Engine Exhaust Through The Roof

DoubleEagle · April 04, 2016, 08:23:56 PM

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?

TomC · April 04, 2016, 09:23:56 PM

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

scanzel · April 05, 2016, 03:29:21 AM

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.

Scott & Heather · April 05, 2016, 05:57:11 AM

That picture was here. I remember it. Do they make triple wall insulated exhaust for an application like this?

Sent from my iPhone using Tapatalk

DoubleEagle · April 05, 2016, 06:49:59 AM

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.

Scott Crosby · April 05, 2016, 07:42:22 AM

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

TomC · April 05, 2016, 08:34:59 AM

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

scanzel · April 05, 2016, 08:36:56 AM

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

buswarrior · April 05, 2016, 08:44:19 AM

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

oldmansax · April 05, 2016, 05:03:04 PM

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

chessie4905 · 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.

DoubleEagle · April 06, 2016, 06:40:49 AM

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.

TomC · April 06, 2016, 06:49:39 AM

Instead of through the roof, why not run it up the side of the bus, just like trucks have? Good Luck, TomC

CrabbyMilton · April 06, 2016, 06:56:52 AM

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.

lostagain · April 06, 2016, 07:16:35 AM

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