How long is your J-pipe / HelmHoltz resonator?

[natepcbfl]

Guess I am gonna try a 23.5" pipe. See if i can get some of it down low and some a little higher at the same time. I drive at 65-70 most of the places I go which is the 140hz 2k-21k or so RPM range in 6th just cruising. So if down low its not getting it enough to make the gf stop giving me that look I'll just speed up a little lol.

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[Jay-rod427]

You could get fancy with your fab and make it adjustable to fine tune it. Simple slip joint like Solo does.

 

[natepcbfl]

You could get fancy with your fab and make it adjustable to fine tune it. Simple slip joint like Solo does.

Yea I had thought about that. I live in N Alabama and most exhaust shops here have no idea what a J-pipe is. They are plenty capable of making and installing them though. Just tell the place I am about to go to what you want and they can do it from what I have been told. I am going to have them weld up what I clamped on in the garage over the weekend so that will leave me with 2 wide exhaust clamps.

 

[H@mmer]

Best guess I'd say +\- 200 maybe 250 rpm. So I'd say if you target 2,000 you won't catch the 2,500... 2,200 at best on the high end of the range.

Could you do one pipe at a length to grab the 2k rpm drone and another pipe at a different length to get the 2.5k rpm drone?

 

[Jay-rod427]

Could you do one pipe at a length to grab the 2k rpm drone and another pipe at a different length to get the 2.5k rpm drone?

Yes you could! but would have a 4 pipe tangled mess underneath.

 

[kenbidwell]

Last weekend I had 28 inch J-pipes installed on my 2015 GT PP after putting on the Steeda axlebacks. Drone seemed to be about 1200 and then again at 2200. I went with 28 inches to try and cover both rpm ranges. After the J-pipes I still have a drone around 1200 but I have to lug it down in 6th gear to make it happen. There is a slight sound around 2200 that my son says is just engine noise but I still consider it to be drone. My son has a 2013 GT that is twin turbocharged so he is used to much more interior noise than I was. Overall I would say the J-pipes removed about 90-95% of the drone. I was thinking of shortening the pipes to the calculated length for 2200 rpm but I am not sure it is worth the hassle. It is not as quite now as it was with the stock exhaust but I guess that is kind of the point for installing aftermarket, the sound. It sounds great now, nice growl that it didn't have with the factory system. I guess drone is in the ears of the listener, many people say that the Steeda axlebacks do not drone. I would disagree. I first installed Roush axlebacks when I first got the car and the drone was terrible, still others say that the Roush axlebacks don't drone either. I strongly disagree. Guess you just have to go with what you like, and the addition of the J-pipes has made the difference in being able to put up with the new mufflers or actually liking the sound, which I do now!

 

[H@mmer]

Yes you could! but would have a 4 pipe tangled mess underneath.

Hmm.
So, even though the exhaust pulses are balanced side-to-side via x-pipe, you couldn't install a single j-pipe of length "L" on one bank and a second j-pipe of length "L + x" on the other bank? In lieu of two pairs?

 

[Jay-rod427]

Maybe to a small degree the pipes are balanced by h or x. Good question. No idea.

 

[natepcbfl]

Hmm.
So, even though the exhaust pulses are balanced side-to-side via x-pipe, you couldn't install a single j-pipe of length "L" on one bank and a second j-pipe of length "L + x" on the other bank? In lieu of two pairs?

So if two different lengths were used it would for sure have to go before the X-pipe I would imagine. Or what about if there was an H-pipe, could two be put there one each side of the H connection? After getting this car I want to be back turning wrenches again so bad, instead of this PC and desk. Sure is easier to test this stuff when you have the facilities.

 

[BmacIL]

There are still discrete pulses going through each pipe. You need a resonator on both banks.

 

[H@mmer]

It's definitely something I would love to test if I had a lift and welder available.
Not worth it to me to try and pay an exhaust guy to do multiple iterations.

 

[natepcbfl]

There are still discrete pulses going through each pipe. You need a resonator on both banks.

Well I guess it was at least worth asking. Even if it didnt get rid of all the drone but covered a broader range I would be happy.

 

[Orange_cru$h]

If i put the HelmHoltz in the middle of the H pipe would you guys think it will work? One Pipe for both banks and pulses.

 

[JM7225]

So drone has become a hot topic lately. Figured I would start a thread for people to list EXACTLY what exhaust they have and how long of a J-pipe / HelmHoltz resonator they put on to stop the drone for an easy reference for others.

:ford:

I had 26" J-pipes on my MRT exhaust and the drone was 100% gone. They were 2.5" in diameter. Smaller diameter pipe = less resonance negated.

 

[5cent]

I have 3.31 gears with legato mufflers and xpipe. Love the sound. But 6th gear 1800 to 2100 if I give it gas drone takes over. Wanting to try the j pipes. I thinking I need 25 inch if it's a +/- 200. Is that right?

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