Drone Reduction
Laughing Gas
Joined: Jun 2010
Posts: 1,035
Likes: 330
From: Waterford, VA. USA
New User
Joined: Jun 2013
Posts: 10
Likes: 0
Expanding just a little from Topdown...
your system looks nice and symmetrical. Other words, both sides are exactly same shape, same pipe diameter, mufflers in exact same place, all bends in exact same place but mirror image, and tips same placement. I'm also guessing that from the x-over pipe to the muffler, is almost exactly 1/2, 1/3 or 1/4 the distance from back end of muffler to the exhaust tip. That means everything is going to resonate at one frequency, and then multiples of that frequency. And I bet you already know what the frequency (or RPM) is.
An easy, quick and cheap method to move or separate the resonances, would be to cut one of the mufflers out of the system, with 3-4" of pipe on one end and at least 12" of pipe on the other end. At least a foot of pipe on the long end would be best, more is better. Then flip the muffler and pipe, end for end, and re-install in the system. yes, it will look goofy from underneath, but it will get the left and right side pipes to resonate at slightly different RPM (frequency). If it doesn't work enough, you can put it back. That also means you need a bigger difference between left and right sides.
Ford had to do something similar on the Lincoln Mk VII with the 5.0. Since they had the option of almost anything, they used slightly smaller pipes and muffler on one side, compared to the other. Couldn't have a luxurious Lincoln 'droning' on the highway. Lots of Lincoln MkVII 'rodders used fox-body mustang exhaust systems, and then complained about all the 'drone'. Mustang systems had same size pipes on both sides.
Could also use different sized (length is easiest) mufflers between left and right side. Anything to help break up all the resonance in the system. There are also 'in-line' type resonators that could be put in one side of the system. Another option would be to install double wall 'resonator tips' on each tip, but use different length on each side. but that would be more visible from the outside.
your system looks nice and symmetrical. Other words, both sides are exactly same shape, same pipe diameter, mufflers in exact same place, all bends in exact same place but mirror image, and tips same placement. I'm also guessing that from the x-over pipe to the muffler, is almost exactly 1/2, 1/3 or 1/4 the distance from back end of muffler to the exhaust tip. That means everything is going to resonate at one frequency, and then multiples of that frequency. And I bet you already know what the frequency (or RPM) is.
An easy, quick and cheap method to move or separate the resonances, would be to cut one of the mufflers out of the system, with 3-4" of pipe on one end and at least 12" of pipe on the other end. At least a foot of pipe on the long end would be best, more is better. Then flip the muffler and pipe, end for end, and re-install in the system. yes, it will look goofy from underneath, but it will get the left and right side pipes to resonate at slightly different RPM (frequency). If it doesn't work enough, you can put it back. That also means you need a bigger difference between left and right sides.
Ford had to do something similar on the Lincoln Mk VII with the 5.0. Since they had the option of almost anything, they used slightly smaller pipes and muffler on one side, compared to the other. Couldn't have a luxurious Lincoln 'droning' on the highway. Lots of Lincoln MkVII 'rodders used fox-body mustang exhaust systems, and then complained about all the 'drone'. Mustang systems had same size pipes on both sides.
Could also use different sized (length is easiest) mufflers between left and right side. Anything to help break up all the resonance in the system. There are also 'in-line' type resonators that could be put in one side of the system. Another option would be to install double wall 'resonator tips' on each tip, but use different length on each side. but that would be more visible from the outside.
Thread
Thread Starter
Forum
Replies
Last Post
fordmania
1948 - 1956 F1, F100 & Larger F-Series Trucks
20
Jun 6, 2019 09:10 AM
yankeerebel
1973 - 1979 F-100 & Larger F-Series Trucks
4
Apr 21, 2010 05:25 PM
