How long is your J-pipe / HelmHoltz resonator?

My Solo is pretty quiet below the 2100rpm range. Once pass that all hell breaks loose.

I also measured the length of the J pipe. From the weld to the end it's about 34-35 inches long from the factory. Of course it's adjustable.
The chart says it's tuned between 1400-1500 rpm.

I'm also curious about two J pipes of slightly different length. My drone is 130hz to 140hz, and rattles my teeth. Can I use a 24 to 25 on one side and 23 to 24 on the other? Trying to broaden the range of frequencies eliminated. My attachment point will be after my H. Something similar to these pictures I found.

Does diameter matter

Another question will the longer pipe quiet the drone of the shorter pipe?

Meaning if I put a 40 inch j pipe, will it quiet the drone of pipes in the 20 inch to 40 inch range?

dirtwarrior said:

Another question will the longer pipe quiet the drone of the shorter pipe?

Meaning if I put a 40 inch j pipe, will it quiet the drone of pipes in the 20 inch to 40 inch range?

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I don't think diameter has a lot to do with it (I could be wrong) from what I gathered it just depends on the length and that in turn is decided by the actual frequency you are trying to stop. There is a chart on the 1st page of this thread that can give you the length. IMO I would think to use something roughly the same diameter of the exhaust your are using. If you can make a set up as the pictures above posted by Fhbrumb that will give you the best opportunity to remove as much as possible as you can "tune it".

Fhbrumb said:

I'm also curious about two J pipes of slightly different length. My drone is 130hz to 140hz, and rattles my teeth. Can I use a 24 to 25 on one side and 23 to 24 on the other? Trying to broaden the range of frequencies eliminated. My attachment point will be after my H. Something similar to these pictures I found.

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Thought of that and it appears that is not how it works, but from others they say that once you get them on it covers a small section of frequencies and most have said they dont notice the others. In other words, shoot for the middle, 135 for you.

Ordered the stainless summit racing jpipes and taking them over to be welded in on Monday! Targeting 25in for length

I have the Thermal R&D axle back system on my 2018 and I LOVE IT.

Super throaty, absolutely no drone whatsover, relatively quiet at light throttle, but will raise the hair on the back of your neck when it's rippin' time. I have gotten dozens of comments on the sound.

Very high qualitly system to boot.

If I had to do it all over again, I would not heistate to get this exact same Hemholtz equipped exhaust system.

schmeky said:

I have the Thermal R&D axle back system on my 2018 and I LOVE IT.

Super throaty, absolutely no drone whatsover, relatively quiet at light throttle, but will raise the hair on the back of your neck when it's rippin' time. I have gotten dozens of comments on the sound.

Very high qualitly system to boot.

If I had to do it all over again, I would not heistate to get this exact same Hemholtz equipped exhaust system.

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I love love the price on the system for their full catback
https://thermalrd.com/products/2015...m-gt-50-years-limited-edition-catback-exhaust

But I'd be worried about overall volume with no mufflers.

I don't see an axle-back only option....

Just got my jpipes welded in on stock exhaust. drone is gone. 100% happy. 25" length.

lkeltner said:

I love love the price on the system for their full catback
https://thermalrd.com/products/2015...m-gt-50-years-limited-edition-catback-exhaust

But I'd be worried about overall volume with no mufflers.

I don't see an axle-back only option....

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I’m definitely intrigued by this system. The resonator is what they call “straight through” which probably means it’s a packed core like magnaflow. That and the helmholtz chambers are actually mufflers. The packed core is an absorptive muffler that only attenuates high frequency. The Helmholtz chamber reactively attenuates one specific low frequency band. I just don’t know if the band is wide enough to catch everything the absorptive muffler misses. Some f-150 mufflers are actually a trio of helmholtz chambers of different sizes to hit different bands, and they let very little through.

engineermike said:

I’m definitely intrigued by this system

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Thermal R&D has been private labeling systems for some time. Krona Performance is one,
https://www.kronaperformance.com/product-page/2018-s550-mustang-gt-fastback-3-catback-exhaust-system

The Thermal R&D resonator isn’t packed but it is chambered……..Thermal referred to it as their “Mixing Chamber”
IMO this is reminiscent of the MAC ProChamber from the Windsor days.
Not ideal for high CFM exhaust.