89eliminator Posted May 28, 2007 Share Posted May 28, 2007 anyone running a dual exhaust setup on there 4.0. trying to figure a good way to go about it. kind of wanted them to be behind the tires not straight back Link to comment Share on other sites More sharing options...
Rokhound Posted May 28, 2007 Share Posted May 28, 2007 this is on a xj but may be you can build somthing like this http://www.naxja.org/forum/showthread.php?t=919788 Link to comment Share on other sites More sharing options...
jeepthing07 Posted May 29, 2007 Share Posted May 29, 2007 Dual exhaust on a 4.0 hurts performance from everything i have read. 4.0 needs alot of backpresure i guess you could run dual 1" pipes lol Link to comment Share on other sites More sharing options...
Pete M Posted May 29, 2007 Share Posted May 29, 2007 As long as the "dual" part is behind the muffler you should be fine. Eventually my new MJ will have "dual" exhaust. I bought a used system from an MJ being parted out. They exit right behind the tire and point sideways. It's propped up behind the garage and I can snap a pic if you'd like. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 29, 2007 Share Posted May 29, 2007 Dual exhaust on a 4.0 hurts performance from everything i have read. 4.0 needs alot of backpresure i guess you could run dual 1" pipes lol Not true, at least in my case. I've had a Hesco 4.5L stroker in my rig for a couple of years now. My original Mar 2005 peak dyno readings at rear wheel were 182.4HP @ 4250RPM and 228 ft/lbs torque at the same RPM. Last month I went back to Hesco for my over 2-year checkup. The peak readings this time were 208.0HP @ 3990RPM w. 276.8 ft/lbs torque. The only major performance changes I've done since 2005 were getting rid of the cat and replacing it with a 2.5" in/out glass pack, into a Walker (the Flowmaster was too loud for me) single 2.5" inlet / dual 2.5" outlet Hi-Flow muffler, then dual 2.5" pipes all the way back over the axle exiting under the bumper. Also Hesco had to lower the fuel pressure from 44PSI to 38.5PSI to get the best dyno readings. Lee Hurley did the dyno runs himself, and was happy. I've read that you need lots of back pressure for the 4.0L engines too, but did not believe it. You just never know how mods will affect the engine until you put it on the dyno. Link to comment Share on other sites More sharing options...
89eliminator Posted May 29, 2007 Author Share Posted May 29, 2007 As long as the "dual" part is behind the muffler you should be fine. Eventually my new MJ will have "dual" exhaust. I bought a used system from an MJ being parted out. They exit right behind the tire and point sideways. It's propped up behind the garage and I can snap a pic if you'd like. yeah the plan was to make the dual part after the muffler to keep the cost down. if you get around to it, could take a few pics. thanks. Link to comment Share on other sites More sharing options...
Pete M Posted May 29, 2007 Share Posted May 29, 2007 Too dark now. I'll snap a couple tomorrow. If you're lucky maybe I'll even be able to find the energy to haul it out and prop it up in place under the MJ. :D Gotta do that eventually, right? Link to comment Share on other sites More sharing options...
89eliminator Posted May 29, 2007 Author Share Posted May 29, 2007 i will hope for the best pete. try to conserve your energy for the big task! :D Link to comment Share on other sites More sharing options...
offroader461 Posted May 29, 2007 Share Posted May 29, 2007 i had a single in dual out setup on my MJ and i liked it at first but then after a while just took it off and redesigned how my new exhaust ran....it a single flowmaster 40-series that dumps out behind the rear wheel(stock location) but above the leaf spring and tucked up out of the way Link to comment Share on other sites More sharing options...
Pete M Posted June 2, 2007 Share Posted June 2, 2007 Slight change in plans. I had to move the truck asap (city discovered it wasn't yet tagged :roll: ) and now it's not near the exhaust. But for what it's worth, here's a shot of the exhaust itself Link to comment Share on other sites More sharing options...
89eliminator Posted June 3, 2007 Author Share Posted June 3, 2007 thats what i was looking for. hows it made? Link to comment Share on other sites More sharing options...
mjtjnj Posted June 3, 2007 Share Posted June 3, 2007 Dual exhaust on a 4.0 hurts performance from everything i have read. 4.0 needs alot of backpresure i guess you could run dual 1" pipes lol Not true, at least in my case. I've had a Hesco 4.5L stroker in my rig for a couple of years now. My original Mar 2005 peak dyno readings at rear wheel were 182.4HP @ 4250RPM and 228 ft/lbs torque at the same RPM. Last month I went back to Hesco for my over 2-year checkup. The peak readings this time were 208.0HP @ 3990RPM w. 276.8 ft/lbs torque. The only major performance changes I've done since 2005 were getting rid of the cat and replacing it with a 2.5" in/out glass pack, into a Walker (the Flowmaster was too loud for me) single 2.5" inlet / dual 2.5" outlet Hi-Flow muffler, then dual 2.5" pipes all the way back over the axle exiting under the bumper. Also Hesco had to lower the fuel pressure from 44PSI to 38.5PSI to get the best dyno readings. Lee Hurley did the dyno runs himself, and was happy. I've read that you need lots of back pressure for the 4.0L engines too, but did not believe it. You just never know how mods will affect the engine until you put it on the dyno. Don, that's the setup I want (except for canning the cat) :roll: Did you have the 2.5" cat back, over-axle pipes custom bent? Did you have to remove your spare? Thanks! Tom (your chrome supplier) :USAflag: Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2007 Share Posted June 3, 2007 Don, that's the setup I want (except for canning the cat) Did you have the 2.5" cat back, over-axle pipes custom bent? Did you have to remove your spare? Yes, had them custom bent over the axle (have a friend w. a muffler shop) and kept the spare. welded on universal hangers on the cross member behing the spare, and used 3" S/S tips under the bumper. Here's some bad pics, will take some better ones when I get it up on the lift. Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2007 Share Posted June 3, 2007 Thanks! Tom (your chrome supplier) Hey! Just noticed it was you Tom! WTFO? That's a new rear bumper Tom, backed yours into a tree. Still have the front on though. How you doin'? Link to comment Share on other sites More sharing options...
mjtjnj Posted June 4, 2007 Share Posted June 4, 2007 Don, I'm good, but when I look at pics of your truck, I get disgusted with mine! LOL. Looks great, even the leafs are clean and painted, and the rear diff cover is great! Love the 'Bama cat! How are you? Your MJ must roar! Tom Link to comment Share on other sites More sharing options...
Pete M Posted June 4, 2007 Share Posted June 4, 2007 thats what i was looking for. hows it made? I don't know any details beyond what I can see, but the muffler isn't marked with a brand name so I don't know if it's a kit or custom. I'm thinking it's a kit since the pipe seems to be rust-resistant. The pipe is made in sections and welded together (poorly). I hope it sounds good, but the truck previously had an old super-cheap muffler barely hanging on so it's got to be better than before. :D Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 4, 2007 Share Posted June 4, 2007 Don, I'm good, but when I look at pics of your truck, I get disgusted with mine! LOL. Looks great, even the leafs are clean and painted, and the rear diff cover is great! Love the 'Bama cat! How are you? Your MJ must roar! Yeah, IB lucky to be away from the northern winters that tear up our rides. Those are new "Metric Ton" springs and haven't had a chance to get dirty yet. :D Have had the diff cover for years, and stuck it on awhile back when I converted the anemic rear drum brakes to Ford Explorer disks. I like the diff cover mainly for it's increased fluid capacity. The MJ's running about as well as I can get it, and the exhaust helps a lot. And I'm doing fine too Tom-san. Link to comment Share on other sites More sharing options...
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