
Old 10-20-2017, 04:45 AM
JohnInReno's Avatar
JohnInReno JohnInReno is offline
 
Join Date: Jun 2005
Location: Prescott Valley/Chandler AZ
Posts: 293
Default Cut existing?

Quote:
Originally Posted by rjcthree View Post
Can the standard Vetterman pipes be cut at an angle close to parallel to the fuse floor to come close to the turn down effect? I'd rather not add weight or parts. Does anyone have experience with this?
I too am interested in this. My exhaust sticks down at an angle and it looks like a cut parallel to the fuselage would help. However, I know Vetterman would be the answer man.
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  #12  
Old 07-12-2018, 12:34 AM
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AJ85WA AJ85WA is offline
 
Join Date: Sep 2011
Location: Perth, Australia
Posts: 267
Default Any info on this

I am still interestedd in this? Will a standard pipe cut down as suggested have the same results as a clamp on trun down tip?

Where have you guys purchased the turn down tips from?
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  #13  
Old 07-12-2018, 09:07 AM
Lars Lars is offline
 
Join Date: Nov 2005
Location: Davis, CA
Posts: 1,031
Default

Quote:
Originally Posted by edsong View Post
I wish they would quit calling our heat exchangers mufflers. They do nothing to (muffle) the exhaust noise.

Eddy
To clear that up, Vetterman calls them mufflers because that's what they are. They are optional, and are described on the company website about half way down: http://www.vettermanexhaust.com/

Vetterman claims a 6dB reduction in sound pressure over straight pipes, as noted on the page linked above. I have a set on my vertical induction Lyclone in my RV-7. I've never flown it with straight pipes so I can't comment on personal experience with noise reduction. They are bulkier than the Robbins Wings heat exchangers (heat muffs) that Vetterman provides for cabin heat on the straight pipe systems. The muffler system is also heavier than straight pipes, by about 2 pounds as I recall.

Can't comment on cabin heat improvement either, but I can say that the amount of cabin heat available from the mufflers on my RV-7 will have you looking for the exits on the coldest days if the heater valve is wide open. I've flown with an OAT of -20 degrees F and wide open was still too much.
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Last edited by Lars : 07-12-2018 at 09:11 AM.
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  #14  
Old 07-12-2018, 10:59 AM
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Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 1,734
Default

I only have one heat muff on my straight pipe system. 20 F and higher is my limit but I am also a southern GA transplant. I don't fly in colder WX
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Last edited by Raymo : 07-13-2018 at 09:48 AM.
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  #15  
Old 07-12-2018, 05:13 PM
vetterman vetterman is offline
 
Join Date: Oct 2006
Location: TX
Posts: 37
Default Mufflers

I will try to answer a couple of item here. I tested the noise level of both the standard tail pipe system and the muffler system and yes there was a 6 dB difference. One guy was fussing about calling them “mufflers” but in the context of reducing noise it’s a common word. Go back in history of some planes like the cub and the unit was called a “spark arrestor” then one day later on it was called a muffler. Go figure. So the unit with a flame cone is not a true muffler by automotive standards but it does a good job of providing really good cabin heat and reducing noise a little. I might add one note here regarding noise. There’s the prop blast on the airframe, 200 mph of wind on the fuselage and air entering the cowl inlets and on and on- so the exhaust is what’s causing the noise inside. Really!!!
Now to address trimming tail pipes. I tested almost every combination I could think of and really never found any difference in performance, but what I did find is you don’t want the exhaust exit to be exposed to 200 mph of wind. That’s the ol “banana in the tailpipe syndrome” . Reminds of the time I got a call and the guy said all of the slip joints were leaking. The pictures he sent of how his tailpipes were cut solved the problem. Bottom line is leave the pipe as is, it was designed that way for a reason.
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