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How to build an exhaust resonator tube to eliminate drone

Old 10-22-2013, 03:46 AM
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Good question^^^
Old 10-22-2013, 11:38 AM
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Keep in mind the speed of sound will be higher inside the exhaust. 343 m/s is for sea level standard day conditions. The exhaust gases are much hotter and a mixture of air/fuel is present. The resonator tube is not passing exhaust however, so the temperature of the air inside it will not be as hot as the exhaust flow. I would use a value more around 400 m/s.
Old 10-22-2013, 12:06 PM
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That is why I made sure to note the temperature dependence in the first post. And yes, it works for any frequency that you wish to attenuate.
Old 10-31-2013, 08:10 PM
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Does the resonator have to be after the muffler? I would think before the muffler would have the same affect of canceling out the wave.
Old 05-18-2014, 08:45 AM
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i did mine before 3 days ago , now i have no drone at any speed

thanks op
Old 07-27-2014, 08:50 AM
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now i'm just wondering...some people say you go 180 and point the resonator towards the engine.what is the difference?? and yes does it make a difference to do it before or after the muffler?

Last edited by three8threestker; 07-27-2014 at 08:56 AM. Reason: forget a question
Old 07-28-2014, 11:53 AM
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It makes no difference where you point it, I just put them, shape them where they will fit. I've always put them after the muffler.
Old 07-30-2014, 08:40 PM
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Originally Posted by kbracing96
It makes no difference where you point it, I just put them, shape them where they will fit. I've always put them after the muffler.
thanks for the info!
Old 11-06-2014, 12:13 PM
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I've noticed that the drone occurs at different rpms depending on my trucks temperature. For instance when I first start it up and drive it, I hear the drone right at 1500 rpm. By the time I get home it's droning closer to 1800-2000 rpm.

My question for those of you that have built these tubes is how much of an rpm range is covered by one particular length? If I target the 1500 rpm drone my tube length is something like 32", if I target the droning at 2000 rpm it is 26"...How crucial is the exact length? Thanks for any input!
Old 11-06-2014, 04:50 PM
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Originally Posted by Eckoes
I've noticed that the drone occurs at different rpms depending on my trucks temperature. For instance when I first start it up and drive it, I hear the drone right at 1500 rpm. By the time I get home it's droning closer to 1800-2000 rpm.

My question for those of you that have built these tubes is how much of an rpm range is covered by one particular length? If I target the 1500 rpm drone my tube length is something like 32", if I target the droning at 2000 rpm it is 26"...How crucial is the exact length? Thanks for any input!
That's because sound travels at different speed at different temperature. I think 32 is enough either side of the "drone zone" to get most of it out.

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