Today's Project: Exhaust Quarter Wave Tube

[nrubenstein]

(Often referred to as a helmholtz resonator, although they are technically different.) I re-did my exhaust yet again because of the 6 speed's clearance issues (the bracket and the exhaust tube wanted to occupy the same space), and because I was tired of having a plain 3" tube sticking out the rear valence. It looks fine on a 318, with the single tip valence, but the gap on a 325 just needs two tips (or to be filled in, but I didn't want to go down that road...).

Unfortunately, the new Borla had an annoying drone right at cruising speed. I decided that rather than try different mufflers yet again that I would attack the problem directly.

I have to say that I am thrilled with the results. The exhaust is now virtually silent cruising at 70, where before it had a really annoying spike at about 140Hz. Even better, the tube dramatically cut down on the 1,800-2k drone that I wasn't bothered enough by to try to attack (the tube would have been 40" long instead of 27" in that case).

Even better, I assembled it entirely out of leftover scrap, so my total cost is zero.

So... Here they are: