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Cox Engine of The Month
August-2024
balogh's
![](https://i.servimg.com/u/f95/15/46/86/41/1_balo14.jpg)
"Cox TD09 R/C Beast of Burden featuring Kamtechnik head and DIY metallic fuel nipple"
![](https://i.servimg.com/u/f95/15/46/86/41/sponso12.png)
PAST WINNERS
balogh's
![](https://i.servimg.com/u/f95/15/46/86/41/1_balo14.jpg)
"Cox TD09 R/C Beast of Burden featuring Kamtechnik head and DIY metallic fuel nipple"
![](https://i.servimg.com/u/f95/15/46/86/41/sponso12.png)
PAST WINNERS
muffler mod thoughts
Page 1 of 1
muffler mod thoughts
Got the current production 0.049 mufflers with the small hole.
I was wondering if people already mounted a Pressure Nipple on these and then use fuel tubing to guide the exhoust away from the model.
How much power would this robb from the engine? And would this reduce the sound even more?
thoughts?
I was wondering if people already mounted a Pressure Nipple on these and then use fuel tubing to guide the exhoust away from the model.
How much power would this robb from the engine? And would this reduce the sound even more?
thoughts?
cmulder- Gold Member
- Posts : 279
Join date : 2022-02-10
Re: muffler mod thoughts
I have modified the Cox muffler with the little hole with a thick wall K&S brass tubing.
![muffler mod thoughts Img_0204](https://i.servimg.com/u/f13/20/19/65/06/img_0204.jpg)
![muffler mod thoughts Img_0205](https://i.servimg.com/u/f13/20/19/65/06/img_0205.jpg)
![muffler mod thoughts Img_0206](https://i.servimg.com/u/f13/20/19/65/06/img_0206.jpg)
I used a 1/4" od brass tubing and thread the outside of it 1/4-28 (fine thread) and I also tapped the original "small" hole
the same size.
Then, I retaped a nut the same 1/4-28 thd. and I used a touch of JB Weld on the nut
You could probably just use JB Weld instead and not worry about using a nut?
The tubing is long enough to get most of the exhaust oil away from the airplane. About 2" long.
![muffler mod thoughts Img_0204](https://i.servimg.com/u/f13/20/19/65/06/img_0204.jpg)
![muffler mod thoughts Img_0205](https://i.servimg.com/u/f13/20/19/65/06/img_0205.jpg)
![muffler mod thoughts Img_0206](https://i.servimg.com/u/f13/20/19/65/06/img_0206.jpg)
I used a 1/4" od brass tubing and thread the outside of it 1/4-28 (fine thread) and I also tapped the original "small" hole
the same size.
Then, I retaped a nut the same 1/4-28 thd. and I used a touch of JB Weld on the nut
You could probably just use JB Weld instead and not worry about using a nut?
The tubing is long enough to get most of the exhaust oil away from the airplane. About 2" long.
sosam117- Diamond Member
- Posts : 1318
Join date : 2016-03-23
Location : Suburb of Chicago, Illinois
Re: muffler mod thoughts
The point is the black annulus ring on the top of these mufflers cannot seal perfectly along its edge, and especially if the backpressure inside the muffler is increased by the added choking of a long small diameter extension tube, more castor will leave the muffler uncontrolled along the circumference of this ring.. You may try to wrap the edge of the ring in the teflon tape plumbers use to seal threads, but cannot completely stop castor oozing at the edge.
And yes, the extension tube increases the backpressure of spent gases in the muffler, and robs the power of SPI engines even more than stock mufflers.
And yes, the extension tube increases the backpressure of spent gases in the muffler, and robs the power of SPI engines even more than stock mufflers.
balogh- Top Poster
Posts : 4852
Join date : 2011-11-06
Age : 65
Location : Budapest Hungary
Re: muffler mod thoughts
balogh wrote:The point is the black annulus ring on the top of these mufflers cannot seal perfectly along its edge, and especially if the backpressure inside the muffler is increased by the added choking of a long small diameter extension tube, more castor will leave the muffler uncontrolled along the circumference of this ring.. You may try to wrap the edge of the ring in the teflon tape plumbers use to seal threads, but cannot completely stop castor oozing at the edge.
And yes, the extension tube increases the backpressure of spent gases in the muffler, and robs the power of SPI engines even more than stock mufflers.
Well you could always modify a Enya .049 muffler to fit to your Cox .049 engine.
These mufflers seal well and the back pressure is way less than the Cox mufflers.
As for Cox engines with SPI, I would not use a muffler on them because it "needs" clean air for it to work.
![muffler mod thoughts 037_co12](https://i.servimg.com/u/f13/20/19/65/06/037_co12.jpg)
![muffler mod thoughts 038_co13](https://i.servimg.com/u/f13/20/19/65/06/038_co13.jpg)
![muffler mod thoughts 036_en10](https://i.servimg.com/u/f13/20/19/65/06/036_en10.jpg)
As for the modified Cox muffler with the brass tube.
The inside diameter is just a little bit larger than the "old" stock Cox muffler that had the aerodynamic extension on it.
![muffler mod thoughts Cox_rc12](https://i.servimg.com/u/f13/20/19/65/06/cox_rc12.jpg)
![muffler mod thoughts Std_co10](https://i.servimg.com/u/f13/20/19/65/06/std_co10.jpg)
And the brass tubing "extension" is much less restrictive than the Cox car muffler.
![muffler mod thoughts Car_mu10](https://i.servimg.com/u/f13/20/19/65/06/car_mu10.jpg)
sosam117- Diamond Member
- Posts : 1318
Join date : 2016-03-23
Location : Suburb of Chicago, Illinois
first version
So the first try i installed a "m3" size fitting. if this is too restrictive then i also have the "m4" size.
Even the "m3" has a much bigger diameter then the original hole so should be less restrictive then original without aditional tubing
lets see what happens
Even the "m3" has a much bigger diameter then the original hole so should be less restrictive then original without aditional tubing
lets see what happens
cmulder- Gold Member
- Posts : 279
Join date : 2022-02-10
![-](https://2img.net/i/empty.gif)
» WTB .049 muffler or muffler parts
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» Cox Texaco Thoughts
» Buying used Cox engines
» Thoughts on buying a tee dee rc 09?
» Another proposed design by Roddie
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