|
03-24-2019, 03:12 AM
|
#1
|
Bus Nut
Join Date: Jan 2016
Posts: 253
|
Thinking outside of the (engine compartment) box
In the past decade, anytime I am in the presence of diesel mechanics, I always ask them the same question " which engine is best for a type D bus?" They will often answer "none" because they feel there is not adequate cooling in the engine box. Are there any good solutions for this?
|
|
|
03-24-2019, 03:30 AM
|
#2
|
Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,762
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
|
Quote:
Originally Posted by pengyou
In the past decade, anytime I am in the presence of diesel mechanics, I always ask them the same question " which engine is best for a type D bus?" They will often answer "none" because they feel there is not adequate cooling in the engine box. Are there any good solutions for this?
|
Rear engine buses have the most cooling issues.
|
|
|
03-24-2019, 05:49 AM
|
#3
|
Bus Nut
Join Date: Jan 2016
Posts: 253
|
Quote:
Originally Posted by EastCoastCB
Rear engine buses have the most cooling issues.
|
Has anyone ever though of putting a radiator on the roof directly above the engine compartment
|
|
|
03-24-2019, 09:52 AM
|
#4
|
Bus Crazy
Join Date: Oct 2017
Posts: 1,222
Year: 1999
Coachwork: BlueBird
Chassis: TC1000 HandyBus
Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
|
Quote:
Originally Posted by pengyou
Has anyone ever though of putting a radiator on the roof directly above the engine compartment
|
At one time I wanted to put a Nissan L6 motor from a 280Z into my 1984 pickup and replace the L4. To squeeze it in, I was thinking of the radiator on the roof.
Then I bought a Weber carb and an aftermarket long-pipe exhaust header, and I never looked back. She would easy crawl up a 45° incline at 600 RPM with my foot barely on the gas pedal, and I could just feather the gas even at that low RMP, and she would pull strong.
|
|
|
03-27-2019, 03:23 PM
|
#5
|
Skoolie
Join Date: Mar 2018
Location: Fingerlakes region NY
Posts: 204
Year: 1999
Coachwork: AmTran/Wolfington
Chassis: 3800
Engine: International DT466E 190HP variant
Rated Cap: 72 pax 29500 GVWR
|
You could do it sure. Just would need to build some sort of shielding and housing for it and the hoses. But ductwork underneath the bus might be a good alternative, or even locating the rad to the front if possible!
|
|
|
03-27-2019, 08:21 PM
|
#6
|
Bus Nut
Join Date: Jan 2016
Posts: 253
|
Quote:
Originally Posted by WARGEAR
You could do it sure. Just would need to build some sort of shielding and housing for it and the hoses. But ductwork underneath the bus might be a good alternative, or even locating the rad to the front if possible!
|
The front was my first thought - especially since I could tap into the line for heating, but it would mean a 30+ foot long tube for the antifreeze to run through, and then 30' back. On top of the bus would only be about 9 feet and could be run through the passenger compartment in the corner - well insulated and protected. Is the length a valid fear? Given the brick shape of busses, I think air flow would be better on top of the bus than plastered on the front of the bus. Lay the radiator flat on the roof, but elevate the rear 4-5"....build a simple vented enclose around it. The sun might heat the fluid up to 130 degrees when parked, but in the big picture, this is insignificant to the engine operating temperature.
|
|
|
03-27-2019, 08:31 PM
|
#7
|
Skoolie
Join Date: Mar 2018
Location: Fingerlakes region NY
Posts: 204
Year: 1999
Coachwork: AmTran/Wolfington
Chassis: 3800
Engine: International DT466E 190HP variant
Rated Cap: 72 pax 29500 GVWR
|
You need to consider the volume that would require pumping. The water pump would need to be strong enough to go upwards and around. If it’s front mounted the length isn’t a concern really. Many of our buses had inside heaters very far from the engine and rad. Same exact concept.
|
|
|
03-27-2019, 11:00 PM
|
#8
|
Bus Nut
Join Date: Jan 2016
Posts: 253
|
Quote:
Originally Posted by WARGEAR
You need to consider the volume that would require pumping. The water pump would need to be strong enough to go upwards and around. If it’s front mounted the length isn’t a concern really. Many of our buses had inside heaters very far from the engine and rad. Same exact concept.
|
Would an auxiliary electric water pump be useful? Maybe I am overly paranoid but I am concerned also about the physical safety of a radiator up front..minor fender benders...people backing up, etc. although it would be really cool - but time consuming - to build a "nose" for a type D pusher bus...to help some of the aerodynamics
|
|
|
03-27-2019, 11:26 PM
|
#9
|
Bus Nut
Join Date: Jul 2017
Location: Rapid City, SD
Posts: 993
Year: 2001
Coachwork: Blue Bird
Chassis: CS RE
Engine: ISC 8.3 L 260 hp
Rated Cap: 36
|
Biggest problem with RE bus cooling is getting the air across the radiator. A lot of HP is used for the cooling fan. If putting a radiator on the roof it would work best to use a short radiator mounted vertically across the width of the roof with a scoop to direct the air through the radiator. Mounted horizontally electric cooling fans would be needed like a roof mounted AC condenser.
Ted
|
|
|
03-28-2019, 04:27 AM
|
#10
|
Bus Nut
Join Date: Jan 2016
Posts: 253
|
Quote:
Originally Posted by TJones
Biggest problem with RE bus cooling is getting the air across the radiator. A lot of HP is used for the cooling fan. If putting a radiator on the roof it would work best to use a short radiator mounted vertically across the width of the roof with a scoop to direct the air through the radiator. Mounted horizontally electric cooling fans would be needed like a roof mounted AC condenser.
Ted
|
Thats what I was thinking - a 6 or 7' wide radiator mounted across the width of the bus....raised 4-5" in the back with some kind of shroud/scoop to direct more air to it..and a fan (probably a couple of fans) to provide air at lower vehicle speeds. I may have to use 2 radiators - I have not seen a 7' wide radiator.
|
|
|
03-28-2019, 08:35 AM
|
#11
|
Bus Crazy
Join Date: May 2015
Location: Central Tx.
Posts: 1,907
Year: 1999
Chassis: Amtran / International
Engine: DT466E HT 250HP - Md3060
|
Just a thought but...what about installing a pair of high cfm electric fans?
|
|
|
03-28-2019, 08:36 AM
|
#12
|
Bus Geek
Join Date: May 2014
Location: West Ohio
Posts: 3,660
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
|
If you're relocating the radiator, it would cool better being mounted on the front. Air pressure would be highest there vs being mounted on the roof and you'll actually have negative air pressure if you mount it in some spots.
You could rig up a few electric fans to be behind it in place of a hydraulic or mechanical fan. Biggest issue would be running 30 ft of pipe to and from the radiator and keeping it all from leaking. Your mechanical water pumps can put out a lot of pressure. Try dead heading the upper radiator hose sometime with the thermostat removed.
|
|
|
03-28-2019, 09:06 AM
|
#13
|
Bus Geek
Join Date: Dec 2016
Location: Weeki Wachee, FL
Posts: 3,056
Year: 1997
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: Cummins 5.9
Rated Cap: 72
|
The Britten V1000 motorcycle placed its radiator under the seat and used ducts to move air to it, claiming a reduction in drag without loss of cooling performance. it stands to reason that you could put the radiator anywhere as long as you too crate a duct system to move air. However, given the aerodynamic realities of a transit style bus, it seems unlikely that you'd gain anything by relocating it.
|
|
|
03-28-2019, 11:28 AM
|
#14
|
Bus Nut
Join Date: Sep 2017
Location: Damascus, OR
Posts: 681
Year: 2004
Chassis: International
Engine: T444e w/ 2000 Allison Trans
Rated Cap: 35
|
what about a large scoop or fin to divert air into where it is needed?
|
|
|
03-28-2019, 12:00 PM
|
#15
|
Bus Crazy
Join Date: Oct 2017
Posts: 1,222
Year: 1999
Coachwork: BlueBird
Chassis: TC1000 HandyBus
Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
|
A radiator on the roof in a closed loop has a siphon-effect as the coolant returns down to the engine, and has no bearing on the pump. For every ounce of coolant missing in the top of the radiator, load is added to the pump. So it seems to me.
My air conditioning would cool so much better when my vehicles' AC radiators were not in the sun. Any shadow made them work so much better. The rooftop AC radiators on my bus were sun-exposed, and are getting new metallic shade-covers. If they work up there, so should your rooftop one. But I hate the added height (but love the AC) so I would put the engine radiator in the front, if it added overall height to my bus.
Negative pressure is, as mentioned above, always a possibility, especially if the engine radiator will be placed behind something else on your roof, i.e. an AC radiator setup, a roof-rack full of stuff, etc.
|
|
|
04-07-2019, 03:16 AM
|
#16
|
Bus Crazy
Join Date: Jul 2011
Location: Winlcok, WA
Posts: 2,233
|
Every OEM that has ever built a rear engine bus has tried all sorts of ways to cool a rear engine bus. Suffice it to say, no one has been 100% successful. If you drive a rear engine bus it isn't a question of if you are going to overheat so much as when you will overheat.
Flxible, Kenworth, Gillig, and MCI all tried some sort of roof mounted scoop to force more air across the raditor.
Crown solved the problem with their mid-mount engine by using a radiator that is 3' tall, 6' wide, and at least 8" thick.
Setra tried solving the problem by adding additional radiators for greater cooling ability.
The basic problem with cooling a rear engine bus is you are working against physics. The air along the outside of the engine compartment when you are going down the road is a low pressure area. The engine compartment is a high pressure area. Moving air "uphill" to go across the cooling fins of a radiator takes a LOT of HP. Whether it is directly off of the engine via a belt or hydraulics or a passive system using just electric fans it is going to take 35-40 HP to turn the fans enough to cool the engine.
The problem exacerbates exponentially when you start to boost the HP and you keep your foot buried as you go up a hill.
Moving the radiator to the front bumper so the air the bus is pushing through will have to push through the radiator is probably the best way to never overheat. But at that point you are relying on pumps and electric motors to keep the coolant cooled and circulating enough to keep the engine cool. VW had a lot of problems with their water cooled rear engine Vanagons because the coolant circuit was prone to getting air locks.
|
|
|
02-25-2020, 11:25 AM
|
#17
|
New Member
Join Date: Feb 2020
Posts: 6
|
Hello,
I would think there must be solutions to the problem of over heating and horse power robbing, I’m considering this and would love to hear some feedback on the following....
1. Considering radiator construction is a finned set of copper tubes soldered/brazed together and the existing heater in the front of the bus is already an extension of the radiator cooling system, why not run commercial grade 3/4” to 1” copper pipes from back to front of the bus via quality shock absorbing mounts, to a front mount fabricated radiator? This is about the same distance as the coolant travels in the existing heater and should result in positive results=Obvious increased radiator cores and surface, as well as significant coolant volume increase(always good), and the copper pipe traveling supply/return up to 80’ in length will certainly shed a lot of heat along the way! You could even strategically add base baseboard heating fins throughout the pipe to further cooling? https://www.parksupplyofamerica.com/...oard-Element_3
Also to alleviate parasitic HP loss from a belt driven fan, the addition of a serious electric fan in lieu of a belt driven fan could be an option? I know from my street rod days that there are some serious electric fans available that can move some very serious amounts of air.
Thoughts?
|
|
|
|
Thread Tools |
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|