That Is where either calculation or experimentation comes in. Notice it looks like it has an adjustable length? That is so it can be tailored to a certain sound frequency, aka drone.
Its welded to the tail pipes after the mufflers both sides. There's a welded in cap on the adjustable end. If you look at the Pypes lineup of mufflers they say the Race Pro is their quietest. It's a straight thru packed like a Magna Flow. Before the J pipe install I tried bottle resonators in the mid pipes behind the X pipe ,drone. Then I tried Magna Flow chambered mufflers, sounded great but still droned right at cruise 1500/1800 rpm and idle. J Pipes (helmholts) no drone at any RPM. Back in the day we wanted as much volume and drone as we could get.
not so much now I'm older.
The drone (resonant frequency) is gone at all rpm but when I stand on it the exhaust tone is all there. No restriction either.
Hi, I have read up on Helmholtz resonators as I too have a bad drone at cruising rpm 188-2100 ish! I have seen the pictures of what you have made and I’m going to give it a go on my 360 duster! Could I just ask you what size tubing you used? My pipes are 2.5” so I was thinking 2” for the resonator? Calculating show I need to make total length in the region of 25”.
Chris,, mine are 2.25" they are mandrel bent (I dont think they have to be) and are adjustable from 30" to 38". I have them on my 2.5" tailpipes. I dont hear a real big difference with the range of adjustments only slightly. I run them now at 38" and it tames the drone perfectly. These were designed, made and sold by a local muffler shop and they use them on all the mid pipes when they install performance exhaust on all the modern muscle cars (ford, chev, and Mopar.) I dont think they have to be curved either. Good luck and let us know how they work out. Cheers. Larry
