Exhaust project for turbofabricator

[ijames]

Ken, I know you have tried different exhaust configurations to elminate the dreaded 2000 rpm drone, so take a look at this thread and the links posted in it: using big mufflers as termination box • Speed Talk. I know a couple of guys have used crossflow mufflers in the stock muffler location, but what if a simple tube stub running from each side across to almost the other side would do the same job? Tap them into the pipes that go over the rear axle at the highest point and have them side by side and just clamp them together so they support each other. You need another project, don't you ?

 

[ITSAV6]

C4 Corvettes have the drone awful also. A crossover pipe after the axle helps.

 

[TurboBob]

you would want to tune it I think. (Helmholz resonator..?)

I think the pipes resonate at that frequency, and reflect off the road. Or perhaps they set up some sort of standing wave under the car.

A real study of the phenomenon would be a fun project.

In the interim, my system is awesomely quiet....

Bob

 

[tsm3089]

I put some dynomax vt mufflers on a street car this spring and it made a huge difference.

 

[ijames]

The idea is to tee in a side pipe that is 1/4 wavelength long with a cap at the end. At the frequency that it is 1/4 wavelength long there will be a reflection off the capped end that will exactly cancel the sound in the exhaust pipe before it exits the tailpipe. From what I've read so far the tuning is not that critical, so a pretty wide range of rpms gets the drone significantly reduced. At a reasonable exhaust temperature guess and 2000 rpms with a six cylinder the pipe needs to be about 30-35 inches long, so putting one on each pipe of a dual exhaust and running them cross-ways in front of the gas tank would have the end of one almost touching the main pipe on the other side. I'm just curious if it would work anywhere near as well as the crossflow, and how much lighter would it be?