Quieting exhaust noise

[69427]

Going to be welding up a new exhaust system in the near future, but I'd like this system to be a bit quieter than the present one. To be honest, the exhaust note/noise out the back ain't bad, as it's not that loud. It's the underbody section that rings like a tinny bell with each exhaust pulse out of the header collectors. I'm trying to understand the mechanism. Is it a pressure pulse that's hitting the pipe walls, and making them ring like a bell (sort of like detonation excites the cylinder walls and makes that characteristic knock noise)? I'll be taking out the present 2.5 inch tubing and running some 3 inch tubes. These bigger tubes should theoretically resonate at a lower frequency, and along with the slightly greater mass (a three inch tube of similar wall thickness would weigh more), and the greater interior volume that would reduce the instantaneous pressure peaks, I'm thinking this might quiet down some of this ringing. I'm also thinking of trying to maximize the common plenum volume (both banks feed into a large single pipe) in the system to assure that both mufflers see the same pressure. I've got that on the present system, and the exhaust note seems to have a slightly more subdued note to it, in that there aren't the loud single pulses coming out the pipes.
Okay, back to my original question: What is the mechanism that makes the underbody pipes so noisy?

thanks,
Mike

 

[1Michel]

Is it SS?
Maybe Stainless steel gives more of a bell clink ring than softer aluminized steel.
Just a thought
Maybe wrap them up under the body.

 

[mrvette]

Every set of headers I know of had a certain high freq 'tink' to them...with any 1/2 quiet stockish system, and the headers not shrouded with metal or wrapping, they all 'tink'.....I dunno how else to describe it....

:drink:

 

[69427]

Is it SS? Not the present setup. I used to have a SS set of duals, but I did some calculations and measurements and found out I could save some weight by going with my present mild steel setup.
Maybe Stainless steel gives more of a bell clink ring than softer aluminized steel. I do recall the old SS setup having a similar tinny ring while the engine was idling.Just a thought
Maybe wrap them up under the body.

We're thinking along similar lines. That would certainly dampen the noise, but I'd sure like to reserve that as a last resort.

 

[1Michel]

I asked about th SS because I know a few guys that complained about the clink pinking noise of stainless steel and even if it's more durable they wont use them.
Big deal, SS is tougher and looks nicer but harder and more expensive to weld + it's not a daily driver so it'll last a long time anyway.
I also know that wraping some Hooker's (friend of mine did that on a Nova) will void the warranty because of higher heat and corrosion.