Good question^^^

 

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.

 

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.

 

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.

 

i did mine before 3 days ago , now i have no drone at any speed

thanks op

 

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?

 

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!

 

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.