Fabricating Exhausts: Minimizing High-Pitched Sounds

[panops145]

Hello,

I am fabricating exhausts and was curious, to minimize the "tinny" or high pitched sounds coming from the exhaust (ricer sounds), do I increase the wall thickness of the tube? I'm assuming this would make it have a deeper overall tone to it.

Mainly exhausts for Subarus, making both unequal and equal length headers. Any information would be appreciated

 

[SteamKing]

When you say 'tube', are you talking about the exhaust pipe or the muffler (silencer for our British friends)?

 

[panops145]

The tubing used to make the exhaust. Disregarding the muffler or silencer all together, how would changing the thickness of the tubing effect the overall tone of the exhaust?

Hope I cleared up your question.

 

[SteamKing]

Probably not too much. That's why people select different mufflers to get different exhaust sounds, in my experience. If you are able to find exhaust piping with widely different gauge material, it might be worth an experiment (if you or your friends own an exhaust shop), but it could get expensive.

 

[panops145]

I custom fabricate headers and catbacks for cars, mainly Subarus, and noticed the difference in the tone and "rasp" between cars.

For example:

Raspy

http://www.youtube.com/watch?v=IpOHc9F6lTA&feature=youtu.be
This is a full exhaust setup from my shop.
It has rasp to it even with a magnaflow muffler, but why? I don't believe it is the muffler causing it, what else could it be?

Deep

http://s675.photobucket.com/user/panops145/media/PanagiotisPanopoulos.mp4.html

 

[HowlerMonkey]

Two chamber mufflers will remove the raspiness you don't want.

Two chamber mufflers are usually more restrictive to you need to go with a bigger size than a single chamber setup.

It will leave you with a deep rumble but no rasp.

Catalytic convertors remove a bit of the rasp as well and some of my turbo cars run only the turbos and the cats as noise attenuators and they sound great.

 

[panops145]

Thank you this added to my research and found Helmholtz resonator is what I'm looking for

 

[HowlerMonkey]

Or you could do this...same result whether before or after a two chamber muffler but the one with the valve on the inlet will be be more quiet than the one with the valve on the outlet because of possible sealing issues.

This is why so many people find magnaflow "straight through"mufflers a bit loud.

 

[Ketch22]

Generally a Humhotlz resonator is used to reduce drone. J-pipes and side chambers are both examples that are used to very good results. As a general rule. the High pitch sounds that lend raspiness are carried in a straight line or reflect well down the inside of the pipe. The low end sounds carry well in reversals due to the pressure wave component being so pronounced. You did quite well in looking to a magnaflow. Keep in mind that anything straight will carry some of that edge. A reversing or V gate type muffler will usually scrub most of the highs off. Some of this style have a pressure activated gate internal so that they reduce back pressure at Wide Open Throttle.

You may also want to look at a Flowmasters series. They have V gate types in the more family end and in a pro series have a packed Delta that has a much deeper tone. It is still pretty good at removing the highs even though straight due to the delta configuration. There are a few good video clips available but none I know of that actually feature subaru's