Pypes Turbo Pro

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@LJ67barracuda340 have you found a different RPM where the resonant frequency moved to? Or did the J pipe move it to an RPM range where you never see?
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.
Length can be calculated from info on line if you Google helmholtz resonator, or you can use one that is adjustable.
And yes, the end has to be welded shut, to reflect the sound wave back into the exhaust pipe.
 

LJ67barracuda340

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That J pipe - is that welded into your exhaust aft of the muffler? And is it a closed end pipe? Couldn't tell from the photo bur it looks like it is. And you have one for each exhaust line? I'm impressed by the engineering but I'm going with a quieter muffler rather than that. I'm no acoustical engineer and it's just hard to believe that drone is that hard to solve. Back in my younger days, I admit a long time ago, we bought whatever performance muffler was available and drone was never mentioned. Thanks for all the help guys.
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. :lol: not so much now I'm older.
 
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chris norman

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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”.
Thanks Chris
 

LJ67barracuda340

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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”.
Thanks Chris
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
 
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