How to get rid of drone?

Sierra3

Sierra3

New member
Bought a 12468 magnaflow 2 in 2 out 2.5 inches. Its the center mounted muffler with X over built into it. It has some core built in, but to run just that off my headers and into the two SS dual pipes sounds horrible. Great when you punch it, but way too loud. Going to put the two magnaflow muffs back onto the tips. Don't want to, but im not leaving it like this. Horrible drone when pops into 4th gear overdrive.

I'll go with adding two high flow magnaflow cats first, then try two mini resonators at the tips in the rear.

The ideal sound I was going for/want was a factory 2001 SVT Cobra Mustang. Since that's my engine. Love the sound of those cars. They had center mounted muffler too, but also CATS into dual exhaust then into the tips. Want the same thing.

Any suggestions?
 
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racecougar

racecougar

New member
Sierra3 said:
I'll go with adding two high flow magnaflow cats first...
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That alone will make a noticeable improvement, IMO. My setup consists of the 1-3/4" Kooks into 3" downtubes, 3" Magnaflow cats, the 12468 muffler, expanding back out to 3" pipes after passing through the fuel tank area. I plan to redo the system in the future simply to improve appearance, but I have no plans to change the basic design (3" cats and a mid-mounted Magnaflow X-over muffler).





Here are links to a few videos if you want to get an idea of what it sounds like.

http://s6.beta.photobucket.com/user/racecougar/media/90 XR7/Gateway/10-31-12/P1140620.mp4.html
http://s6.beta.photobucket.com/user/racecougar/media/Run4.mp4.html
http://s6.beta.photobucket.com/user...Rods and Handlebars 2011/CougBurnout.mp4.html
http://s6.beta.photobucket.com/user/racecougar/media/90 XR7/DynoRuns5-20-10.mp4.html
 
budpytko

budpytko

Super Senior Associate
First thing I thought of for an answer when I saw the title of the post was - SHOOT IT DOWN!
 
driller

driller

El Presidente
The cats will make all the difference, but I bet it never sounds like a Cobra due to the difference in length.
 
Sierra3

Sierra3

New member
Thanks guys for the info!

budpytko said:
First thing I thought of for an answer when I saw the title of the post was - SHOOT IT DOWN!
Click to expand...
hahahha Awesome. "Yeah I got this annoying little one that keeps terrorizing my dog at night in back yard after dinner....hahahha It wont go away"... "We don't need no stinkin shotguns to drop the drones, we got EMP".

Wow, awesome links everyone!. Just got done reading the thing and posts all about the J pipe. I agree with that theory 100 percent. Matter of fact, look at our air intake violin cases and airbox that most have removed on this site. That was purpousely designed for exactly that same reason im guessing. other than to have an extra air pocket of hot air already under vacuum ready to go fast down the throttle body.

Nice videos Cougar!. Your cougar is damn quick man even without seeing the times at the end.

I was leaning more towards putting the cats back on simply for DOT Nazis and new money grabbing legislation to enable more heat to the hotrodders pocketbooks in form of tickets.. Its getting worse.

I have basicly the same setup exactly as your pic up on the lift. Except with ART longtube headers going into that 2X2 Magnaflow with X over built in. Sounds about the same too in videos but a lot louder. ( to be honest it actually sounded a lot better with open headers. ) haha But never could go down the road like that with a straight face, id get shot. hahah
Trying to get rid of the raspyness and also the drone that seems to only bother me while under load very light acceleration in 4th gear around 2000RPM 35MPH-50MPH, in town cruising speed. If I drive around with overdrive button off in 3rd, its sounds nice and mean. But when it pops into 4 overdrive it is like driving your old IROC Z or 88 Trans AM with those cheap ass cat back systems they used to sell. Its not tight and growly like the stangs, its more like diareha of low base farting. haha Can't describe it.

Im really intrigued about the J pipe. That is sound phisics right there and worth the shot at doing. We definitely have the room to pull it off back there with no muffs. I think ill add the CATs to get back legal, and then order some more mandrels and fab up some J pipes 2.5 inch and have cousin weld them in for me. Wow, this could be the solution.
Thanks for all your responses guys. Ill try to post a video up on one of the sites and sneak a link in here. Ill have to email utube again to find out what my old password was and do it there if possible. Seems to work a lot better than photo bucket anymore. I hardly use that now.
 
Sierra3

Sierra3

New member
driller said:
The cats will make all the difference, but I bet it never sounds like a Cobra due to the difference in length.
Click to expand...
True, was thinkin same thing too. But im sure we can get it close. never knew or thought about the J pipes. Those got to work, and worth getting some more mandrel sent out to me. Im on it after work tomorrow, be on the phone again. lol
 
9

97MarkJA

New member
I've seen the "j pipe" point in just about every direction, I should say any direction you have room to put it.
If you are unsure about the length you can weld a 13" pipe in place and use a piece that will slip over the other that is 16" long and capped on the end. Adjust the length until you kill the sound in the RPM range you want and weld it up.
The math is sound and will get you close to the correct length, some variables like temp and load will change the frequency a bit. The method works 100% of the time.
 
claude

claude

LSCULATER
I am at this stage of my build...exhaust! From Kooks Back. I am in a time crunch as I have to move from Florida back to North Carolina. As I too found a lot of good information on this Post. I have read nothing on the back pressure for the replies that have the "B" heads. I know johnboy is running a 2001 4.6 and don't think its as critical for the "C" heads. As $$ are a factor (current job to new job blues when moving), I will not be putting cats back on and going with x pipe and a more restrictive Magnaflow for the rear two mufflers for have more low end torque. Any ideas...part numbers? If the drone or noise is not right there will be a 2.0 in the future but have to get it on the road by the end of the month.
 
racecougar

racecougar

New member
claude said:
I have read nothing on the back pressure for the replies that have the "B" heads. I know johnboy is running a 2001 4.6 and don't think its as critical for the "C" heads. As $$ are a factor (current job to new job blues when moving), I will not be putting cats back on and going with x pipe and a more restrictive Magnaflow for the rear two mufflers for have more low end torque.
Click to expand...
Exhaust backpressure will always hinder performance on a 4-stroke ICE. However, bigger isn't always better in terms of exhaust tube sizing. When the size of the exhaust system more than exceeds the airflow requirements of the engine, exhaust velocity suffers and you start losing the benefits of exhaust scavenging. Here is a good article that describes just how beneficial a tuned exhaust system is:

Auto Exhaust Science

Here's another good link:

http://www.veryuseful.com/mustang/tech/engine/exhaustScavenging.pdf
 
claude

claude

LSCULATER
Awesome article! I'm half way through it, trying to digest all of it before making a decision! They don't teach this on OEM world!
 
Sierra3

Sierra3

New member
Check in back in here on this old thread. Yep. Killer articles and write-ups for sure. Thanks racecougar. It made me rethink my rear setup once I get car back. Definitely going with some of those J pipes with capped ends. I ordered some more mandrels, but left off the tips trying to find the factory look alikes I used to have. The oval ones. I think dynomax made them back in the day. They were oval, chrome, and were about same size as factory LSC cutouts in the plastic. Looked factory. Cant find them. My old muffler shop used to carry them, but not anymore. Now all you can get there is those garbage can sized Deisel tips or the wacky fast n furious setups.
 
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