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Author Topic: Opinions on Routing Exhaust (Video Question)  (Read 1664 times)
Midwilshire
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« on: April 28, 2013, 02:31:07 PM »

I purchased a Powerhouse 3100 generator and fabricated a platform for it where the MCI-5C A/C compressor used to live.  Now I'm trying to figure out where to run the exhaust.  The current considerations are:

1.  Straight out the back under the tail lights.
2.  90 degrees down through the floor.
3.  90 degrees up into the radiator compartment (used only when bus is off)
4.  Some combination of these.

Any advice would be appreciated.  I'd also like to know if I risk overheating the generator by running it with the doors to its compartment closed.  I have about 1.5 square feet of holes in the floor of the compartment and a 10" fan blowing up into that space. 

Here's the video that explains the above question:  http://www.youtube.com/embed/IuX5UPqyBG0

Thanks,

Mike
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Michael & Gigi
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bevans6
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« Reply #1 on: April 28, 2013, 04:16:56 PM »

I'd just run the exhaust out by the shortest path possible, those engines hate extra exhaust back pressure.  They throw off an amazing amount of heat, they are not rated for enclosed use - but the engine compartment is the best place for it.  Open up the floor under the generator completely, and give it a path out at the top, and convection will help cool the engine.  You'll just have to do a test as to how hot it gets.  I have a similar Yamaha 3000 watt inverter generator, and I can't run it in the AC condenser compartment for more than 20 minutes.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #2 on: April 28, 2013, 04:26:39 PM »

I would not go up into the rad intake: you might want to run the gen while driving to power air conditioners.

I would not run it pointing at the ground: it would kick up a lot of dust, or ignite dry grass on fire.

I would run it out the back or the side. Preferably not through a body panel: the more holes in the side of the bus, the less it looks like a bus. You could go down and out under the bumper or the side, then attach an extension to go up along the side of the bus to the roof for camping.

And, like Brian says, experiment to see if it will run in there without overheating.

JC 
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JC
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« Reply #3 on: April 28, 2013, 05:12:58 PM »

90 down 90 out under the bumper would be my choice too JC not through the body that's tacky 

I would use the fan to pull the air out not in those units are not strong enough to expel much air
« Last Edit: April 28, 2013, 05:31:06 PM by luvrbus » Logged

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Iceni John
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« Reply #4 on: April 28, 2013, 05:49:00 PM »

Regardless where and how you run the exhaust, you'll probably need a short length of flexible pipe to connect the gen to the rest of its exhaust pipe.   After looking at all the options when I installed my gen, I used an end-of-spool remnant of 3/4" TracPipe CSST flexible (or is that flxible?) stainless-steel gas pipe.   The TracPipe fittings, though expensive, do not use O-rings in them, making them better able to handle exhaust temperatures than the other brands of CSST like the ProFlex I'm using for my propane system.   You can then use a female CSST fitting threaded onto a suitable length of galvanized pipe nipple for your exhaust pipe, and even run it inside an outer stainless tube if appearance and heat-protection are important for you.

Don't forget to provide easy access to check or change the gen's oil.   Maybe a heavy-duty slide mount and a telescoping exhaust will help for that?   Also, if you can hook up a temperature switch that will shut down the gen if it gets too hot, that could save an expensive (or worse) problem if it overheats or if the cooling fan stops working unknown to you.   You mentioned storing a spare gasoline can in the same area  -  I would keep gas cans as far away from heat and ignition sources as possible, ideally in a well-vented and accident-resistant compartment.

John   
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« Reply #5 on: April 28, 2013, 07:46:33 PM »

Out the back and under the bumper with a little bit of pipe to be blowing the exhaust away from the bus.  Make sure that it is far enough away from your cooling fan that exhaust would be be pulled back.  From the little bit I saw of it, it looks like the bus is in nice condition.
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« Reply #6 on: April 28, 2013, 09:20:02 PM »

How about engine air intake problems being in an open "container" like that?  Will that be an issue for him driving down the road?
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« Reply #7 on: April 28, 2013, 09:23:45 PM »

Run it out the back and by all means use the Venturi stack when camping. You don't want those raw un catalyzed gasoline exhaust fumes near the ground. I think you're going to have overheating problems with that genset though. Onan uses vacuflo cooling-sucking the air over the engine then blowing the hot air out of the compartment. Cheap generators sound good on paper and your wallet-but there's nothing like a well designed RV genset. After you get tired of trying to make this gen work, spend the money and get a good, reliable water cooled Diesel genset. You basically run it for hundreds of hours without thinking about it.

When I was running cross country with my Onan 6.5 Emerald Commercial, at night, I would put a 20" box fan outside to blow the exhaust fumes away from the truck. Got many questions about the fan-but it worked well. Good Luck, TomC
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RJ
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« Reply #8 on: April 28, 2013, 11:29:59 PM »

Mike -

Nice video!  Worth the effort to supplement your question.   Grin

I agree with Clifford & JC: 90o down and 90o out.

I would angle it in such a way that it comes out at the corner of the coach - right where the rear bumper curves around to meet the rear side rub rail.  Keep the extension to no more than a couple inches beyond the rub rail, that way you can easily set it up for a "genturi stack" while parked.  Might also consider some type of quick disconnect from the mounted exhaust if you wanted to use the genset somewhere other than the coach.

Oh, and by all means, keep a spare gas can OUT of the engine compartment!  That's a disaster just waiting to happen!

Tom's point is well-taken.  This little unit may be a good "starter" set to get you going, but long term you'll be happier with a liquid-cooled diesel unit.

FWIW & HTH

 Wink
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RJ Long
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« Reply #9 on: April 29, 2013, 05:51:43 AM »

I have a 3500 watt gene on a roll out dwr right at the same side door you have . Raised up 12" off the floor with a 2 1/2" tail pipe that exits out the right eng. door .I used rad hose 3" long at each end to adjust for vibrations at gene, back door .Cut a s steel vent in the back door ,all the tail pipe raises up from start to end .Had to use 1 90 deg. bend at the back of the gene.There is no conection to the gene or the back door.I have the gene running when driving when using the a/c unit .  I store a 2 gal. gas can up front under the driver in the lower front driver side door straped to the inside wall. I have used this for 7 years ,I get about 9 hrs on a tank of gas (1.85 gal. )   The only problem I have had is the gas will only last about 1 year ,I don't use the gene that much.     
 dave
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1990 mci 102c  6v92 ta ht740  kit,living room slide . home base huntsville ontario canada
Scott Bennett
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« Reply #10 on: April 29, 2013, 12:59:04 PM »

I'm gonna say it...whatever you do, get a CO detector...better yet, get two. Plug them in, in your bedroom...with genset exhaust that close to your sleeping quarters, I wouldn't take any chances. Our genset sits in the old A/C condensor bay under the drivers' seat area (just behind) and when we are stopped for any length of time, my CO detector goes off...and we've routed our exhaust well.
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Scott & Heather
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« Reply #11 on: April 29, 2013, 02:20:06 PM »

If your co detector goes off I would stop the bus and seal up all the leaks before a bigger problem starts       dave
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1990 mci 102c  6v92 ta ht740  kit,living room slide . home base huntsville ontario canada
HB of CJ
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« Reply #12 on: April 29, 2013, 05:52:12 PM »

They run fine if left out in the open.  Less fine if placed in some large enclosed space like a garage.  They do not run well at all when confined in some RV gen space.  Overheating big time.  Sad, but true.

The solution is to get a regular RV gen set designed and intended to be placed in some very tight space.  Even then they must face the right direction and have space and air for cooling.  HB of CJ  (old coot)
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Midwilshire
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« Reply #13 on: April 29, 2013, 06:22:15 PM »

Many thanks for the good ideas.  I think I have enough to go on to complete the project.  But before I get started I'm curious if you think I'm going to have problems with heat generated by the 8V71 - even if only transporting the generator.  The pictures below show where the generator sits and that it is 4" from the exhaust manifold thingy.  Will this proximity cause my nylon straps or the plastic generator housing to melt while bounding down the highway? 








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Michael & Gigi
1978 MCI-5C "Silverliner"
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« Reply #14 on: April 30, 2013, 03:44:35 AM »

To answer the heat question I'd probably mock up something expendable (wood block or something) to sit as far from the exhaust as your generator will. Then I'd drive 30-40 miles and hit it with an IR thermometer to see what kind of heat we're talking about. I seem to recall that the exhaust manifolds on my 8V-71 get about 175 or so. Yours may be different.

If you have overheating problems back there, drop me an email. I installed my 6K diesel air-cooled genny in one of my bays (despite  assurances that it couldn't be done) and it works great. I'll spare you the whole thing for now, but basically I have two fan systems in the bay. One sucks air through the compartment to scavenge heat and carbon monoxide out. With the other, I actually fabricated an air plenum that is attached to the side of the generator itself. I attached a furnace blower (to be able to handle the heat) to that, and it's ducted through a foil dryer hose out of the compartment. On a 90 degree day under load, the temp in my compartment only rose one degree after 30 minutes. Of course the exhaust runs out of the compartment too in its own plumbing.

I've got the generator out of the bus right now to soundproof the compartment, but I'll post some pics if you're interested.
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