#### Redbob

##### Well-known member

If I could recall the exact frequency of the boom problem, it's a fairly simple calculation to predict the required position of the X-over pipe, based on quarter-wave theory. I'd also have to guess at the gas temperature, which affects the speed of sound in the pipe.

You have to know, however, that the problem noise is coming from the exhaust. Assuming that it is, I think the best position is just ahead of the rear axle, near the point where the two pipes split apart to run out to the two mufflers. It does not have to be exact in order to be effective. Plus or minus several inches should be OK since the wavelength of the sound involved is quite long.

I've attached a very crude sketch I made to illustrate some of what I'm describing. Note that the temperature 'T' in the formula is the gas temperature, and a reasonable guess at this is 450F.

You can see, though, that the frequencies will change depending on engine load, since that will change the gas temps.

- R