Sidepipes

So I have a 65’ CJ5 with a Dauntless swap. It’s been a challenge but got the engine running strong. My question is about exhaust routing. I considered getting Hedman fenderwell headers and having dual side pipes. However the fuel tank is in the stock location under the drivers seat. Would this cause vapor lock issues? And what’s everyone’s opinion on this setup in general? I do have the stock iron manifolds so I could also run those.

 

Fender well headers & side pipes are too loud for most trail running.

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Are you talking about actual sidepipes like on an old Corvette? Those are kinda old school cool, but on a CJ, nope.
If you're talking headers with the mufflers under the floorboard and the exhaust exiting in front of the rear tire, lots of Jeeps are set up that way.
Drawbacks are exhaust smell & noise due to the tailpipe coming out right underneath you, and the mufflers being vulnerable to damage off road.

 

I ran the side pipes you mentioned years ago, and yeah, too dang loud and I did notice a drop in torque.. I went to the old thrush Turbo Mufflers and was much happier with the sound ant seat of the pants feel a bit more torque when pulling..

 

If you can ignore an occasional whiff of exhaust and use decent mufflers, that system works pretty well and no heat issues with the fuel tank in my experience. My 67 still has that layout with Walker turbo mufflers and I never had any problems with it. My CJ 3B also sports that system using Hooker headers with the sbc. On the 225 that system produces more low end torque than the stock manifolds, actually more torque over the entire rpm band along with improved mileage. Overall, I rate that as better than the stock arrangement with that exhaust passing under the cross member with a big sign on it: "smash me". On the 3B, I have aluminum heat shields between the tub and mufflers as well as skid plates beneath them.

 

I'm running the side dump with turbo style mufflers (not side pipes)
Mine are angled back 45° a high lift jack handle will bend them back out of the tire when you catch a rock. But the exhaust isn't lingering next to me.

Heat has only been an issue once with my 4cyl and a weak pump, anything with a return line should be fine. It's not the heat of the tank but heat on the fuel line that causes issues.

I have manifolds and S bends down under and around the frame behind the front spring hangers before the clutch and brake pivot.
Currently 2" duals but I plan on switching over to a crossover and single muffler on the passenger side. That puts the driveshafts and crunchy stuff all in a 2' wide path so you don't have to swerve so much to crush everything.

 

I guess my terminology wasn’t very good . Yeah I’m talking about pipes and mufflers outside the frame rails with the end of the exhaust system in front of the rear tires.

 

My setup is very similar, cept' it's not 'lumininium.. I just went with 1-1/2 tubes under them as part of the nerf bar..

 

I run Hedman headers & thrush turbos, the heat is not terrible directly underneath the seats or gas tank. I have contemplated putting in heat shields on the slanted part of the floor where the collector tube of the header resides, that's where most of the heat comes through.

The exhaust fumes are actually not that bad. This is certainly not a clean burning modern car. The exhaust is much more noticeable in old cars regardless of where the pipes come out. If the pipes come straight out to the rear the exhaust has a tendency to wrap up and around behind the jeep and come into the passenger area when you stop.

 

Here's some pictures of mine
Front wrapping around the old steering box and stuff.


Then out in front of the rear tire but angled to get the best possible sizzle when the fuel dribbles out the filler.

 

I’m running fenderwell long tube headers. They used to exit in front of the rear tires, each side. But I like the rear exit better, IMHO.

 

I just did this over the winter, I used headman outside the frame headers and had them ceramic coated and installed the dynomax turbo mufflers and I bought 2 1/2” dumps becuse the 90 bend out me into the rear tire. They are way to loud, I think I’m going to try some walker quiet flow mufflers. Over all I did notice some more low end power for sure.

 

any time I hear "side pipes" I can't help but think of Bill Cosby talking about when he bought a cobra from Carol Shelby. him talking about the PIPES!!!!!! haha

 

2.5" is big for duals.
What I found for 150hp on under funded calculators was:
1 5/8 to 2" for duals.
2.25 to 2.5 for single.

I'm not saying too big hurts performance but it's not economical, harder to package, and loud.

 

That’s probably the most common setup for V6 Jeeps on this site. Mine is the same except I turned the exhaust dump IN not out and down under the Jeep. I rarely smell exhaust.

 

Important you have them turned out, otherwise you're going to smell the exhaust.

The turbo mufflers (actually any real muffler) will keep the noise down, but they still drone at times.

Insure you mount the mufflers well as there is is lot of movement and vibration there.

The floorboards can get warm, especially in the summer, but after forty years, I've never had any fuel issues.

 

I like to be Quiet in the Woods, quiet as I can so we can see the woods, and the wildlife.

 

I have had mine both ways and dumping under the Jeep definitely helps have less exhaust smell. As the vehicle moves forward the exhaust moves under and away. The side exhaust is much closer to your sniffer. Wrapping back Aerodynamics can effect exhaust but I think it’s well dispersed by the time the exhaust is behind the Jeep. Unlike full system tailpipes that dump everything just behind the tail where a venturi effect is strongest.

 

big pipes sound cooler though....

 

WHAT??? I couldn't hear that last part.

You need a bag pipe and a cooler?