Installed X Pipe = Instant DRONE
#1
Installed X Pipe = Instant DRONE
So I have a 2.5 inch mostly mandrel-bent true dual custom exhaust system on my 5.4L supercharged 2V truck. Stainless JBA shorty headers into a pair of Catco 2200 series high flow cats, through the piping and into a Magnaflow DIDO 11379 4x9 oval 11" body muffler.
At the time of the install a couple of years ago, my exhaust guy's Magnaflow catalog incorrectly indicated that the 11379 muffler had a perforated Tru-X core. In other words there was an X pipe built into it. Well I found out that's not true, as the 11379 11" body muffler is actually two straight through pipes. Only the 14" and 22" mufflers contain the Tru-X core in the DIDO configuration. So I have basically been running divorced true dual pipes with no crossover.
Fast forward to last friday, where I had my exhaust guy install what was supposed to be a Magnaflow 10791 2.5" Tru-X X pipe crossover into my existing system. He spliced it in, rebent one of the pipes to fit, and repainted the pipes black. He said the X pipe might make it a little quieter, and reduce interior drone a bit.
Previous to the X pipe install with the divorced duals, it had a nice aggressive exhaust note but an extremely tolerable level of interior drone. Adding the X pipe to the system alone, it has a louder idle, a less aggressive/more muddy exhaust note, and 3X the interior drone! Holy crap is the drone unbearable. It buzzes through the interior right after take-off, and gets extremely bad in the 1600-1900 RPM range.
What gives here, seems like it works fine for everybody but me? I'm gonna have to have it remodified again and go with an H pipe instead. I thought X pipes were supposed to help reduce drone. And correct me if i'm wrong, but the X pipe he installed doesn't look like no Magnaflow Tru-X to me.
At the time of the install a couple of years ago, my exhaust guy's Magnaflow catalog incorrectly indicated that the 11379 muffler had a perforated Tru-X core. In other words there was an X pipe built into it. Well I found out that's not true, as the 11379 11" body muffler is actually two straight through pipes. Only the 14" and 22" mufflers contain the Tru-X core in the DIDO configuration. So I have basically been running divorced true dual pipes with no crossover.
Fast forward to last friday, where I had my exhaust guy install what was supposed to be a Magnaflow 10791 2.5" Tru-X X pipe crossover into my existing system. He spliced it in, rebent one of the pipes to fit, and repainted the pipes black. He said the X pipe might make it a little quieter, and reduce interior drone a bit.
Previous to the X pipe install with the divorced duals, it had a nice aggressive exhaust note but an extremely tolerable level of interior drone. Adding the X pipe to the system alone, it has a louder idle, a less aggressive/more muddy exhaust note, and 3X the interior drone! Holy crap is the drone unbearable. It buzzes through the interior right after take-off, and gets extremely bad in the 1600-1900 RPM range.
What gives here, seems like it works fine for everybody but me? I'm gonna have to have it remodified again and go with an H pipe instead. I thought X pipes were supposed to help reduce drone. And correct me if i'm wrong, but the X pipe he installed doesn't look like no Magnaflow Tru-X to me.
#3
The X pipe he installed doesn't look like a Magnaflow unit. Notice how it's square-shaped in the center. The Magnaflow Tru-X has defined pipe shapes that intersect at the center to truly look like a X.
I had a Ebay special X pipe that looks similar to the one I just got installed. It had the square shaped center and also droned like a mother. It seems like that square open chamber would promote drone in the same way a hollow open chamber Flowmaster muffler would. And I think it has become way worse in my case since this X pipe is sitting right under the cab of the truck. Without the X pipe it was quiet when you needed it, and loud when you wanted it. Thoughts on my theory?
Here's what a Tru-X looks like (i'm sure you already know)
I had a Ebay special X pipe that looks similar to the one I just got installed. It had the square shaped center and also droned like a mother. It seems like that square open chamber would promote drone in the same way a hollow open chamber Flowmaster muffler would. And I think it has become way worse in my case since this X pipe is sitting right under the cab of the truck. Without the X pipe it was quiet when you needed it, and loud when you wanted it. Thoughts on my theory?
Here's what a Tru-X looks like (i'm sure you already know)
#5
Join Date: Jun 2002
Location: Under the flightpath of old ORD 22R
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It was not S/C, but my 2001 5.4L NA Screw I installed the Lightning Bassani Dual system on, with the X pipe. Had to cut the factory Y out and change to a system that looked more like the L / HD system with the dump in front of the rear wheel. The Bassani X pipe was more defined in the round X look, rather than a stamped box look to it.
The Bassani X pipe with 2 SI/SO mufflers did not cause cab drone. It was loud at WOT, but at cruising it was mellow.
The Bassani X pipe with 2 SI/SO mufflers did not cause cab drone. It was loud at WOT, but at cruising it was mellow.
#6
Thanks for the input fellas, keep it coming if you could. I'm leaning towards changing the setup to a H-pipe.
Here's the before/after X-pipe videos if you want to hear the difference the X-pipe alone makes. Watch with headphones for best quality.
Before
http://www.youtube.com/watch?v=CFUi3...&feature=g-upl
After
http://www.youtube.com/watch?v=ZjxyO...&feature=g-upl
Here's the before/after X-pipe videos if you want to hear the difference the X-pipe alone makes. Watch with headphones for best quality.
Before
http://www.youtube.com/watch?v=CFUi3...&feature=g-upl
After
http://www.youtube.com/watch?v=ZjxyO...&feature=g-upl
#7
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#8
Join Date: Jun 2002
Location: Under the flightpath of old ORD 22R
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From what I recall, the H pipe did not add anything with the scavenging effect, it was only an equalizer.
The other thing, the '03 and older L and the HD had the X pipe right at the front of the dual SI/SO mufflers.
The kit in the picture above is installed as it would be on a L or HD, and the additional pipe is added to the front ( had I got a HD version, the pipe would have been in the kit ).
Don't know if this still holds true on a S/C 5.5L 3V motor or not, just know what I had found out before.
The other thing, the '03 and older L and the HD had the X pipe right at the front of the dual SI/SO mufflers.
The kit in the picture above is installed as it would be on a L or HD, and the additional pipe is added to the front ( had I got a HD version, the pipe would have been in the kit ).
Don't know if this still holds true on a S/C 5.5L 3V motor or not, just know what I had found out before.
#9
Here's my 2 cents....an inexperienced muffler guy.....to find the correct spot to place either an H or X, is to run a small line of paint down the side of the exhaust pipes 9both pipes), drive the truck for 10-15 minutes. Where the paint has blistered is where the "area of confusion" is......meaning that is where to install the H or X. Incorrectly placed when combined with thinwalled pipe (less than 16ga), the reverb(drone) is going to be increased and heard.
#11
My X and H sounded identical at idle and low RPM. At mid to high RPM is where the difference was. X is not as choppy sounding, and sounds a little smoother.
Now thinking back, I also had no crossover to start with. The H and X both made more rumble in general over no crossover at all, but to me they sound a lot better than no crossover.
Long story short, I think you will have the same problem with the H pipe.
Now thinking back, I also had no crossover to start with. The H and X both made more rumble in general over no crossover at all, but to me they sound a lot better than no crossover.
Long story short, I think you will have the same problem with the H pipe.
#12
Here's my 2 cents....an inexperienced muffler guy.....to find the correct spot to place either an H or X, is to run a small line of paint down the side of the exhaust pipes 9both pipes), drive the truck for 10-15 minutes. Where the paint has blistered is where the "area of confusion" is......meaning that is where to install the H or X. Incorrectly placed when combined with thinwalled pipe (less than 16ga), the reverb(drone) is going to be increased and heard.
#13
Thanks, guy! I know I am old, but regardless of all the CAD engineering, mfg, etc, etc (which is very good- don't get me wrong) sometimes the ol fashion way of doing things may not be "cool" or even "High tech", but it always seems to work when everything else fails.
#14
So today I took the truck back to the exhaust shop and had the stamped X-pipe cut out and had a H-pipe section fabricated in its place. They used a short 3" long section of 2.25" pipe flattened into an oval shape to create the crossover between the 2.5" pipes. The crossover is a bit further forward than the X was, and is as far forward as possible which is good.
Interior resonance is still worse than the crossover-less /divorced duals configuration but a bit less than the X-pipe. It is also in a slightly narrower RPM range now. Having a crossover is better than none so I figure i'm going to have to deal with what drone there is. Heck, I may even switch the setup for a pair of SISO Magnapacks down the road who knows
After H-Pipe sound clip:
http://www.youtube.com/watch?v=MojZUhEsKyI
Interior resonance is still worse than the crossover-less /divorced duals configuration but a bit less than the X-pipe. It is also in a slightly narrower RPM range now. Having a crossover is better than none so I figure i'm going to have to deal with what drone there is. Heck, I may even switch the setup for a pair of SISO Magnapacks down the road who knows
After H-Pipe sound clip:
http://www.youtube.com/watch?v=MojZUhEsKyI