Requesting help with design of exhaust/nerfs - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 03-11-2001, 12:49 PM
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Requesting help with design of exhaust/nerfs

77CJ5, 304v-8, fenderwell headers, crappy mufflers.

I just did a 4" lift (replacing the previous owner's add-a leaf suspension) and was trying to figure out why it didn't have more clearance...I realized it's because of the steps/exhaust on the jeep. The headers stick down nearly 6" below the bottom of the tub, right in harm's way. The jeep has aluminum psuedo-running boards that also stick down about 5" on the side...and right now, the mufflers are attached directly to the headers, and have a 90 degree elbow on the end of them for a turnout. I've decided that it's time to redesign the under-jeep area... Here are my design criteria:
1. Maximize under-jeep clearance.
2. Run exhaust to back of jeep, exiting right behind rear tires.
3. Create new rocker panel protectors to save fiberglass body.
4. Keep fenderwell headers (They're on there, they work well, they don't leak, they sound good...did I mention that they're on there and don't leak?)
5. Use a muffler that doesn't sound like a tin can.

So what I'm tring to do is concoct a way of using a much smaller (dimensionally) muffler, and running an exhaust line outside the frame to the rear of the jeep...and then creating new rocker panel protectors that are higher clearance. I've got some ideas about the rocker panel protectors...but the exhaust is driving me batty. I've even considered running an exhaust line from the headers up over the frame and back inside the frame, but that would be pretty lame. What I really need is a muffler built out of some really heavy duty pipe that could be integrated into the rocker protectors [img]/wwwthreads_images/icons/wink.gif[/img]. But that's just a PIPE-DREAM (get it...ha!).

Anyone? Anyone?

Moneyless, Will weld for jeep accessories.
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post #2 of (permalink) Old 03-11-2001, 02:35 PM
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Re: Requesting help with design of exhaust/nerfs

I looked into that, 4" sch 40 case w/ a preforated tube down the middle and fiberglass insul. packing. (like a dirtbike uses.) You would have to do some serious "frenching" at the collector end, and keep it repackable.

post #3 of (permalink) Old 03-11-2001, 05:12 PM
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Re: Requesting help with design of exhaust/nerfs

Farmjeep,
My mufflers are an oval shape and set under the door area right up against the underside of the jeep, they exit in front of the tire and are somewhat loud, but you could easily extend the pipes out the back. I just don't know if there is enough room in the area of the rear springs shocks tire etc.
Miles

"When in doubt go faster"
'64 CJ5, 351W, T-18
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post #4 of (permalink) Old 03-11-2001, 10:49 PM
 
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Re: Requesting help with design of exhaust/nerfs

Wouldn't they start to melt shoes if they got hot? Just something to think about.
BarrelRoll

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post #5 of (permalink) Old 03-12-2001, 11:29 AM
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Re: Requesting help with design of exhaust/nerfs

Dirtrod, tell me more about these motorcycle mufflers...

Moneyless, Will weld for jeep accessories.
post #6 of (permalink) Old 03-12-2001, 12:11 PM
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Re: Requesting help with design of exhaust/nerfs

Farmjeep... They use a outer tube thats part of the exhaust sys., inside of that is a smaller tube that is preforated with lots of holes it and has flanges on the ends so that it just fits into the outer tube, (you made need some mid point flanges if the muffler is very long). The inner tube is wrapped with fiberglass and slid into the outer, held with a snapring or bolt. Leave some clearance so things don't stick together, cause you will want to be able to repack it once in awhile.

... I was going to baloney cut mine ahead of the wheel, but if you made a removable endcap/reducer, you could add tailpipes from there on back.

post #7 of (permalink) Old 03-13-2001, 10:16 AM
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Re: Requesting help with design of exhaust/nerfs

So the exhaust just passes through the inner tube all the way back? Is this just normal fiberglass insulation, or something special?

Moneyless, Will weld for jeep accessories.
post #8 of (permalink) Old 03-13-2001, 03:53 PM
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Re: Requesting help with design of exhaust/nerfs

Hi,
Why not just stick a cherry bomb (glasspack) inside a bigger pipe? A 2" diameter bomb should fit inside a 4" diameter pipe. The outer pipe could have some small holes drilled in it for ventilation so it could act as a heat shield. Cherry bombs are very free flowing and sound fantastic. Make sure to put a wire screen in there somewhere for spark arresting, otherwise backfireing could start a major forest fire. You can get them in all sorts of differant sizes from Jeg's (www.jegs.com) or your local auto parts store. They either have pipe ends or flange ends to bolt right up to the headers.
Regards,
Josiah

Hillsboro, OR
1955 Willys CJ5 Buick 225 V6 160HP 270ft-lbs, T90 trans, Warn OD, PTO winch, Spicer 18 T Case, RS9000's, Dana 25F/ 44R,
5.38:1 gears, 11" brakes, Bestop Supertop, Hurculiner
post #9 of (permalink) Old 03-13-2001, 04:10 PM
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Re: Requesting help with design of exhaust/nerfs

I'd use standard house insul. it won't burn, you could try rockwool also. You can use cherrybombs, but they don't have much insulation. I ran them for years, but they're just too loud for my tender ears now. I think flowmasters are the best sound for the money. I'm running flowmasters with a s.stl cage around them, holding up well so far.

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