Mufflers keep blowing out
 

My sidepipe mufflers only seem to last a few thousand miles. Does anyone have any recommendations for mufflers with a minimum inside diameter of 2.5"? A complicating factor might be that the motor is a 496 CID FE with 804 HP (on nitrous) and I think the mufflers are getting the fiber filling blown out.

Anything with no fiberglass?

That large of an engine need a considearbly larger core.

Racing mufflers or under the car exhaust if---
 

496fe You are going to have the same problem most of the bigger motor guys are having with side pipes. First off, 2.5" per side is not big enough and costing about 12-17% of power loss. 3" to 3.25" will get you in the ball park. You need to do a back pressure test to find out how much you have when at max HP rpm. You want about 1-2 psi. My Street ERA exhaust is killing about 45HP in my motor at 6,000 rpms. It is quiet enough to pass most sound guns on the track. An under the car exhaust is about the only way to install a large enough muffler and still keep the back pressure low. Have you looked into spintech or Mr. pipes? I have 2 sets of pipes, one for quiet, Ya-right, 98db at WOT and race pipes 110db and WOT and more power. You may have to look and build your own set for what you want. 1 side note, if you are hitting the bottle, this will raise the EGT's 2-300 degrees and alot cook you mufflers and melt the packing material inside. Rick L.

There are mufflers with stainless steel mesh packing

Do you know who makes a SS packing with 3" core?

RL is right. My guess is that the exhaust is still at least 1,100 degrees when it hits the muffler. I don't think the fiberglass packing can survive those temps. The SS might?

Just curious. Where do you use 804HP with nitrous? Maybe you should investigate to see what type of ear plugs the top fuel dragster guys use. :)

Contact Iron Man here. Or Classic Chambered Exhaust. He makes nice mufflers.

You could also contact Lobak. It's a spiral metal core, no packing. Custom made to order.

You are right - there is a fair bit of drama when you pull the trigger. As long as the tires are warm, they hook in second gear.

Update:
-Have Classic chambered now - lasted 3-4,000 miles
-Lobak has kind a flatulent tinny sound to me. Maybe used the wrong ones. A friend used them on a 500 HP SBC and they killed HP
- Will check Spintech and other suggestions.

On your Classic Chambered mufflers which way do the louvers face? If they are facing forward and scooping in that hot exhaust you may want to reverse the direction they face away. Also as Rick said it sounds like you need bigger pipes. But there are a lot of high HP motors doing it with 2.5". Supercharged Mustangs at the strip come to mind. Fast Intentions in the San Fernando Valley (Northridge) may be able to help you out. That is their specialty. Daniel or Tony 818-882-2788. These guys are good.

John

496FE, you say you have my mufflers on now & they lasted 3-4,000 miles??? What happened? Also, you ran the 2.5" core Cobrapacks? With that kind of HP, why didn't you go with the 3" core versions? 2.5" is WAAAAAY too small when you are on the bottle. NOBODY has ever reported my packing blowing-out in over 3 years of making Cobrapacks.

Also, steel packing does NOT do a good job of absorbing & killing sound. The fiberglass mat I use will not melt or "burn out" at 1100^ F. Fiberglass does not have a flashpoint that I am aware of - I've tried to burn it. It would take WAY more heat than 1100 to melt it.

I'm building my own! I currently run a 4" side pipe that unbolts (four bolts) at the collector and then I bolt on a little shorty turn out to run open headers. When I want to or can, sometimes you HAVE to run muffled.

So, I'm buying a 36" long 4 inch aluminized "stack" from a truck supply store, I'll cut, weld, modify the basic 36" "tube" as needed. Then I'm buying two 30" Spirals which BOLT from the outside through the "stack" (4" pipe) with button heads screws at each end. The center core of the spiral is an open pipe. Need extra quiet? Plug the outlet of the center pipe, but that WILL cost you horse power. I'm working on a way to temporarily close the small center pipe when I need to, open it up again when I don't. Because they BOLT IN to the stack you can turn them around to face the other way if you want to try that.

Finally, the end piece, the turn out. This will be adjustable, like a jet nozzle for direction. Down or to the side with a ring clamp of some kind. Sound meter reading coming from the left? Turn the turn out away from the meter! Still to loud? Pop in the center pipe plug.

...this is my working theory, it looks great on paper, now I'm hustling the parts to make it reality.

Tom's Motorsports, has shown very little horse power loss with this type of system and has been using it for racing for several years now. Before they went "all spiral on us" they had problems with extreme heat or significant horse power loss. Spiral IS the key!

Talking to the owner of the Spiral patent thing the other day, he made an interesting comment. Fords are harder to get quiet than Chevies, I thought that was interesting. I told him I had an FE, I could hear him cringe on the end of the phone. :)

Get a hold of me for my 304 stainless exhaust. The muffler has louvers, not glass. They will last the time of your car.

cobrakev@galaxycable.net

I tell ya, you professional side pipe builders are missing a BIG part of whats going on lately. DB sound requirements at various race tracks and events. Take SAAC-35 on Sunday, 103 DB limit. Saturday, no limit, can run open pipes. A Hill Climb here in Southern Oregon in June, DB 95. Auto Cross track, local, 97 DB suggested, loosely enforced. Drag strips around the country are starting to crack down. The FUTURE is fast approaching, DB is the future.

So let's say I spend many hundreds of dollars on side pipes, you guy's gaurentee I can meet the various DB levels, without loosing to much h.p.? What happens if I can't? Throw out the side pipes or quit racing? How about a way to ADJUST the parameters for really quiet events or heck, run open headers when you can!


Seems like the ONLY readily available options are "side pipes", kit form, done. Not good enough, gotta have some options.

If it's too loud, use ear plugs, or buy a Cadillac. :rolleyes:

Damn dude, do you really think,.... we don't know whats going on ? :LOL:

I have a choice, either louvers or a glass pack. With a high HP motor, you'll be blowing them out in a short time.

If you want the sound to be adjustable for race & street, make or buy the mufflers like "SuperTrap".

"Seems like the ONLY readily available options are "side pipes", kit form, done. Not good enough, gotta have some options".

If these aren't "Good Enough",..........make your own and stop crying about it !

There's always one in the bunch.

I can't make everyone happy, all of the time.

FUNFER2/Kevin,

Funny reply!!! It appears that the only way to get what you want is to build your own. Doesn't appear to be kit's that can not blow out on high HP motors and not lose HP.....

Intresting thread....

Scott-

...thats the game plan! :)

FUNFER2/Kevin - I know you are having a little piece of me, but when I first got them, they were quieter and more mellow - everybody I know (especially neighbors) now make cracks that they went from hmmm to blaaaat in 3-4,000miles.

For the life of me, I can't remember if I faced the louvres forwards or backwards.

Rare Iron... could they be filling up with soot, rather than disintegrating?

I keep Classic Chambered on the shelf I have had such good results with them. Available in any length, true 2.5 or 3" ID's, packed or unpacked and you can face the louvres forward or back. It's simple noise or horsepower, pick one as you can't have both.

It would seem with the spiral application you can come very close to having both. I've seen the Dyno charts from an independant (not associated with the Spiral guy). Minimum h.p. loss, it was quite surprising. DB was around 103, not quite good enough for me though. I expect to loose more h.p. in the quest to get below 97 DB, even 95 for some events.

496FE- it was not pointed at you. ;)

The glass packing will slowly burn up and blow out. That's why I like my stainless, that won't rust, and no glass to be spent in a few years. When you consider the cost of replacing your mild steel pipes, any type of coating (ceramic, powder ect.) and mufflers, against my (or any other builder) $2,100 stainless system, it's a no brainier to me which way is better and more cost affective, if you plan on keeping your cobra for several years. They are also much easier to keep clean and bright.

Plus,..... the looks of polished,...... stainless !

I even gained 6 HP,.... at idle.
26 HP around 5,000 rpm and 22 torque at 2,500 rpm.

My mufflers aren't really that loud, until I get on the go pedal. My wife thinks the same thing. You can have the louvers toward the front but, you will loose torque, how much,.... I haven't tested yet.

I doubt you have a debris problem, and the glass fibers either burn up or blow out the turn out. On the chassis dyno, I clogged up the o2 sensor with glass, so that was a $150 replacement. :LOL: