Reply
 
Thread Tools Display Modes
 
Old 03-15-2017, 08:58 PM   #1
New Member
 
Join Date: Feb 2017
Posts: 8
Why 2 engines

Ok, I know why i have 2 engines on the bus. One is for the Driving of the bus and the other appears to power the AC on this 1988 Chevy Thomas School Bus with a 366 v-8 and a driver side under the bus mounted inline 4 cylinder. But why and are they that good for AC anymore? I would like to know if anyone knows anything about servicing this engine and/OR is there away to convert this to an onboard Generator to power the buses electrical needs. Desperately seeking advise. Do i rip out every thing or keep the engine? Thanks peeps.
b12lewis is offline   Reply With Quote
Old 03-15-2017, 09:17 PM   #2
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 6,366
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
I would keep it!!.. you now have A/C for when you are parked.. thats usually the Biggest user of electricity when boondocking there is...

slap a 200 amp alternator or 2 on it ( if it doesnt already have one), an inverter or 2 and now you have 110 volt AC power from it.. ill bet that engine can easilt run your air-conditioning and at least 1000-1500 watts of power.. I doubt you'll need more than that?

I know others will tell you to rip it out and put up solar or some other fancy stuff.. and get rid of the A/C.. (this crowd seems anti A/C).. but id keep it, modify it and use it, its already there.. you dont have to buy or retrofit anything to use it..
its something i could only wish I had in my bus..
-Christopher
cadillackid is offline   Reply With Quote
Old 03-15-2017, 10:06 PM   #3
Bus Crazy
 
somewhereinusa's Avatar
 
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 1,570
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Her, me and Molly
I would definitely keep it. Do like Cadillac kid said.
somewhereinusa is offline   Reply With Quote
Old 03-15-2017, 10:18 PM   #4
Skoolie
 
Join Date: Dec 2016
Posts: 123
I don't know anything about that particular secondary engine, but it sounds like a great find. As long as it works or can be repaired, you can probably hook up an alternator to it and generate power. You might want to look at some of the old designs made by people who created brackets to attach alternators to lawn mower engines and other such miscellaneous sources. Folks in the self-sufficiency business have been rigging generators out of anything that can produce rotational force for decades, so there's definitely a way to do it - it just might take a little inventiveness to machine or source the parts you need.
lucasd is offline   Reply With Quote
Old 03-15-2017, 10:24 PM   #5
Bus Nut
 
Join Date: Jun 2016
Location: Orange County, CA
Posts: 325
Year: 1990
Coachwork: integral
Chassis: Crown Supercoach II
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
And from a committed solar proponent, I also say keep it! Do as Christopher says, put a big 12VDC alternator on it, and also a 120 VAC alternator, then you've got the same as a modern truck APU but for a fraction of the price. GM 4104 buses in the 1950s used a small gasoline engine for their A/C, so you're in good company. Later on if you want to add solar (and why not?), you've now got your back-up Plan B for when the sun's not shining.

Another option for a gasoline engine, especially one that may not be used much, is to convert it to propane. Assuming you'll have propane on board anyway for cooking and heating, you'll have a fuel that never goes stale and gums up the carburetor, like can happen to infrequently-used gasoline engines.

John
Iceni John is offline   Reply With Quote
Old 03-15-2017, 10:33 PM   #6
Skoolie
 
Join Date: Dec 2016
Posts: 123
Quote:
Originally Posted by Iceni John View Post
And later on if you want to add solar (why not?), you've now got your back-up Plan B for when the sun's not shining.
Precisely. A small motor coupled to a hefty DC alternator makes a great source for charging a battery bank if your sun intake has been low. It's more efficient for that purpose than charging from a typical generator. It's similar in concept to the more costly "inverter generators" that are sold in that it creates DC as its primary output and only produces AC by way of an inverter stage.
lucasd is offline   Reply With Quote
Old 03-16-2017, 12:18 AM   #7
Bus Nut
 
Join Date: Jun 2016
Location: Orange County, CA
Posts: 325
Year: 1990
Coachwork: integral
Chassis: Crown Supercoach II
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Quote:
Originally Posted by lucasd View Post
Precisely. A small motor coupled to a hefty DC alternator makes a great source for charging a battery bank if your sun intake has been low. It's more efficient for that purpose than charging from a typical generator. It's similar in concept to the more costly "inverter generators" that are sold in that it creates DC as its primary output and only produces AC by way of an inverter stage.
In theory maybe, but in practice you'll still want to charge them through a proper 3-stage (Bulk, Absorb, Float) temperature-compensated charger set to exactly the voltages and times your specific batteries need for a correct charge. Just pumping 12 volts into them is like using an old-fashioned unregulated 'charger' or converter - they can easily boil batteries dry, or not charge them enough. Technology has progressed far since those days, and batteries will benefit from modern charging protocols.

John
Iceni John is offline   Reply With Quote
Old 03-16-2017, 01:02 AM   #8
Bus Crazy
 
Join Date: Jul 2011
Location: Winlcok, WA
Posts: 1,549
Most coach A/C systems take 10-40 HP to operate. The range covers the different sized systems.

It takes a lot of HP to turn compressors and alternators that are working harder to support the added strain of condenser and evaporators fans. Many buses have an additional alternator that kicks on when the clutch for the A/C compressor kicks on. The additional alternator is dedicated to running just the electrics for the A/C system (which makes troubleshooting a problem if the clutch doesn't kick on).

In your case, while the GM big block 366 gas V-8 is a healthy performer, in a full size bus it has to work really hard just to move the bus down the road or to climb a hill. If you added the additional work to run a coach A/C system the bus would be relegated to slow lane whenever it was running.

Using a pony motor to power the A/C system is a very elegant solution to having A/C and still being able to run highway speeds.

Others have pointed out ways in which to utilize the pony motor for other purposes than just for the coach A/C.
cowlitzcoach is offline   Reply With Quote
Old 03-16-2017, 02:08 AM   #9
Skoolie
 
Join Date: Dec 2016
Posts: 123
Quote:
Originally Posted by Iceni John View Post
In theory maybe, but in practice you'll still want to charge them through a proper 3-stage (Bulk, Absorb, Float) temperature-compensated charger
No one is advocating just pumping the alternator output into batteries directly. That's a great way to boil them dry and ruin them.

Lots of modern generators create DC and run it through an inverter to get AC, which you would then have to feed back through a charger to get DC for charging. My point was that you benefit by not taking that inverter loss if you have a way to just plug straight DC into your charger.
lucasd is offline   Reply With Quote
Old 03-16-2017, 03:33 AM   #10
Bus Nut
 
Carytowncat's Avatar
 
Join Date: May 2016
Location: Richmond Virginia
Posts: 906
Year: 1984
Engine: 366 Big block Chevy! :) w/ Stick shift
John's right

Quote:
Originally Posted by Iceni John View Post
In theory maybe, but in practice you'll still want to charge them through a proper 3-stage (Bulk, Absorb, Float) temperature-compensated charger set to exactly the voltages and times your specific batteries need for a correct charge. Just pumping 12 volts into them is like using an old-fashioned unregulated 'charger' or converter - they can easily boil batteries dry, or not charge them enough. Technology has progressed far since those days, and batteries will benefit from modern charging protocols.

John
Ask me how i know! Charge controller accidentally got set to gel and boiled two trojan deep cycle batteries. They need to be charged correctly or will be easily ruined.

And very cool about the 4cyl generator, also this 366 bbc is a superb motor. Been used in dump trucks and medium duty rigs for quite awhile; simple and easy to work on.
Carytowncat is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 05:23 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.