Exhaust Drone Fix
09-09-2008 | 05:51 AM
#31
I know this is mainly for drone but I wonder how well this would work for eliminating rasp, if at all? Mine doesn't really drone but rasps so bad at 2300-2800 that it will make you cringe and old people run and duck for cover.
09-09-2008 | 07:42 AM
#32
I need to know what RPM the drone is worst in your truck. Also what size engine do you have on it? Maybe take it out for a short drive and get on the freeway or up a slight hill and really try to find the exact RPM. Then I can give you a length that would be good to shoot for.
If you do make it, are you going to try to make it adjustable like the design i drew up? It might be helpful to be able to fine tune it. Every truck is a little different.
Just curious, you have single or dual exhaust?
By the way, thats exactly how my friend's sounds. The same at WOT and idle, but the drone is gone
If you do make it, are you going to try to make it adjustable like the design i drew up? It might be helpful to be able to fine tune it. Every truck is a little different.
Just curious, you have single or dual exhaust?
By the way, thats exactly how my friend's sounds. The same at WOT and idle, but the drone is gone
09-09-2008 | 01:26 PM
#33
I went to my muffler shop today and they built an exhaust for a VW as a prototype for APR a local VW and Audi tuning company. Anyway, Corsa sent a muffler and a resonator for them to try and see what fits on the VW. They ended up having a resonator left over and given it's size and shape it wouldn't fit many vehicles. Expect it was perfect behind the muffler right before it goes over the rear axle. I will try and get some pictures. Now I have 0 drone and it is so much quieter. I am very happy
09-09-2008 | 02:52 PM
#34
I went to my muffler shop today and they built an exhaust for a VW as a prototype for APR a local VW and Audi tuning company. Anyway, Corsa sent a muffler and a resonator for them to try and see what fits on the VW. They ended up having a resonator left over and given it's size and shape it wouldn't fit many vehicles. Expect it was perfect behind the muffler right before it goes over the rear axle. I will try and get some pictures. Now I have 0 drone and it is so much quieter. I am very happy
09-10-2008 | 01:11 AM
#35
Thread Starter
On The Tree
Joined: May 2008
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From: nor-cal
I went to my muffler shop today and they built an exhaust for a VW as a prototype for APR a local VW and Audi tuning company. Anyway, Corsa sent a muffler and a resonator for them to try and see what fits on the VW. They ended up having a resonator left over and given it's size and shape it wouldn't fit many vehicles. Expect it was perfect behind the muffler right before it goes over the rear axle. I will try and get some pictures. Now I have 0 drone and it is so much quieter. I am very happy
09-18-2008 | 01:05 AM
#36
Thread Starter
On The Tree
Joined: May 2008
Posts: 110
Likes: 0
From: nor-cal
I was playing around and graphed the equations for the exhaust.
The frequency note of an engine = ( RPM's ) x ( number of cylinders ) / 120
Which looks like this: This graph shows the frequency note that the exhaust produces as RPM increases.
Then using that equation, set it equal to the frequency produced by the branch resonator.
You have to use a calculator to find the speed of sound as temperature changes. I used 150 degrees fahrenheit. Here is the link for the calculator
Resonator frequency = ( Speed of sound ) / ( Length of pipe ) / 4
Set them equal and solve for Length. RPM is then your explanatory variable.
Then you get a graph like this. RPM's is on the horizontal and the proper length of pipe for the branch resonator is on the verticle axis.
So pretty much you find out the RPM where the drone is loudest and use the second graph to find the proper pipe length for a resonator.
To find the exact length, Take 54,491.4 and divide your RPM into it. Say your drone is at 1900 RPM. Take a calculator and type 54,491.4 / 1900 and it will equal 28.679 inches.
The frequency note of an engine = ( RPM's ) x ( number of cylinders ) / 120
Which looks like this: This graph shows the frequency note that the exhaust produces as RPM increases.
Then using that equation, set it equal to the frequency produced by the branch resonator.
You have to use a calculator to find the speed of sound as temperature changes. I used 150 degrees fahrenheit. Here is the link for the calculator
Resonator frequency = ( Speed of sound ) / ( Length of pipe ) / 4
Set them equal and solve for Length. RPM is then your explanatory variable.
Then you get a graph like this. RPM's is on the horizontal and the proper length of pipe for the branch resonator is on the verticle axis.
So pretty much you find out the RPM where the drone is loudest and use the second graph to find the proper pipe length for a resonator.
To find the exact length, Take 54,491.4 and divide your RPM into it. Say your drone is at 1900 RPM. Take a calculator and type 54,491.4 / 1900 and it will equal 28.679 inches.
09-19-2008 | 03:54 PM
#37
Just got my 22" Magnaflow muffler in the mail yesterday, putting that on this weekend, then if there is still the drone, doing the branch resonator. I'll post up the results. Thanks for all of the info TS77!
09-19-2008 | 09:10 PM
#39
I have been meaning to get some pictures of what I did but I keep forgetting. I have all next week off, so I will take some pictures of it and the SS rear bumper I have in the garage I need to sell. I have had my setup almost two weeks now. I am VERY happy. It seems that it hurt the bottom end a little bit.