Multiple J-Pipes

[brettsimons]

Originally Posted by VR Baron

Mine are Adjustable. I just went with the recommended length to kill the drone in the rpm range I had it in. Remember if the table that has been posted up says x length for say 1800 rpm drone, it is +- 3-400 rpm of that also, or really a mid point rpm.I had drone from 1500 to 2400 with the outlaws, set it for the 1800-1900 range and the drone is gone in the entire range I had issues with.

Wow that's awesome! I'm excited to finally get it done and not have to try and avoid the highway anymore

[J-ROD-210]

Has anyone done before and after dyno's of J-pipes? I'm wondering if using exhaust backing up into itself to kill drone is a good thing.http://www.youtube.com/watch?feature...&v=n8VlynaUVO8

[brettsimons]

Originally Posted by J-ROD-210

Has anyone done before and after dyno's of J-pipes? I'm wondering if using exhaust backing up into itself to kill drone is a good thing.http://www.youtube.com/watch?feature...&v=n8VlynaUVO8

Well from what I've read and my general physics knowledge because it is at a 90 degree angle, the exhaust will either not back up into it or the exhaust will fill the tube until it is at an equal pressure with the pressure inside the rest of the pipe taking less than a second and then once the pressures are equal, no more exhaust will flow in or out of the J-Pipe but the sound will continue entering the tube since it isn't effected by the exhaust's pressure. The sound will travel down the j-pipe and bounce back from the capped end re-entering the main exhaust system at a delayed time effectively canceling out the specific and surrounding hertz at which the drone is occurring.

I'm looking for some good youtube videos now in case anyone wanted to learn about the physics behind it

Edit:
1. This is the basics of sound cancelling http://youtu.be/mDS5r5t0VS0?t=16s. When the sound waves being "out of phase" is the same effect as the delay we are experiencing in which the delay caused by a perfectly calculated tube would cause the sound wave to become "180 degrees out of phase" and therefore completely cancel out the drone but of course we don't live in a perfect world :(

2. I couldn't find a good video but basically the high pressure of the exhaust tube will flow into the lower pressure area of the J-Pipe until the pressures are equal and once that happens nothing flows in or out just like if you were to fill the pipe with water and watch it flow, the water in the J-Pipe would be stagnant while the other water continues to flow. This is all theoretical and only applies in a perfect world so you will get some flow where the two pipes come together but not enough to matter.

[brettsimons]

Originally Posted by J-ROD-210

Has anyone done before and after dyno's of J-pipes? I'm wondering if using exhaust backing up into itself to kill drone is a good thing.http://www.youtube.com/watch?feature...&v=n8VlynaUVO8

Just watched that video and having a little back up will give you a little better low end torque but of course your horsepower will suffer a little bit from it since horsepower is a function of torque and therefore the more torque the less horsepower and vice versa!

[BigRed585Lbs]

JMO

The common view is that catback and axleback systems do little to boost horsepower. You have to go to long tube headers and high-flow cats before you realize any power gains.

I don't know if this is true, but I do know that any horsepower gains are not worth much if you don't enjoy driving your car. And a sweet-sounding exhaust will make a car guy/gal want to drive, drive, drive!

Come on, warm weather!!!!

[brettsimons]

Originally Posted by BigRed585Lbs

JMO

The common view is that catback and axleback systems do little to boost horsepower. You have to go to long tube headers and high-flow cats before you realize any power gains.

I don't know if this is true, but I do know that any horsepower gains are not worth much if you don't enjoy driving your car. And a sweet-sounding exhaust will make a car guy/gal want to drive, drive, drive!

Come on, warm weather!!!!

Amen to that! Headers and exhaust are the best purchase I've made besides the car lol

Sent from my Galaxy Nexus using Tapatalk 2

[VR Baron]

I didnt notice any hp loss as it would have to be minimal. Cut open a stock muffler and you will see a J pipe

[BigRed585Lbs]

This one's a V8 muffler:



Here's the V6 one:



J's all the way! Something has to kill that drone.

[brettsimons]

Well after only having time to install one J-Pipe on Saturday, I took the car out and wow does it make a difference! The drone was already half of the way gone so when I went to make the second one, I made it 29.6 inches to get the drone at 1700 as well as the one already on the other pipe for 1900. So now my car is quite on the inside until I floor it and get into the upper RPMs. All I can say are J-Pipes work miracles and I can't believe how well they work!

[VR Baron]

Originally Posted by brettsimons

Well after only having time to install one J-Pipe on Saturday, I took the car out and wow does it make a difference! The drone was already half of the way gone so when I went to make the second one, I made it 29.6 inches to get the drone at 1700 as well as the one already on the other pipe for 1900. So now my car is quite on the inside until I floor it and get into the upper RPMs. All I can say are J-Pipes work miracles and I can't believe how well they work!

Glad it worked out. When I did mine it basically moved the drone from inside to a "louder exhaust sound" out back but nice and doesnt bug you.

[brettsimons]

Originally Posted by VR Baron

Glad it worked out. When I did mine it basically moved the drone from inside to a "louder exhaust sound" out back but nice and doesnt bug you.

Well it sounds the same outside! Now I just don't have to hear the super loud drone that I had! But I ended up doing two different sized j pipes as apposed to two different sized pairs after hearing how well one did on its own!

Sent from my Galaxy Nexus using Tapatalk 2

[BigRed585Lbs]

Congrats on trying a new twist on the j's. So two slightly different lengths can deal with a wider freq range. Well done!