Exhaust routing and muffler outside of frame rail

[reynard101]

Thinking of moving my muffler outside the frame rails. I currently have some minor interference with the muffler and the driveshaft when the suspension cycles. Also thinking about adding a parking brake to the transfer case, this would help open up some room.

Any downsides to running the muffler outside the frame rails? I know it could get mushed in while offroading, but I don't think it will that much of an issue.

Also how do you have your exhaust routed if running muffler outside frame rails?

 

[Apogee]

I've seen a few different installation done this way, some with fenderwell exit headers and others that could squeeze between the top of the frame and body due to a body lift. It's a solid option IMO for those not running two tanks, and takes advantage of a bunch of otherwise mostly unused space. It also allows you to run a larger muffler should that be something you want. Most of the installs I've seen dump out in front of the rear tire, so if your goal is to get all the way to the back, you'd have to figure out how to get over the rear end, past the shocks, etc.

 

[nvrstuk]

Apogee nailed why I did it...I needed to quiet the stroker down so we could hear inside the 1/2 w/o yelling. 22" bodied mufflers fit great. 4 link really makes it a tight squeeze for running dual pipes with big bodied mufflers, with 7" extended WB and a 22.8 gal fuel tank that rides high and tight but is not cut i to the bed...everythings custom but it works great. Floors are also lowered on the DS 2" and raised on the PS 2" so the mufflers are several inches above the bottom of the frame rails for clearance.
It had to exit out the back for noise reduction since my rig is not only a trail rig but a DD that easily runs up 1500miles/mo.

If you're interested to see how it all fit you can check my build thread here:
http://classicbroncos.com/forums/showthread.php?t=278607

 

[68ford]

The space between the frame rails around the trans and t case make it all worth it. Can easily run fuel and brake lines and battery cables on the inside of the frame and worry about heat. Mine exit in front of the rear tires. Getting exhaust out the back could be an issue. But unless you are low to the ground and have more than average up travel from ride height it can be done.

 

[Broncobowsher]

I have done a single Flowmaster 70-series under the passenger seat. the passenger exhaust was easy. the K-code manifold exited such that I could go over the frame and drop outside the rail. Driver's side crossed over and went under the frame just behind the radius arm bracket. The muffler tucked up to the bottom of the rocker.

The downside to the outside the frame rail exhaust is you are pretty much forced to do a dump in front of the rear tires. Not much option for routing.

Do you have a body lift? That would open some more options between the frame and body.

 

[68rockcrawler]

I have an Atlas clocked up to where it is almost touching the frame so I'm about to run my exhaust outside of the frame. I just bought some tight exhaust bends to come off the bottom of my WH Shorty headers and up over the frame rail. I'm not too excited about starting that project as there it will be a tight squeeze even with a 2" BL.

I also want a crossover connecting the 2 pipes together, which will be interesting to squeeze in there up and over the frame again and over the rear driveshaft.

 

[reynard101]

I've got a 2" body lift. Will definitely help going between body and frame to outside of frame rails. My current exhaust has a bunch of twists and turns to miss the transfer case and the axle wrap bar. I'd like to exit behind wheels, but that may mean routing the exhaust back in between the frame rails to exit back there. I currently have a Dynomax VT, it's ok, just a little louder than I want. Have a Walker "big muffler"on order.

 

[nvrstuk]

Looking for better pics...my Bronco is not by my side right now.

 

[68ford]

https://www.instagram.com/p/BI0QbxsD7yA/?utm_source=ig_share_sheet&igshid=1s0w6ok4z5o83
I took advantage of no side tank. Mufflers are able to be higher than the frame slightly lower than the body. They are far enough away I do not feel heat in the floor.

 

[reynard101]

https://www.instagram.com/p/BI0QbxsD7yA/?utm_source=ig_share_sheet&igshid=1s0w6ok4z5o83
I took advantage of no side tank. Mufflers are able to be higher than the frame slightly lower than the body. They are far enough away I do not feel heat in the floor.

That's where I'm planning on putting the muffler. I don't have long tube headers though so I have to snake the exhaust out.

 

[sanndmann3]

I started with some WH shorties and chopped them near the collector to turn the exit out over the frame and out. I have mufflers basically under the seat. I don't feel the heat there but my feet are toasty warm...