Quiet down a P2R IPD exhaust?

[mopar318]

Anyone else have this cat-back exhaust and think its abnormally droney/loud? It drones way louder than the stock exhaust with the resonator removed and rusted out muffler. I'm wondering if the rear muffler is the issues on this. Thoughts?

 

[Jack]

I have one of the first OBX p80 exhausts on my 850. So similar in a way
The original muffler got super drony. I replaced it with a borla of same size, made it a whole lot better but then I added another small borla resonator about the middle of the car.

No mote annoying drone. Car is loud when I step on it but does not drone. The old muffler burned out

 

[poulrais]

My S60r has no CAT, a 3 inch dp, 3 inches all the way back with a 5 inch Vibrant resonator and a Magnaflow muffler at the back. It sounds amazing at idle and on accel but the drone is massive when cruising or accelerating at low rpm. I'm about to slap on a high flow CAT hoping it'll quiet it down a bit.

 

[Jack]

My S60r has no CAT, a 3 inch dp, 3 inches all the way back with a 5 inch Vibrant resonator and a Magnaflow muffler at the back. It sounds amazing at idle and on accel but the drone is massive when cruising or accelerating at low rpm. I'm about to slap on a high flow CAT hoping it'll quiet it down a bit.

High flow cat won’t do that

 

[poulrais]

High flow cat won’t do that

Damn... Then it'll have to be a muffler with an electric bypass?

 

[andyb5]

My S60r has no CAT, a 3 inch dp, 3 inches all the way back with a 5 inch Vibrant resonator and a Magnaflow muffler at the back. It sounds amazing at idle and on accel but the drone is massive when cruising or accelerating at low rpm. I'm about to slap on a high flow CAT hoping it'll quiet it down a bit.

For a low-restriction approach to reducing drone, use a sound spectrum analysis app on your cell phone to identify the frequencies that drone the loudest, then add a Helmholtz resonator (EDIT: or 1/4 frequency resonator / “j pipe”) that is sized for the frequency that needs to be eliminated.

Should cut out the annoying frequency while cruising and still leave all the fun noises

 

[poulrais]

For a low-restriction approach to reducing drone, use a sound spectrum analysis app on your cell phone to identify the frequencies that drone the loudest, then add a Helmholtz resonator that is sized for the frequency that needs to be eliminated.

Should cut out the annoying frequency while cruising and still leave all the fun noises

Oh! I will try this! Thanks!

 

[poulrais]

Looks like my drone is in the 79-82 Hertz range... How do I calculate the size if the resonator?

 

[andyb5]

Either site should work. The first one describes the methodology and has a pair of spreadsheets you can download. The second one has the calculators built in, but doesn’t give as much info on how to define the calculation parameters, so I’d refer to the 1st site for that info.

Drone Reduction - Wilhelm Raceworks, LLC

Adding a Helmholtz resonator to my center exit exhaust for done reduction. Calculator to design a Helmholtz to solve your own drone problem.

wilhelmraceworks.com

Helmholtz Resonator Calculators - Exhaust J-Pipe Length - StrikeEngine

Find the hypothetical length of your J-Pipe/Helmholtz resonator with this Helmholtz resonator calculator. I also show you how to get the numbers you need

strikeengine.com

 

[poulrais]

Either site should work. The first one describes the methodology and has a pair of spreadsheets you can download. The second one has the calculators built in, but doesn’t give as much info on how to define the calculation parameters, so I’d refer to the 1st site for that info.

Drone Reduction - Wilhelm Raceworks, LLC

Adding a Helmholtz resonator to my center exit exhaust for done reduction. Calculator to design a Helmholtz to solve your own drone problem.

wilhelmraceworks.com

Helmholtz Resonator Calculators - Exhaust J-Pipe Length - StrikeEngine

Find the hypothetical length of your J-Pipe/Helmholtz resonator with this Helmholtz resonator calculator. I also show you how to get the numbers you need

strikeengine.com

Yes I already visited those 2 sites this afternoon and I'll also use the spreadsheet. Looks like I'll need a 6 inches long .88" diameter neck with a 4 inch diameter and 6 inches long canister. Does it matter where on the exhaust line this is fitted?

 

[andyb5]

From what I can tell, I don’t think so

 

[mertz]

Thanks for posting up the links. Looks like exactly what I need to tone down this awful drone.