Flowmaster Drone on LS3

[PMJ]

I'm new to this forum/Camaro's in general. I just bought my 2012 SS LS3 less than 2 weeks back. I had a Flowmaster American Thunder 3" cat-back installed. I love the sound except on the highway when the drone kicks in at cruising speed (it goes away about 95mph ). The other solution of course is 5th gear.

I called around town (Houston, TX), and haven't found anyone who has actually installed the J-pipe/Helmholtz solution. Based on the Helmholtz chart, i would need a ~26" J-pipe...i'm not sure there is room under my car w/the American Thunder mufflers...the pictures on-line shows it with the Outlaw mufflers. Does the j-pipe solution quite the sound? Or simply tune out the drone?

One of the more knowledgable folks I talked to is recommending i install a Magnaflow dual 3" in/out muffler where the stock resonators used to be, of course that will quite it a bit, but he claims it will have no negative impact on performance.

I also have a CAI (from CAI inc) w/scoop coming in the mail. I've seen some post that imply the CAI may resolve the drone??? Doesn't make sense to me...should i wait to install my CAI prior to trying to resolve the drone?

Any expert recommendations? No need to recommend going back to the stock system. I want my cake and eat it too .

[wontsellit]

I'm so rarely in 6th it doesn't matter.Even then I like the sound just not for hundreds of miles. I have JBA hi flow cats,X pipe,resonator deleted and the flow masters.

[Synner]

Tone won't change with the j-pipe just remove the drone if the correct length. An intake won't do anything for drone.

I'm sure it's possible to fit under there but you may need a custom made solution versus a pre-bent kit someone sells. A resonated x-pipe will quiet it down some and maybe reduce drone a bit but I doubt it'll remove it. The drone comes from the 3" pipe size and a lower speed exhaust flow area that causes turbulence. Dynomax has mufflers with internal valves that remove drone although I'm not personally too keen on putting a big valve in my exhaust.

[SGOS252382]

Magnaflow resonated X pipe (looks like a muffler) will help.

I put a Flowmaster catback on my 99z28. That catback only lasted about 3 weeks on the car. I couldn't stand the drone at cruise speeds. Some don't mind it, while it drives some people crazy (like me).

[nighttowl]

Dronemaster.

[VR Baron]

The J pipes killed all the drone for me. The resonated x pipe, or another muffler, reduced the drone a little but killed the sound to much. One person on here did J pipes with the FM American thunder, just have to serach for it. Has pics, they go up and over the mufflers.

[1sikRS]

Anyone no why they used 40 series and not the 44s??/

[justa25thTA]

the j pipe will cancel the drone. get er done.

[PMJ]

Thank you all. I'm going to go with the j pipe. Now just need to find a place to do it. One more stupid question...is there something special about the "J". Or do I simply need any pipe around 26" +/- a few inches? I'm thinking an "L" may be easier to fit.

[BigRed585Lbs]

Here's a photo from post #242 on this topic showing Flowmaster AT's with j-pipes:
http://www.camaro5.com/forums/showth...102075&page=10



Hope this helps. I hate drone, too.

[PMJ]

Originally Posted by BigRed585Lbs

Here's a photo from post #242 on this topic showing Flowmaster AT's with j-pipes:
http://www.camaro5.com/forums/showth...102075&page=10
.

Thank you BigRed. The picture helps, but unfortunately it did not help the person who posted it. Which raises a few more questions I have as I'm trying to design my own solutions.

1. Size of the J-pipe (3" vs. smaller). In this picture they are using a much smaller size (but it didn't fixe the problem). Does the j-pipe need to match the 3" pipes?

I'm hoping his didn't work because he did not use 3" pipes to match his system, and it does not appear he used the Helmholtz chart...he was at 30", but complaining about 1800rpm drone (so i think he needs to shorten the j-pipes. I'm working on my own design, will post when i finish it for comments.

Here is the Helmholtz chart i'm refering to (i just realized the picture may have been on a V6...in which case the pipe is not long enough):


2. Can someone still clarify if the J-pipe needs to have a "J" at the end, or does it simply need to be the right length per the chart above? I'm planning to build a varible lenth pipe that can grow or shrink about 4". Looking to range between 25-29".

[VR Baron]

Originally Posted by PMJ

Thank you BigRed. The picture helps, but unfortunately it did not help the person who posted it. Which raises a few more questions I have as I'm trying to design my own solutions.

1. Size of the J-pipe (3" vs. smaller). In this picture they are using a much smaller size (but it didn't fixe the problem). Does the j-pipe need to match the 3" pipes?

I'm hoping his didn't work because he did not use 3" pipes to match his system, and it does not appear he used the Helmholtz chart...he was at 30", but complaining about 1800rpm drone (so i think he needs to shorten the j-pipes. I'm working on my own design, will post when i finish it for comments.

Here is the Helmholtz chart i'm refering to (i just realized the picture may have been on a V6...in which case the pipe is not long enough):


2. Can someone still clarify if the J-pipe needs to have a "J" at the end, or does it simply need to be the right length per the chart above? I'm planning to build a varible lenth pipe that can grow or shrink about 4". Looking to range between 25-29".

That pic is from was the person I was refering to. Do research on all theJ pipe threads, but I dont think the shape matters from what I recall reading. You want the shape to the same side to side, same length and welded at the same spot also.I'v seen pics of straight and S shapes also.
Mine are in the 28.5-29.5" range and drone is dead in the 1500 rpm on uo range. Also not exact science as someone said if you have say drone at 1800 and you make the pipes that long per the chart, it kills drone +-300-400 rpm, 1800 being the mid point.
For the Pipe size 2.25-2.5" is fine. I used 2.25" as the outlaws are 2.5" dia on the axelback.
I have the Outlaws and they are way louder then American thunder, I tried it all, resonated x pipe, insulation, only worked a little, the pipes did it.Now I also had the stock LS3 resnators which help(axelback setup)Without them Mine is like a 2.5" piped catback.For me it popped to much and overall a bit loud on the freeway, not bad but just over the top, for me anyway, wasnt drone, just good old exhaust sound.Again Mine is louder then yours so you should be o.k. Besides numerous people have full blown systems on their cars and the J pipes did the trick.

I figure give it a try, if not you may want to get a Solo catback.

Hope this helps

[ddunerider]

I must be crazy I dont hear drone.....

[Sleez]

shape doesn't matter, length is where it's at, ahem!!!

it's also a good idea to make an end cap that gives you a bit of adjustment, +- an inch or two. the diameter effects the volume of air mass, and effects the usefulness a bit.

"When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out. The cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.
The air in the port (the neck of the chamber) has mass. Since it is in motion, it possesses some momentum. A longer port would make for a larger mass, and vice-versa. The diameter of the port is related to the mass of air and the volume of the chamber. A port that is too small in area for the chamber volume will "choke" the flow while one that is too large in area for the chamber volume tends to reduce the momentum of the air in the port."

see more here; http://en.wikipedia.org/wiki/Helmholtz_resonance

[VR Baron]

Originally Posted by Sleez

shape doesn't matter, length is where it's at, ahem!!!

it's also a good idea to make an end cap that gives you a bit of adjustment, +- an inch or two. the diameter effects the volume of air mass, and effects the usefulness a bit.

"When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out. The cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.
The air in the port (the neck of the chamber) has mass. Since it is in motion, it possesses some momentum. A longer port would make for a larger mass, and vice-versa. The diameter of the port is related to the mass of air and the volume of the chamber. A port that is too small in area for the chamber volume will "choke" the flow while one that is too large in area for the chamber volume tends to reduce the momentum of the air in the port."

see more here; http://en.wikipedia.org/wiki/Helmholtz_resonance

There you go!

[BigRed585Lbs]

J-pipe shape is usually determined by what space you have available for them. Pipe diameter, in my case, was determined by what size and material tubing was available. You guys are right on with the theory you're using.

[VR Baron]

Originally Posted by ddunerider

I must be crazy I dont hear drone.....

True, you're crazy, we all know that

[PMJ]

I appreciate everyone's comments, i know this topic is covered frequenlty in this forum. 1 more question...

Has anyone successfully removed the drone from a Flowmaster American Thunder cat-back system on a LS3 using j-pipes? If so, can you post pictures?

I have found picture of successful Flowmaster Outlaw j-pips, and pictures of unsuccessful American Thunder...but yet to find a picture of a successful American Thunder j-pipe.

I'd like to make sure i have a chance of success before modifying my current system...the alternative of course to resell and go with Corsa or Solo...but i really like the American Thunder sounds...

[PMJ]

So it seems like i talked to everyone in town, and no one recommended J-pipes to fix my drone. I could not even get anyone to give me an estimate...they wouldn't even try on my dime. Finally I found a place that would give it a go...Christian and Wayne at a local Meineke Muffler on Jones Rd in Houston.

I think they thought I was crazy, but they were willing to humor me; so we started cutting and bending pipe to the specification of the Helmholtz chart...my drone was worst at 1900, so we built to 26.5" exact (see chart above).

Below i have the pictures of my j-pipe design and some install pics. We used 2.5" stainless steel pipe. I'm happy to say the drone is gone!

Christian and Wayne are now open for j-pipe business in the Houston area!
================================

Here is the J-Pipe i designed...we cut the pipe at 28.5", made the first bend ~65 degrees, and then cut 2" off the short side of the bend. The second bend is 90 degrees and at an angle to go around the muffler at an upward angle...



Muffler before:


In progress:


Final results:


Completely hidden from behind:

[Sleez]

very cool, good job, glad it worked, knew it would!!

[BigRed585Lbs]

And the beat goes on!

Let those who will cut and bend pipe have great sounding vehicles (this stuff works on anything with an exhaust and a drone problem).

Really glad it worked out for you and the muffler guys who were willing to try something "new" to them. Now they "know",too.

[Camaro_h]

Changed my American Thunder cus of the drone and got me CORSA. Wish you had this info up before hand lol

[VR Baron]

Glad it worked. Your experiance with people looking at you as if your crazy is probably normal, most dont know about J pipes though GM uses them on our car's and others for years. I love my outlaws now, at a show yesterday two members and a new guy heard mine and want to switch from super 40's to the outlaw!

[v6sonoma]

I'm glad it worked for you. You'd think Flowmaster would just start selling them like that since it's such a problem.

[Camaro_h]

Flowmaster's intension is to have the DRONE! lol otherwise you have other alternative exhaust systems