Hey guys, I just installed a new exhaust in the car. It's hedman long-tubes (with s extensions to clear transmission crossmember), with a dynomax stainless x-pipe, performance cats, and perf. tube mufflers. It then exits out the back stock-ish.

Here's the thing, The x-pipe is LOUD. Not the exhaust note, that's actually fairly quiet (for a built 400...). In fact, driving the car, I can barely HEAR the exhaust note, because the x-pipe is making so much darn noise.

It's this "breathy" sound. I can't find any information on this, because all my searches (google and on here), just talk about how an x-pipe "makes the exhaust sound." That's not what I'm talking about, the exhaust NOTE isn't "raspy" (it's awesome actually), it's the pipes themselves, right under my seat.

It's really annoying. Has anyone else dealt with this?

Thanks.

 

Exhaust leak or a drone? Never heard anyone describe an exhaust sound like this?? The x is just a piece of pipe, nothing should be goin on unless its rattling against something or leaking

 

Get a sound clip

 

I don't understand.

 

I'm out of town this weekend, but I'll get a sound clip next week.

 

Ok, I took a video, you can't really SEE anything (it's dark under the car), so I just grabbed the audio track off of it.

You can tell how there are two sounds, one from the pipes under the car, and another from the actual exhaust outlets.

The first sound is under the car, then I walk to the back.

The first sound was NOT there with my old exhaust (same headers, same cats, same style of muffler, just no x-pipe, and it came out the sides).

Thanks!

 

Sounds like a typical chambered muffler too me.

What did your old exhaust system consist of?

 

Sounds normal

 

I'm not sure what you mean by "sounds like a chambered muffler?" The "under-car sound" sounds like that, or the actual exhaust tone sounds like that?


The old exhaust was long tube headers, into cats, then perforated tube glasspacks (8 inch case).

The new exhaust is almost identical: Same headers, same cats, and slightly longer perf. tube glasspacks. The only "real" difference is the x-pipe after the headers, and the fact that it comes out the back now, instead of side-exit.

Just to be clear, I'm not talking about the second sound (how the exhaust sounds out the tips), that's awesome. My complaint is that I can hardly HEAR it while driving, because the first sound (coming from UNDER the car), is too loud.

 

The first sound. It sounds like chambered mufflers.


What brand / model mufflers are you running?

 

Yeah, I guess it does sound a bit like that.

I'm using these: http://www.summitracing.com/parts/wlk-24215

 

Sounds like you got a solid roller cam too.

 

Nope, hydraulic tappet. Comp 260 XFI actually.

Why do you say it sounds like a solid roller? I've listened to the clip, and ALL the sounds you are hearing, are coming from the exhaust. That clicking sound is the pipes as well. That's part of what I'm talking about.

 

Does it have any leaks?

 

probably very small ones yeah. I mean, all the parts are slip-fit, and welded in, but not welded all the way around each one.

It doesn't really sound like a leak to me though...

 

Get your welder out and do it right. You would be surprised the weird noises exhausts can make when they leak.

Post pictures

 

Yeah, I'm going to take it down at some point anyways, because I initially shoe-horned the mufflers underneath the car, and they don't really fit. Now that it's all done, I know I can easily put them in the back, before the tips, and save myself a TON of ground clearance, AND make it way easier to mount/hang/weld.

 

Agree.


Take a pice of paper and hold it near the joints while the car is running.

You can find a lot of leaks that way.

FWIW, I don't think your exhuast sounds abnormal. Of course its hard to tell via recording on a computer.

 

At this point he can probably look for the black smudge on the pipes.

 

Thats what a free flowing exhaust with a cam sounds like. If you want it quiet under the car again, put manifolds and cats back on.

 

I think you may have missed part of my post dude.

First off, it HAS cats. Second, the only difference between this exhaust setup and the old one, is the addition of the x-pipe. Nothing else changed really.

 

X pipes can do this, I'd do like previously stated and make sure everything is welded completely around and see if it gets any better.


We used to call it Exhaust echo.. transitions in pipe size, sharp bends and anything else in the stream can cause sound waves to bounce back and do other strange things. X pipes can do some weird stuff, H pipes aren't as bad.




Mine does it too, I just ignore it.

 

Nope, didn't miss a thing.
When you added the X pipe to your system, 1 cyl fires and makes it to the X pipe, then from that point back, that 1 cyl pulse uses 2 pipes for "extra" flow to make it out. then when you have pulses hitting each other in there its a tad louder.
If your current exhaust is to small, the X will act like you added bigger pipe.
Perhaps a pic or a diagram of what you have going on would help?

Just a FYI: I'm a old fat guy, not cool enuff to be a "dude".