35 replies to this topic

[Sybil]

Put the cats back on. Drone is awful on a Viper too with no cats.

[CaptRon]

Ok stupid question. I assume a J pipe is shaped like a J.

where is it located in the exhaust layout? Anyone got picks of their exhaust with the J pipe?

[Ed_R]

I have this setup with a Borla ATAK. I like it fine. It drones. I don't care.

5.7 + SRT8 Headers + Solo High Flow + SRT8 Flowmaster American Thunder (muffs only/no resonators).

 

Deep Tone with no drone!

 

I luvs!

 

Stevo

[Renfrick1]

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There on the rear just before the tail pipes

[Renfrick1]

Try this one

[CaptRon]

Try this one

Ok now I'm real confused?!?!?

So now we have this pipe that loops back under the car. Is it open on the end thus blowing exhaust under the car or is the end capped off.

Either way how does this reduce or eliminate drone?

[Daddy Kool]

First off, I'd never put all that pipe under my car for a "cool" sound.  I think it looks similar to the plumbing remedy for water hammering.

[Renfrick1]

The j pipes are capped
They are similar to a trombone
The engine releases four different frequency that produce the drone. The j pipes cancel those frequency's
They tuck up under the rear quarters and you can't see them. Only if your lookin for them

[CaptRon]

The j pipes are capped
They are similar to a trombone
The engine releases four different frequency that produce the drone. The j pipes cancel those frequency's
They tuck up under the rear quarters and you can't see them. Only if your lookin for them

hmmm, sounds plausible. That's where I was gonna put my Dynomax mufflers. Guess I need to do some rethinking for my frankenexhaust!!!!

[Renfrick1]

Believe it or not they work. The funny thing is that no exhaust gasses go in the j pipes and are stone cold to the touch. The caps are adjustable in length to adjust for certain mods. Whether it's s/c heads cam or just certain cai. Where they set them stock is usually the right length

[NTMID8R-R/T]

hmmm, sounds plausible. That's where I was gonna put my Dynomax mufflers. Guess I need to do some rethinking for my frankenexhaust!!!!

 

 

well you been to Challengerfest, and many of us there have the solo system....so this year, take a look under some of our cars, as I too have the solo system, and Love it!!

[CaptRon]

Believe it or not they work. The funny thing is that no exhaust gasses go in the j pipes and are stone cold to the touch. The caps are adjustable in length to adjust for certain mods. Whether it's s/c heads cam or just certain cai. Where they set them stock is usually the right length

How are the caps adjustable?

I'm guessing no one sells just a J pipe to weld to a current system?

Found some info on another forum about how to set the length of the pipe and the science behind it.

See below:

 

 

Basically drone is an unwanted frequency in our exhaust note that we dont want to be there. Since we cannot remove it we have to cancel it out. The J pipe is a helmholtz resonator used to do just that. Take a close look at your factory intake system and you will find one or two. Ever wonder why the cai makes that cool sound that the oem one doesnt?!

Ok application. You can use a computer listening app (frequency analyzer) or a vibration analyzer (I used the one over at the GM shop at work) to find your drone frequency. It is usually between 1400-2000 rpm cruising in 6th gear when afm is not engaged. The hz value varies but it is usually from 90-120hz. Mine was about 110hz and could rattle change in my cupholders. ;(

Now what do you do with your frequency number? Use math!! Wanna sound super smart? We will be using the speed of sound as a factor in this equation
go brag to all your friends.

Simply put, the formula for determining the length of a Helmholtz chamber used to knock out a drone frequency is:

1100 feet/second (roughly the speed of sound) divided by the target frequency you're trying to eliminate (in cycles/second) gives a full wavelength in feet per cycle. Divide this number by 4 to get a quarter wavelength (a much more convenient length to work with). Finally, multiply this wavelength by 12 to get the chamber length in inches.

So with my 110hz value it looks like this ( 1100 / 110hz ) / 4 ) x 12 = 30 inches

So the length of the helmholtz chamber needed for killing 110hz drone is 30". Now this will kill drone in a range slightly above and below 110 which is good so you dont have to have like 5 different chambers to clean out the drone.

How does it work?? Well basically the J is capped on the end and should be installed so it is out of the flow of the exhaust stream. We only want sound going in the chamber and when I does it travels all the way to the end and bounces back. When the sound bounces off the sealed end of the chamber it comes back 180* out of phase from the original sound and calcels it out voila!! A simpler example might be hooking up two subwoofers in a car and hooking up one out of phase from the other. Theres no bass right?! Same principle.

So here are some pics of how I built mine and mounted them and also a few threads with some additional info that I used while in the design process.

Dynomax 41221 with a big filled in fender washer on the end. Ready to install. Note that the pipe can be any shape that fits not necessarily a J.



Holes cut for install. They can be slightly smaller than the pipe. Flow is not important here.

 

After welding them on



And DONE!! Go take a test drive. Your wife or girlfriend is sure to notice!!





Not sure you want to take the leap just yet? Here is some more info

http://www.performancecarweb.com/showthread.php?t=144

http://www.g8board.com/forums/showthread.php?t=16077

 

You need to place the pipes so that the don't receive direct exhaust flow otherwise they will create a restriction in the exh system. The sound waves will go into all areas of the exhaust and are not limited by the properties of airflow. More sound attenuation can be achieved with a larger pipe diameter. For example: I used a 2" J pipe on my 2.5" system. A 2.5" j pipe on my 2.5" system would kill more drone but I didn't want it to be totally quiet either

More technical info on the Hemholtz resonator.

http://www.rexresear...zresonators.htm

[CaptRon]

More from another forum:

 

 

 

Helmholtz Pipes in a nutshell:

As others above have said, with a sampling of soundwaves similar to the above, and the proper mathematical formula you can calculate the ideal-length of your "J-pipe".

The J-pipe itself is sealed, it's piping is generally cool to the touch even after the other parts of the exhaust system are scalding hot. Since it's sealed, it's a high pressure area, and no exhaust gasses have anywhere to exit out of it, so they don't try to enter it.

Soundwaves, on the other hand, travel through anything they can. Drone is an unpleasant sound wave, actually.

So with the formula calculated, and the J-pipe of the correct length, soundwaves enter the mouth of the J-pipe in a soundwave pattern. Remember back to math class: sin and cosin ? Picture that, for this example. So sound waves of a specific frequency (drone) enter the J-pipe, and hit the "capped, sealed, end" and reflect back in the EXACT OPPOSITE SOUNDWAVE PATTERN ... mathematically, if you have a sin and the inverse of it, it turns into a flat line. Similarly, the "reflected back" sound cancels out all the new soundwaves that have since been produced and are trying to enter the mouth of the J-pipe chamber once again.

Result? SILENCE.


This does not take away from the great sounds of performance exhaust (or SOLO Exhaust systems, in my case). It targets the drone soundwave (in Hertz) and cancels it out, leaving a drone free experience in the cabin of the car. Pure musclecar aftermarket performance exhaust sound, without any of the headache-inducing drone. What's not to love?





SOLO's J-pipes also have clamps on the "tuba section" so that as time goes on and your mods change, the frequency of the drone your car produces may slightly vary. Lets say you add headers and now have a slight drone. Simply slide under the rear of the car with a socket wrench, and adjust the J-pipes according to the manufacturers recommendations, and you can now target the new frequency (making the J-pipes longer or shorter changes the target frequency that gets canceled out!) and you're once again "Drone Free". Amazing!!
 

This image has been resized. Click this bar to view the full image. The original image is sized 1024x768.

This image has been resized. Click this bar to view the full image. The original image is sized 1024x768.


Since the success of the SOLO J-pipes on their 5 catback kits and 1 axleback kit for the G8, SOLO went forward and created one of the first drone-free kits for the "hard to modify with aftermarket exhaust" V6 Camaro with the DI 3.6L engine. They also released J-pipe kits for the V8 Camaros as well.


I'm fascinated by the J-pipe technology and was amazed to be so successful at helping to fix a product for the entire g8 community to enjoy. As a result, my participation at g8board.com grew substantially, and they made me a Moderator there since I had been helping everyone out so much. Giving back to the G8 community is what I'm all about.

This PCW site is the next "wave" (pun intended) ... so hang on, everyone, it's gonna be a great ride!! Look for more upcoming "how to's" and other useful information that I look forward to sharing with everyone on this new Performance Car Web forum. I'm really excited!!

I'm greatful for the knowledge and patience that BigRed585lbs had with me back in late 2009 when I took it upon myself to try this unconventional design. The rest is history!!!                                                                                                                                                                                                                                                              Parts used: Dynomax #42426 stainless steel j-bend 2" diameter, available from Jeg's or Summit, your choice. Cost about $22 ea. 2 required. Cut/fish-mouth the long leg to match the main pipe of the axleback. You also need two 2" diameter stainless steel fender washers (got mine at Lowe's) to cap off the end of the short leg of the j-pipe AFTER you weld up the hole in the center of the washer.

Cut a hole to size in the axleback and weld the open end of the capped j-pipe on to this hole. Tack the j-pipe wherever it touches the axleback to prevent vibration.

With a file or die grinder, clean up any protrusions to the inside of the axleback tube you may find, as well as the flange if the mating face of the flange is not flush. Makes tip adjustment easier. Any questions? There will be a pop-test at the end of this class.    

All it took was two 2" stainless steel j-bends from Jeg's (p/n #289-42426 @ $21.99 each) and a couple of 2" stainless Steel fender washers from Lowe's. Cut the pipe to 31", capped the short end, and tapped into the PM-FL's just like LSPowered65 showed. Horrendous drone was down to an acceptable level. And, at last, BigRed sounds as good as the '08 Mustang Bullitt I traded in for it.

Simply put, the formula for determining the length of a Helmholtz chamber used to knock out a drone frequency is:

1100 feet/second (roughly the speed of sound) divided by the target frequency you're trying to eliminate (in cycles/second) gives a full wavelength in feet per cycle. Divide this number by 4 to get a quarter wavelength (a much more convenient length to work with). Finally, multiply this wavelength by 12 to get the chamber length in inches.

Tap this length of pipe into the exhaust tube, making sure the other end of the pipe is capped off, and you have a Helmholtz chamber that takes the annoying frequency and bounces it back into the flow 180 degrees out of phase, knocking it out. The results: no more drone.

 

[Renfrick1]

The caps are adjustable by clamps. Loosen the clamp and slide the cap to the setting you want. Tighten the clamp

[Goehner]

http://modernmoparfo...64/#entry359721

[BADPLM]

Update...

 

Kept my JBA catless mids.  Put on my stock exhaust with the Corsa tips of course.

 

Love the lack of interior noise.  Wish it was just a little bit louder outside the car, but I will be sticking with this set up.