I'm trying to start a discussion on stacks because it's one of the routes that I'm seriously considering (though I don't want to mess with it until my powertrain warranty is out, so I have a while to think on it). Nearly all of the discussion that I can find online deals with diesels, and much of the interest there caters to a rather extreme end of that community focused upon loud noise and at time, billowing clouds of locomotive smoke in the bed. Those goals are essentially opposite mine: I like how quiet a stock truck is, and I have no desire to put out soot EVER. I had a jacked up 4x4 with a custom full dual exhaust with headers, high flow cats, thrush glass packs and turndowns in high school....I do not wish to return to those days. At the time time, I note that a stack is at least theoretically the most efficient way to get exhaust gas out of your engine while obeying the law and avoiding the risk of asphyxiating yourself or your loved ones. This thread is for exploring the possibility of a stack exhaust that isn't built to to frighten children and environmentalists.

The proposed benefits for a stack exhaust seem to be its natural draft and very short pipe, which seems to maximize flow if you are constrained by laws saying your exhaust must exit behind the cab (i.e. those of us who aren't required to have it exit behind the rear wheel). This seems to have several benefits over a turndown or exhaust in front of the rear wheel in that it avoids getting exhaust gas and water on one wheel, doesn't directly heat one tire, and mitigates the extra pipe length with natural updraft. The costs, which are well known and often exploited, are noise and at least some lost bed space. My truck is a hybrid, and thus a stack is either a blessing or a curse, as the battery and charge controller are both located above and flanking the muffler, as is a small electronic device that forces the entire exhaust stream to flow through it (not sure what this is, have never seen one before). There is a pathway with clearance for a 4" pipe to travel upward from the existing exhaust path to the bed, but it would be perhaps 18" from the side wall of the bed. This is an issue for me, but those without hybrids may have an easier time of routing.

With regard to the space consideration, my idea is the use of a tool box with a compartment which surrounds and isolates the in-bed portion of the exhaust run. From there, one could route it above and behind the rear passenger cabin with an outward facing Ozzie or West Coast tip.

For noise, my presumption is that the muffler would still heavily influence the sound, though this is the part that I'm having the most trouble researching as most of the folks with stacks have designed them to be LOUD.

Anyway, I'm thrilled to hear criticism and ideas, but I would appreciate people limiting posts to things that they actually know versus extrapolating stereotypes about stack exhausts to the entire realm of possibility. I don't want to discourage folks from thinking through this, but posting "every video of a stack exhaust on youtube is crazy loud, so they are bound to be loud by the laws of physics" doesn't really help. If you can figure out or guess at why what has been done DOES or DOES NOT define the realm of the possible, I'd love to hear it and maybe it will help someone else too.

 

I really wonder if the natural draft would have any meaningful effect. Also, will the exhaust really be that much shorter? By the time you run it up through the bed and to the roof, you are probably within a foot or 2 of the length of a stock exhaust.

 

I agree. I think if you really want to shorten the length of your exhaust the best option is a turndown post cats. Problem is this is crazy loud without a resonator/muffler and to add that you naturally lengthen your exhaust. Pretty hard to have your cake and eat it too.

On a side note, I'm all for fun and interesting exhaust setups. Personally, I struggle seeing stacks on anything other than a diesel. For gas trucks I much prefer to see a nice flush hood, bumper, or side exit.

 

Stacks are for highschoolers trying to keep their virginity. Rear exit is sexy... Side is for looking stock. There is my opinion...

 

Just put a dump under the bed right after the muffler. Just as short as stacks, doesn't look dumb (my opinion), and doesn't take up bed space.

 

I think you're overthinking the exhaust....

 

Thanks for the thoughtful replies. I don't really want to do a rear exit with the aim of keeping as much exhaust off of trailers as possible. I think the length comparisons are likely accurate, and also that the the natural draft idea would at best overcome some of the other issues.

The other solution that I had considered was a side exit in front of the wheel. My major concern there is ruining tires: losing 5k miles doesn't bother me, but having seen a few blowouts first hand, anything that I can do to avoid it is a priority. If folks have experience with side exit in front of the wheel, I'd be thrilled to hear that.

 

Is there a reason you are worried about exhaust on the trailers? I have towed my travel trailer behind my Ecoboost for >13000 miles now with no ill effect. My truck has overheated regularly and warped exhaust manifolds twice so I am guessing my exhaust temps are about as high as anyones.

I have no idea on the tire issue. I guess it could be an issue but not really sure.

 

I cut my exhaust off and essentially made it a "turn down" after the pipe went over the rear axle. I didn't like the look of the side exit exhaust and the Corsa Sport exhaust system I have doesn't offer a dual rear exit. Plus if I went dual rear exit I would honestly want to upgrade to the Limited style rear bumper and that was going to be too expensive. So I cut the exhaust off under the bed and now you don't see it at all. I'm really happy with how it turned out. I don't have any soot or anything under the truck except right on the tip of the exhaust tip itself (which occurred even when the exhaust was a side exit exhaust). I'll see if I can dig up a picture of my setup if you're interested.

 

I am interested in a photo of your exhaust.