Radiator fan consumes over 10% of engine HP!

[Kenny]

This may be of some use relating to most aspects of engine cooling systems.

http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm

Kenny

[belfert]

I have a Dina that has a side radiator.  Based on my trip to Florida this past winter I don't know that a side radiator gets any less salt exposure.  My intercooler is all white after that trip and I assume it is a layer of salt.  

MCI's side radiator design is probably different than Dina so salt exposure may be less.

I would guess that the overhead radiators are easier to work on than my radiator that is jammed between the engine and the sidewall.  It was a bitch to replace in 2007.  I have to pull the intercooler today to replace the water pump, but it is easy to get out.

[RJ]

On the E and J models, do the fans blow air out the side or suck it into the compartment?  Is the compartment ducted separate from the engine area?

Brian -

To answer your question, the fan draws air thru the radiator and dumps it into the engine compartment - just like 90% of the rest of the industry with side-mounted radiators.

Very few bus manufactures side mount the radiator, then use sheet metal ducting to a fan running in parallel to the engine's crank pulley.  Early Gillig skoolie pushers and some Flxible hi-way models come to mind, there are others.

GMC's V-drive allowed the fan to be directly driven w/o any belts/pulleys/miter boxes, etc.  Some late production 4104s, and all V-block engines (transit or highway models) incorporated a torus drive to "lock up" the fan when increased engine cooling was called for. 

GMC was also the first coach manufacturer to utilize the full-width air dam ("mud flap") behind the rear axle to create a low pressure area under the engine compartment to help draw the heated air out from under the coach.  Crown & Gillig used a similar air dam behind the front axle on their mid-engine models.

I remember reading somewhere that MCI originally mounted the radiators up high like they did to prevent the frequent slushy conditions found in Canada from plugging up the cooling system.  Don't know how true, but it's possible.

FWIW & HTH. . .

[belfert]

Dina has the radiator parallel to the crankshaft pulley between the engine block and the side of the bus.  This is t-drive.  The fan is run off the crankshaft pulley.  There is a rather large kind of a tunnel on the side of the bus at the rear to supply cooling air.

I have attached pictures of the tunnel and the radiator.

[Bob Belter]

Ahoy, Bus Conversion Folks,

My -01 Eagle has a Cummins M-11 and Roadranger 10 spd.  My radiator is ~~25% bigger than the already big Eagle unit, and my fan is a 12 bladed 34" aerodynamic unit, properly shrouded.   My first engine was a 6V-92T, but this Cummins engine is very cold blooded.

I had installed a fan drive 'overdrive' unit on my -01 Eagle. It is a Laycock Overdrive J Type  S/N 27 115895 038537. It is derived from a '1980's Volvo Laycock transmission overdrive unit.  Has a 26% speed-up in overdrive, to run the fan 26% faster.  There are a number of mods to permit installation in a bus as a fan drive.  It was NOT easy to build.   An electric solenoid valve on the case puts it into overdrive, with a temp switch on the engine to do it (plus a manual driver's switch). 

This thing started life behind a sort of anemic Volvo engine, but it looks just like the ones behind the Dodge Cummins diesels, so it is likely to last a long time just running a fan.  The mods are ordinary machining which are not likely to fail, and are easily re-done if needed.  The rest of it consists of replaceable Volvo parts.

YEARS later, and the overdrive had NEVER turned on by itself.   The large radiator and the very efficient fan resulted in a cooling package which was 'off-the-bottom' of the cooling horsepower map.  I only run that fan at 61% of crankshaft  speed, and I was doing some re-arranging so I removed the unit.  I do get such good fuel mileage on my Eagle that I'm careful not to mention it around guys with DD-8-V92/old Allison's for fear of a 2x4 upside the head!

Here are some 'gee-whizz' equations having to do with fans/propellers.
As you can see, Power is a cube function of RPM, and Diameter, while flow-Q is only a direct function.   So—speeding-up the fan is a lousy way to get more cooling.  It costs you a lot of power, which does NOT help the wheels to go around.               
           

A bigger radiator, (or a supplemental) plus a large and efficient fan is much better.  I understand that 'misting' is very effective, but is you don't use distilled water, you will 'lime' the radiator.   Sort of like peeing in bed to get warm.

I have listed this fan overdrive unit for sale from time to time, but no takers.
If you wish, I can forward high res pix -- big files.   Please ask at:  rhbelter@comcast.net     or ph 831 625 0670

Enjoy   /s/   Bob

[Bob Belter]

Ahoy, Bus Conversion Folks,

Sorry to do a 'double' post, but the equations did not come through.
They are there now.

My -01 Eagle has a Cummins M-11 and Roadranger 10 spd.  My radiator is ~~25% bigger than the already big Eagle unit, and my fan is a 12 bladed 34" aerodynamic unit, properly shrouded.   My first engine was a 6V-92T, but this Cummins engine is very cold blooded.

I had installed a fan drive 'overdrive' unit on my -01 Eagle. It is a Laycock Overdrive J Type  S/N 27 115895 038537. It is derived from a '1980's Volvo Laycock transmission overdrive unit.  Has a 26% speed-up in overdrive, to run the fan 26% faster.  There are a number of mods to permit installation in a bus as a fan drive.  It was NOT easy to build.   An electric solenoid valve on the case puts it into overdrive, with a temp switch on the engine to do it (plus a manual driver's switch). 

This thing started life behind a sort of anemic Volvo engine, but it looks just like the ones behind the Dodge Cummins diesels, so it is likely to last a long time just running a fan.  The mods are ordinary machining which are not likely to fail, and are easily re-done if needed.  The rest of it consists of replaceable Volvo parts.

YEARS later, and the overdrive had NEVER turned on by itself.   The large radiator and the very efficient fan resulted in a cooling package which was 'off-the-bottom' of the cooling horsepower map.  I only run that fan at 61% of crankshaft  speed, and I was doing some re-arranging so I removed the unit.  I do get such good fuel mileage on my Eagle that I'm careful not to mention it around guys with DD-8-V92/old Allison's for fear of a 2x4 upside the head!

Here are some 'gee-whizz' equations having to do with fans/propellers.
As you can see, Power is a cube function of RPM, and Diameter, while flow-Q is only a direct function.   So—speeding-up the fan is a lousy way to get more cooling.  It costs you a lot of power, which does NOT help the wheels to go around. 

P1/P2 = (N1/N2) cubed
P1/P2 = (D1/D2) cubed
Q1/Q2 = (N1/N2)

A bigger radiator, (or a supplemental) plus a large and efficient fan is much better.  I understand that 'misting' is very effective, but is you don't use distilled water, you will 'lime' the radiator.   Sort of like peeing in bed to get warm.

I have listed this fan overdrive unit for sale from time to time, but no takers.
If you wish, I can forward high res pix -- big files.   Please ask at:  rhbelter@comcast.net     or ph 831 625 0670

Enjoy   /s/   Bob

[pvcces]

Thanks, Bob.

We had learned some of the same things that you are talking about, and being interested in fuel economy, we looked for something similar in our boat.

It is a 40 ton, 62 foot ex drum seiner, and it has a propeller of nearly four feet in diameter. When the hull is clean, she runs right at 6 knots and burns about 2 gallons per hour. If we had a propeller of only two feet, we would have played hell getting the fuel consumption down to 4 gallons per hour.

FWIW

Tom Caffrey

[JohnEd]

Guys,

I have read almost all of these suggestions in various threads all over this forum.  I think every blessed one of these current suggestions is a must for the DD 2 stroke.  One thing I think is missing from all this is a recommended solutions/implementation train of thought.  If I miss anything or you think I am out of sequence please holler for everyone's sake.  I am tough skinned.

Priority of implementation is driven by our wallets to a large degree and "ease" of install is a significant driver.  The easy stuff is also the cheapest.

1.  Install that "mud flap" across the rear axle.  Mill supply outlets throw away gobs of this stuff all the time.  It is remnants of conveyor belt and nothing that bends easily is tougher.  I install the thing too long and let it "wear" itself on to the "purfeK" size.  This cost nothing to operate and is free if you know which dumpster to peruse.  Life span?   Ha!

2.  This wasn't mentioned.  Install a 1 inch lip that is perpendicular to the bus on the leading edge/corner of the rad opening.  This edge disrupts the flow of the air across the opening and creates a slight vac directly behind it that turns the air into the opening.  I would use a piece of 1/4 inch aluminum flat stock and pop rivet it to the inside edge of the rad opening.  A strip of PVc or just about anything will work.  This won't do much but it is free to operate and will never wear out.  And invisible to the untrained eye.

3.  Air scoops are a fraud in my opinion but I have never talked to anyone that had them.  Measure the total sq inches of opening with out them and then measure the opening that isn't shrouded by them and add the sq inches of the lead opening.  I know there is some ram air but I think the thing is too small to pencil out.  Easy install though.

4.  Ditch that mud flap across the back.  It hurts the cooling so less is better with that gone.  Might be of sufficient dimension to use after the axle.


Expensive stuff:

1.  If you don't do anything else....shroud that fan.  The efficiency of the fan is really improved by a shroud.  This one up grade may solve your overheating problem.  It will help any generation fan.

2.  Install a modern high efficiency molded fan blade assembly.  That antique thing with bent sheet metal blades is a power robbing sucker.  DC should pass a law and make everybody install these....not really but I thought I would raise some hackles.

3.  Install a therm fan drive/clutch if you can afford it.  It will really only come into play after you have "over-designed" the rest of the system.

4.  Install that expensive ceramic cloth insulation on the exhaust manifolds, piping to the turbo, the turbo drive impeller, exhaust piping running between the muffler and the turbo.  This will increase your max HP and efficiency.  Not to mention dropping you engine bay temp dramatically.  And an engine running in a lower ambient will also need less cooling.  Engine oil should run cooler for that reason alone.

5.  Install an over-sized radiator.  That may be a challenge for a worn 2 stroke but it will last forever.

6.  Rad misters do work but I think they are a band-aid that should last till you get the rest of the  system fixed.

7.  If you could possibly take advantage of ram air from a roof scoop or front mounted rad you will save serious money if you couple that with a clutched fan.

8.  I have water injection on my 440 but it's there to allow more spark advance running on regular.  It does also lower engine temp and sheds heat better out the exhaust.  There is some small increase in power and efficiency.  Mine only activates under heavy load.  I think these systems are sold for D engines.

anything else?   Guys?

John

[luvrbus]

Makes sense to me 6 knots that is about Bob's highway speeds lol 2 gals a hour I could use my boat more often with that fuel usage beats the hell out of + 50 gals per hour

good luck  

[artvonne]

It is a 40 ton, 62 foot ex drum seiner, and it has a propeller of nearly four feet in diameter. When the hull is clean, she runs right at 6 knots and burns about 2 gallons per hour. If we had a propeller of only two feet, we would have played hell getting the fuel consumption down to 4 gallons per hour.

FWIW   Tom Caffrey   

Proves the old theory that its more efficient to move a large volume of fluid slowly, rather that a small volume of fluid rapidly. That kind of fuel burn in that large of boat is pretty amazing.

  Its interesting that most of the electric radiator fans have plastic molded fan blades that are actually pretty decent looking fan blades. I keep looking at the squirell cages and gear box on the MCI and while I know everyones opinion, it just all looks terribly, incredibly power robbing ineficient. It may very well pull 50 HP off the engine at full speed, but I am not convinced it provides 50 HP of cooling.

  John, if a 1 inch lip on the leading edge of the radiator opening did anything, then I believe a NACA duct ahead of the opening, with the opening boxed, so all intake air fed to the radiator comes from the NACA duct, would do a LOT more.

  With the opening boxed, getting the grill out of there could also help air flow. I had a satelite dish with 1/4 inch mesh. The manufacture (Paraclipse) claimed that above 30 mph the wind saw the dish as a solid disc. Another impediment to flow are the air louvers. Or, replace the grill with aerodynamic vanes.

  Perhaps with enough work done to increase natural air flow, a couple of BIG electric fans could work? Or perhaps, a different fan arrangement. Anyone ever think of removing the squirell cages, extending the shafts of the miter box (after remounting it up higher) and driving shrouded prop fans directely behind the radiators?

[RJ]

Anyone ever think of removing the squirrel cages, extending the shafts of the miter box (after remounting it up higher) and driving shrouded prop fans directly behind the radiators?

Paul -

Don't remember where I read it, but IIRC, squirrel cage fans move more air for their size than a prop fan.  I think the factor was 3x or 4x more.  They're very efficient, comparatively.

FWIW & HTH. . .

[luvrbus]

Paul saw a MCI 5 few years ago at the rally in the caverns the guy removed the mitre box and used one of the air conditioner blower motor with shafts going to each side with belt driven fans on each radiator he said it worked who knows the bus was for sale and some owners are like some truck drivers when it comes to things that work.
If you go to the BNO board check out Boomers electric fan in a Eagle his system works 

good luck

[artvonne]

  If the AC fan motor could run two belt driven fans, then the AC motor could likely drive the current centrifugal fans more efficiently. Maybe the stock setup isnt pulling as much power as thought, its just got way oversized components.

[JohnEd]

  John, if a 1 inch lip on the leading edge of the radiator opening did anything, then I believe a NACA duct ahead of the opening, with the opening boxed, so all intake air fed to the radiator comes from the NACA duct, would do a LOT more.

Do you have a pic or a drawing of what you are talking about?  NACA isn't in my vocabulary.  A  link would do it as well.  Thanks


  Perhaps with enough work done to increase natural air flow, a couple of BIG electric fans could work? Or perhaps, a different fan arrangement. Anyone ever think of removing the squirrel cages, extending the shafts of the miter box (after remounting it up higher) and driving shrouded prop fans directly behind the radiators?

You can't get away from the 50HP worst case max load requirement.  Imagine the size of a 50HP electric motor.  Even a 25 or a 15.  I am amazed that this topic names people that are supposed to have done it.  And I am NOT calling anybody a liar.  How many HP is the fan that drives the stock air conditioning?

A bladed fan drops all of its air moving ability with just a little back pressure.  A shrouded blade is more efficient than a SC only if there is no back pressure.  BUT, let there be a little back pressure and the SC passes the bladed fan right up in performance.  A little more back pressure and only a SC can move any air at all. The MCI has tiny rad openings and the rads are thick with cores that resist air flow and that's why they used the SC.  Pushing air through all that AC ducting also requires a SC.

John

[artvonne]

  John, you see those big scoops on some of the MCI's. Some say they dont work as well as they appear, the theory is much of the air simply spills around them rather than going in. Air is wierd stuff, and doesnt well follow the way our minds think it would. Cylinder head porting is a good example, you see people open up intake ports and smooth the walls, but testing often shows they flow "less" air.

  One of the problems with Buses and rear radiators, and the MCI's particularly, may be the opening is too close to the rear corner; there is likely a great amount of turbulance there, and probably is not the best place, from an aerodynamic standpoint, to put an air intake. If air is trying to suck around the corner, its going to increase with speed and would follow Cliffords contention that they take more power with speed.

  You asked about the AC fan. The condensor fan on the 9's are 24 volt DC, 2 HP, the HVAC fan is 1.5 HP. If someone was able to use one of those back there and got adequate cooling, even after adding belt drives further robbing power, then the stock system is either not pulling the power some claim, or its woefully inefficient. In either case, just because it uses a 50 HP rated belt doesnt mean its drawing 50 HP. Its just as likely its overbuilt for endurance.

  So the best place to take in air is in an area with higher pressure and more laminar flow, which is likely going to be somewhat forward of the present air intake. The next obstacle is how to get the air to enter as freely as possible without slowing it down or disrupting air flow. If it slows down to where air starts spilling over the vent, either the intake is too large, or the exhaust end isnt venting fast enough (not enough negative pressure), in either case its defeating the purpose.

  Here is a primer on NACA ducts:
  http://en.wikipedia.org/wiki/NACA_duct

  Here is a schematic:
  http://images.rcuniverse.com/forum/upfiles/463007/xv63751.jpg

  Like I say, I think one could be fabbed out of cardboard, and with some manometers a guy could figure out the best placement, size, etc.. If it wont work, squish it and toss it, no harm done. If it works, a pair could easily be fabbed out of aluminum and riveted/glued, etc., to the Bus.

  Some dont like rivets, want the clean side skin so it looks RVish. Im sure others would see a big NACA duct plastered to the side of a Bus as pretty ugly. But some see the Ferrari F-40 as ugly, and others see it as beautiful. Aerodynamics is often only seen as pretty by gearheads and airplane fanatics.

  With enough airflow, electric fans could augment when needed, and not run at all at highway speed.