I have toyed with the idea of having dual exhaust pipes exiting the roof in the rear cap (Eagle Model 10). Yes, I am a former truck driver. I don't want it to look garish or odd, but to do it tastefully with minimal protrusion. Beyond the practicalities of running pipe up through the back with adequate heat protection, I am concerned about what would happen to the exhaust as I am going down the road. Would it swirl in the partial vacuum of the rear and be sucked into the intake, would it also coat the back of the bus with soot? You see exhaust pipes on the rear of transit buses, but they usually stick up a bit and have a flared end. It might be practical, but I do not think it is pretty. I was thinking of straight or angled pipes that do not stick up very far. Has anybody else tried this with good results?
I have a transit with built in left side up through the roof exhaust. It does soot up the back of the bus. But really like being able to see the exhaust easily through my driver's rear view mirror (I too am an ex Truck driver). The exhaust is contained in a separate, vented cabinet through the roof that drains back into the engine compartment. Good Luck, TomC
It would have to be contained in some sort of enclosure and insulated from the surrounding structure. There was picture awhile ago of someone that bought a bus conversions and the private owner did his own. When they were renovating it they removed the walls near the exhaust to find that the area around the exhaust was all chared and burned. Luckly it did not catch fire. The picture might have been on this site but not sure.
That picture was here. I remember it. Do they make triple wall insulated exhaust for an application like this?
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Well, Tom, Steve, and Scott have confirmed my suspicions that there might be some problems along the way. Being able to see the exhaust is worthwhile alright, but it might be cheaper to have a camera aimed at the exhaust. I would have to go through existing closets to do this, which are made of flammable materials, so it would require extensive shielding. I recall a story from one of Dave Galeys writings about how one of his Eagles caught on fire in the rear from an exhaust leak. Looks like stock exhaust will be it.
This mc6 I worked on with its 12v71 had awesome exhaust that had a great semi truck feel and look that I loved. Plus the sound coming out might have something to do with it seeming cool.
Check out this video on YouTube:
http://youtu.be/cqWH_NUY4xw (http://youtu.be/cqWH_NUY4xw)
Since the MC6 originally came with the 12V-71, turboing them wasn't that hard. The engine compartment is huge. Using the up exhaust through the space between the rear window and engine doors won't create any heat problems. The exhaust note is nice since they are using resonators to take the bark out of the exhaust note.
Just to show how large the engine compartment on the MC6 is, I saw one with a Series 60 in it and was struck with how small that large engine looked. Good Luck, TomC
It could be done probably easier if the conversions was just starting out gutted but trying to do this after the conversion is completed in my opinion would be a real headache. The next best thing would be to possibly check out a transit bus and see how it is done and then go from there. Maybe run the exhaust through a few pieces of the insulated stainless steel 6" chimney pipe sold in stove shops. Metalbestos was a supplier of this type of pipe. www.selkirkcorp.com (http://www.selkirkcorp.com)
The trick to an up exhaust is to NOT enclose it completely.
There is always a screened space of some sort alongside the pipe to allow the heat out.
Only have to insulate/shield 2 or 3 sides of the cavity in which the pipe is run.
Most of the new stuff is up exhaust, melting asphalt with emissions related temps is a concern.
Stay out from under the trees!
happy coaching!
buswarrior
Some of the later model Wanderlodges had exhaust through the roof. Most everybody ended up making modifications to them because of the heat and rust problems.
TOM
How about using the triple wall SS pipe they make for woodstoves? I believe they make it in smaller sizes.
Quote from: chessie4905 on April 06, 2016, 04:24:45 AM
How about using the triple wall SS pipe they make for woodstoves? I believe they make it in smaller sizes.
In the case of the Eagle, at least, the exhaust would be going through the curved rear cap. The triple wall pipe might be very good insulation wise, but the smallest inner diameter might be 6", and the outer might be 8" or 9". The sections will be straight, and they would have to be anchored to the cap somehow and hold the exhaust pipe as well. It can be done with enough space and time to figure it out, but it is looking to be difficult. There might be other insulated pipes for other purposes out there, but I think I would have to have a continuous exhaust pipe going through the interior section of the coach to be safe.
Instead of through the roof, why not run it up the side of the bus, just like trucks have? Good Luck, TomC
One time I was on a PACE shuttle bus in Chicago and I sat in the very back on the side where the exhaust pipe is. Even with the AC going, it was hot to the touch back there. If people are converting ground level exhaust to vertical just for kicks, perhaps it's better to leave it the way it was designed for. Although these days, new engines are so clean, you don't even smell or see the diesel exhaust so I question the expense of vertical exhaust on transits. I see quite a few newer semis with ground exhaust.
Bus exhaust pipes, if aimed directly at the ground, blow dust. That was annoying to me, so I turned it sideways toward the outside to minimize that problem. The Freightliner Cascadia Evolution I was driving last year had the exhaust to the ground under the cab, and it would blow dust all over in the drop yards. I can't remember now why they build them like that. I guess cheaper than up stacks, now that there is no smoke anymore.
JC
Walter- although your idea is one I agree with, it's unlikely I would ever undertake the fabrication myself. That being said- it has crossed my mind. With my GM and 8V71, the exhaust manifolds terminate on the driver's side, then drop to a corkscrew around the oil filter, pop into a muffler located in an inverted barrel that I can only see 15% of, then twist back out of the hole to end within 3 feet of the exhaust manifolds. The amount of heat retained under the bus is crazy to me, especially with all the fear of rear mounted 2 strokes running hot.
In my warped mind, a thick walled steel "chimney" open on the top and bottom with a standard vertical truck muffler would stay as cool as what I have stock. Wrap the 10" pipe with fire rated insulation then build around that with a fireproof enclosure and it would be as safe (or safer) than the drum muffler I couldn't get to if it did start a fire. I'm not sure what the reasoning was for containing it underside- another passenger seat?
My exhaust exits through the roof as is has from new. Was originally parked beside the air handler, but the factory HVAC has been removed. I replaced the original muffler with an inexpensive truck muffler last spring.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi64.tinypic.com%2Fa167w0.jpg&hash=73886a1e95f5738be8397408a8b887fdbcf21db3)
As usual, TinyPic rotated my photo 90 degrees left.
Completely happy with the truck muffler, and it cost a fraction of the one sold by Gillig.
Jim in NC
This thread has generated more interest than I expected. It looks like there are a lot of us that would like to do it, but have not completely figured how. Don's idea of a chimney is sound, there has to be a place for the heat to rise out of the area just like Jim's Gillig setup. The transits have devoted a lot of space and hardware to set their exhaust up, but as Crabby noted, some of the heat still radiates out. There was some company that advertised in Bus Conversions years ago that had a heat insulating pipe wrap, and another company that had a manifold ceramic paint that claimed heat reduction. There might be improvements in such technology for keeping heat inside the pipe. As Tom mentioned, some have added an external pipe on the outside of the bus, but that would require some heat shielding for pedestrian protection, and since most of the buses are somewhat curved, I have the opinion that it would hurt the aesthetics of the bus. JC brought up a point that is very important and is one of the reasons I considered roof exhaust in the first place - the kicking up of dust and dirt when you go into a non-paved area. (Our radiator fans and some A/C units can as well). Passenger buses stayed on pavement most of the time, but we go everywhere. On my 8V71 05 Eagle, which had a Series III Land Rover behind it most of the time (back in the nineties) I had the dual exhaust pipes extended horizontally to each side of the coach just below the bumper with chromed curved tips. I could see the exhaust in my mirrors, they were aimed straight back so there was no dust kick-up, and the exhaust missed blasting the Land Rover. I went that route because I had two four inch pipes to work with right there, and the radiator expansion tank above the engine blocked any clean path to the roof. The newer engines have less smoke in the exhaust, but my mechanical 6V92 has plenty of smoke that chokes people if their car is behind me when I take off, so I would still like to exit the roof, but it is going to require some deep thought to pull it off safely and look good.
I can't say for sure we will have the time to do this, but I want to have a stack fabricated for our 102C3 this summer. Our situation is unique in that our 102 has a flat back conversion done during the roof raise. So this might help a little. The issue for us is clearing the side mounted radiator....not sure exactly how I'll do that but I'm tossing around ideas. (https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fuploads.tapatalk-cdn.com%2F20160407%2F7fd3a3c36aa53fa51fd3a9c1702737e6.jpg&hash=205dad00b61e7db45705a1ea6114512f098fd19e)(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fuploads.tapatalk-cdn.com%2F20160407%2F8cd62e634a115d80b41fb4c46eef9fc9.jpg&hash=46a19da04d380f7c8bbf30578872a3e8c0dffd6f)
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Quote from: Scott Bennett on April 06, 2016, 07:00:21 PM
I can't say for sure we will have the time to do this, but I want to have a stack fabricated for our 102C3 this summer. Our situation is unique in that our 102 has a flat back conversion done during the roof raise. So this might help a little. The issue for us is clearing the side mounted radiator....not sure exactly how I'll do that but I'm tossing around ideas. (https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fuploads.tapatalk-cdn.com%2F20160407%2F7fd3a3c36aa53fa51fd3a9c1702737e6.jpg&hash=205dad00b61e7db45705a1ea6114512f098fd19e)(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fuploads.tapatalk-cdn.com%2F20160407%2F8cd62e634a115d80b41fb4c46eef9fc9.jpg&hash=46a19da04d380f7c8bbf30578872a3e8c0dffd6f)
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Scott, looks like you have the potential of at least one vertical stack once you clear the radiator. I found a potential source of heat shield wraps at heatshieldproducts.com (http://heatshieldproducts.com). One insulated pipe inside of another insulated pipe might do it.
GMC Fishbowl transits had a three-piece rear window. One center large section, flanked by two smaller pieces on each side. This arrangement made it easy for them to offer what was called their "Clean Air Package."
As you can see in the photo below, the RH rear small glass was replaced with the engine air intake. The LH small glass's removal allowed for the vertical exhaust. There were modifications inside the coach to accommodate these exterior changes that consisted of 90o curved metal panels that went from the side of the coach to the engine cradle/rear window vertical support posts. These curved double panels were well insulated and sealed to prevent any type of leakage.
FWIW & HTH. . .
My similar exhaust through the roof on my AMGeneral.
Quote from: TomC on April 07, 2016, 12:29:23 AM
My similar exhaust through the roof on my AMGeneral.
Tom, you had said before that you got some soot buildup on the rear. It looks like your pipe is pretty well up over the roof, it must mean that the rear vacuum draws the exhaust down to swirl the back. I wonder whether it makes much difference where the exhaust exits as far as the soot problems go. You definitely will not stir up dust. Does the soot buildup occur evenly across the back, and is it a slow buildup over weeks or sooner?
Soot builds up in a matter of a few days. But-it does wipe off with a dry cloth very quickly (about once a week). I do get black smoke (even with a fuel modulator running off my turbo boost) on take off. It is pretty even in the back. I imagine there's some oil mixed in also. Good Luck, TomC