Stop the Drone - Helmholtz Style

[Hicompression]

Originally Posted by zepcom

The proof of my claim of "high pressure area J-pipes" is that even after an hour of driving a J-pipe enabled car, the j-pipes themselves will be cool to the touch. This is because sound waves (only) are what enter and exit from the J-pipes, not exhaust gasses, and sound waves are independant of heat. Exhaust gasses, in contrast, contain a lot of heat, as the byproduct of the combustion process. Thus, be careful doing this test, as if you were to touch a part of the exhaust system that is NOT the J-pipe section after an hour of driving, you'd most definitely burn yourself. Don't say I didn't warn you!

Wrong. The J-Pipe is just as hot as the rest of the exhaust due to conduction of heat through the metal of the exhaust system. Exhaust may not be actively flowing through the J-pipe, but it is still conducting heat. I wouldn't be touching ANY part of the J-pipes after an hour of driving.

[zepcom]

Originally Posted by Hicompression

Wrong. The J-Pipe is just as hot as the rest of the exhaust due to conduction of heat through the metal of the exhaust system. Exhaust may not be actively flowing through the J-pipe, but it is still conducting heat. I wouldn't be touching ANY part of the J-pipes after an hour of driving.

Wow. Have you tested this with a thermometer or are you just guessing?

My j-pipes are cold to the touch at any point along the j-pipes except where it is close to the exhaust pipe itself (which yes, would be warm by the stainless getting hot 'near' the J-pipes and transferring said heat those few inches)

Next time, you may want to do a little more research before calling me out, pal.

[BigRed585Lbs]

Russell, according to Solo, there's no need for a j-pipe on their V8 systems, and they should know. See this link (won't tell you to use the "search" function!):
http://www.camaro5.com/forums/showth...lo+performance

Something further: the j-pipe needs to be connected on the side of the exhaust pipe AWAY from the exhaust flow to prevent turbulence, and can be of as large a diameter as convenient, as a larger diameter will give more attenuation of the drone frequency.

I'm not a drum-beating fanboy for Solo; just stating some facts.

[ssmike]

zepcom, nice info, thanks, it all makes sense! The Solo cat back for the Camaro does not drone, but add a set of high flow cats and now your talking drone! The Camaro has the same rpm range of drone as the G8 1700-2000rpm. So I would think there would be a big market for these not only for my setup but anyone with high flows/headers and cat back combos that drone, both 2 1/2" and 3" systems.

[Hicompression]

Originally Posted by zepcom

Wow. Have you tested this with a thermometer or are you just guessing?

My j-pipes are cold to the touch at any point along the j-pipes except where it is close to the exhaust pipe itself (which yes, would be warm by the stainless getting hot 'near' the J-pipes and transferring said heat those few inches)

Next time, you may want to do a little more research before calling me out, pal.

The tips of the metal hangers on the stock exhaust have burnt me. How much exhaust does a hanger flow? Simple laws of heat conduction. You may have your J-pipes oriented to where they are in a high area of air-flow under the car. Convection may be cooling them down. To tell someone to grab a J-Pipe after an hour of driving while not knowing the orientation of their pipe is just flat out irresponsible.

[Russell James]

I'd like some solution for an - LT, high flow cats, X & full catback. ARH full system. Drones like a mother in 6th gear between 70 and 80. Incredible sounding in every other way, but 6th gear on the highway below 80 is hmmmmmmmmm.

[BigRed585Lbs]

Talk to Steve at Solo Performance. Those are some "drone-killing" folks!
Steve Mariano, 516-655-9002, goingsolo2@hotmail.com,
http://www.solo-performance.com

[Roger Ramjet]

Originally Posted by zepcom

Unbalanced (as it pertains to the G8 offerings) means that there is no "connecting pipe" in front of the mid-muffler... meaning each separate bank of the car (side of the engine, consisting of 4 cylinders each) has it's own respective 'pulse' that goes through the muffler in an offset pattern............ Anyways, at part throttle and idle conditions, these pulses are slightly noticable and are music to my ears. I do describe it as a "lope" similar to a mild cam sound would have. Slightly uneven offset of sound but not "misfire" or other bad issues. I compare to the dukes of hazard sound, if you've heard that, you have heard an offset or unbalanced exhaust system.

I know 'good' exhaust sounds are subjective. I tried 2 independent pipes as my 3rd A6 car system. (The J-pipes are the 6th exhaust mod.) I didn't like the blaa, blaa, blaa slow rhythm it had. I put a H-pipe in front of the mid mufflers and got a much faster ripping V8 sound.

[Roger Ramjet]

Any muffler shop should be able to do these J-pipes. I used 2.25 inch mandrel bent 180 degree U-tube. Needed 3 U-tubes; 1 left, 1 right, and cut the 3rd in half to make 2 90 degree bends into the muffler. I added straight pipe as necessary to tuck into the cavity and achieve the 28 inch total length.

[zepcom]

Originally Posted by Hicompression

The tips of the metal hangers on the stock exhaust have burnt me. How much exhaust does a hanger flow? Simple laws of heat conduction. You may have your J-pipes oriented to where they are in a high area of air-flow under the car. Convection may be cooling them down. To tell someone to grab a J-Pipe after an hour of driving while not knowing the orientation of their pipe is just flat out irresponsible.

I was simply explaining that since the J pipes themselves target the soundwaves only, they will not be as hot as the other exhaust components, including the exhaust pipes and hangers that are solid stainless and directly connected to the hot flowing exhaust.

It doesn't take a rocket appliance to carefully test something for heat. You can use one of those "point and shoot" infrared thermometers, they're like $15 at the parts stores.

I just tested my exhaust today in the Northeast USA after a 25 mile commute home. I touched about 2 inches away from the capped end of the j-pipes, and they were not hot at all. I could hold on for 15 minutes if I wanted to.

Likewise, I would never grab anything (nor would I recommend you or anyone reading this) that has direct contact or is directly part of the exhaust system. Since you burned yourself on the hot exhaust hangers, that's what was irresponsible, not me making a point that the hot exhaust gasses never enter the J-pipes.

Perhaps if you would have J-pipes in the middle east you could test this theory instead of again trying to guess. I've done it several times with teh same results each time. It doesn't matter anyways, since perhaps in the middle east, it's like 125 degrees ambient temperature, and touching the paint on your hood would burn you. I don't know; I've never been to DFDubya. But to that end, I don't pretend that I know and make a fool out of myself trying to "tell you like it is".

Good day to you, sir. Be careful when working under your own car. Do so at your own risk. This includes touching exhaust hangers too.

I was trying to contribute and help explain J-pipes to people who didn't understand them. I don't see you contributing anything 'useful', mr. hi compression.

[BigRed585Lbs]

If anyone cares to pursue this idea further:
http://www.g8board.com/forums/showthread.php?t=16077
http://forum.grrrr8.net/showthread.php?t=10801

[Nutbutt]

ZEPCOM is correct, the J-pipes adjust-ability is at the end of the j-pipe. The temperature at the caps cannot burn you even after hours worth of driving. I know I love to change the cap length just to experiment with the sound changes. It is a science in getting the overall length right the first time.
Great write up ZEPCOM !

[BigRed585Lbs]

Here's a video/sound blast of the best-sounding G8 with j-pipes (at that time) I EVER heard. Rather listen to this than hear a pretty girl sing!

[BigRed585Lbs]

Here's an iphone app for figuring out what your drone peaks at.
http://www.faberacoustical.com/produ...e/signalscope/