Header Noise Reduction
 

The headers on my FE are VERY LOUD (I know - duh!). Is there any way to dampen them with header tape / something else? Thanks for any help!!

The problem is the sidepipes most likely, not the headers.
A good muffler shop should be able to replace the baffled section of the sidepipes for a reasonable cost.

Thanks - forgot to note that the car is a '68 Shelby Convert. Mufflers are the quieter version of FlowMasters, and it's VERY LOUD, but not much louder than BB Cobras.

Do you have a crossover pipe in the exhaust?
They do help quiet down a car's exhaust, especially at idle

No Crossover pipe. Just received car a few days ago. Is it possible to add this? Is it smart to have this anyway? I have 2 1/2 inch exhaust. Thanks!

Yes, the local muffler shop should be able to add it. Get it with two pairs of header collecor-type flanges so it can be removed so you can remove the tranny if needed. They also improve power. win-win, except paying for it.

Thanks. Just spoke to another fellow who said the same thing. In the next couple of weeks I will take your advice and let you know the results. Thanks VERY MUCH for your time.
Ken

Also, make sure your exhaust pipes dump out well beyond the muffler outlet - all the way to the rear bumper. I had a set of Corvair turbo muffs on a Mustang years ago, and when the muffler outlet dumped the exhaust with only a 6 inch long turn down pipe, it made almost twice as much resonation.

Thanks, Mr. Zoom - they do exit at the rear a la stock GT 500 pipes. Thanks for your suggestion! Let me know if you have any other ideas....
Ken

Crossover (H-Pipe) / Magnaflow Mufflers
 

I just bought a West Coast Cobra with a 460 c.i. 385 engine, and I'm waiting (impatiently) for it to be delivered. It has Vern Redel's standard 4 into 1 headers with a short collector, then a flange the muffler bolts to. It's like the one in those photo of a different car (West Coast Cobra Dream Machine built by customer Mark picture 07). I like the sound, but was thinking about making some modifications to tone it down a bit, make it a bit mellower, and perhaps make it a bit more acceptable to those with 'sensitive hearing'.

1. Regardless of whether I change the mufflers, adding a crossover pipe (a.k.a. H-Pipe) seems to make sense. From what I understand, it will result in lower decibels, a mellower and/or deeper tone at lower RPMs and make virtually no difference at higher revs. The challenge of course, is how to hook it up and route it. My thinking is to tap into the pipe after the collector and before the muffler in an area under the heat shield, making it less visible. It would probably need to be routed under the higher section of the oil pan or under the transmission but, either way, the centre section needs to be removable. Obviously smaller diameter tubing will make all of this easier, while larger may be more effective, but I can find no information on whether others have used the same size or smaller tubing on the H-Pipe as their exhaust pipe / side pipe. Any thoughts as to minimum size of the crossover pipe? Should I have some flex tubing in their somewhere, or is it okay to make it all out of rigid tubing?
   
2. I'm also looking at swapping out the existing mufflers and going to Magnaflow 4" O.D. SS mufflers with a 2.5" core. I have a Magnaflow system on my Infiniti FX35 and like the sound as it's mellow - less harsh (at least to my ears) than FlowMasters and some other 'performance' mufflers. I also have reason to believe they flow pretty well. Magnaflow's 22" body (28" overall) is p/n 10436, and the 18" body (24" overall) is p/n 10426. There are heat shields on the existing pipes which may need to be re-curved slightly to fit the slightly larger O.D. but I'm pretty sure they'll work. Anyone have any experience with Magnaflow mufflers on side pipes?

Thoughts? Comments?

Crossover Pipe Sizing
 

Finally found some information on sizing of crossover pipes:

"Balance pipe sizing seems not to be overly critical. The only really influential dimension is the pipe diameter. This needs to have an area at least equal to that of a 2.25-inch diameter pipe (4 square inches) with 2.5 to 2.75 inches being preferable. Though limited to tests on engines up to a little fewer than 600 hp, there seems to be no measurable benefits to using a crossover pipe bigger than 2.75 inches in diameter. As for the crossover length, dyno results indicate that 18 inches responds in virtually the same manner as 72 inches long."

Read more: Auto Exhaust Science

Based upon that, looks like I'll go with 2.5", assuming my exhaust shop can figure out a way to make it work.

I've given up on the crossover / balance pipe idea. I was concerned about the noise levels when the car was inspected, but they completely blew past them.

I'm now in the process of replacing the current, very restrictive inserts (1.625" I.D.) with a set of Patriot 3.5" augers from Summit. FedEx says they'll be here Friday, but they've lied to me before.

Cycleguy, let me know how this change works out as this is a winter project I have set up for my WCC.

Turns out I couldn't get the old inserts out of the side pipes without cutting them close to the rear end plate of the inserts. Once I did, I had to separate the insert core from its end plate. I couldn't get the end plates out, so I cut numerous radial slots from the core to the side pipe shells and hammered each pie-shaped section flat, or as flat as I could get them - creating an opening at least 2.5" in diameter. With the exception of the end plates, the old inserts came out okay, though I had to take a large rod to push out the fiberglass packing.

The Patriot augers were a bit snug, and as I've seen elsewhere, I bent the edges rather than grinding off extra material. I also used a smaller section of tubing through the auger cores to join the pair in each pipe end-to-end, held in place by 1/4" bolts through the cores. They're in now and sound good and, quite frankly, quieter on the road than I thought they'd be. When idling or at low revs they're certainly a bit louder and less mellow than the old inserts, though they tend to rattle a bit. I'm going to pull them again and straighten some of the bends I put in the spirals to snug them up in the side pipes. I'm also going to pull the tubing from the middle of the cores to allow a bit more flow, and it will be interesting to see what that does to the volume and tone.

The bottom line is I like them, but they still need a bit of tuning.

BTW, the slip connector on one of my side pipes had anti-seize in it, and it was MUCH easier to get apart than the one without. I applied anti-seize to both when I re-assembled them, and it helped with that as well.

Just for kicks I started the car when I had both side pipes off (have to do it, right?), and wow, was that ever freakin' loud. I guess I should have expected that with an open collector 4' from my ears!

Finally, I used band clamps (http://www.summitracing.com/dom/part...3279/overview/) to join the severed sections of the side pipes. They're under the heat shields, so somewhat hidden, but I'll need to assess my options longer term. I may go with some of these: http://www.summitracing.com/dom/sear...g&autoview=SKU