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Author Topic: Electric Radiator fans for MCI  (Read 6803 times)
TomC
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« Reply #30 on: March 08, 2008, 09:04:16 AM »

Skipn- your hypothesis sound good on paper, but there are still some myths I have to discuss.  Hypothesis 4 is not correct.  Thee only reason that trains use Diesel/electric is that you don't need a transmission or clutch/torque converter to get the load moving.  An electric motor has the neat built in feature that it puts out maximum torque at zero rpm and maximum horsepower at full rpm-just perfect for getting a heavy load moving.  Early Diesels tried the same setup as steam trains, first starting on compressed air then at about 15mph could ignite the engine-but obviously that didn't work.  Running Diesel/electric is inefficient.  First you have the engine driving the generator for about 96% transmission of power.  Then the electricity running through switching and through the electric motors makes for about another 95% efficiency-so you loose about 10% power or fuel burn with a Diesel/electric.  The most fuel efficient is direct drive anything-case in point is the big container ships using a single 2 stroke engine directly (no gear reduction) driving the propeller.  Those big container ships both have the most fuel efficient Diesels made and can move the most tonnage with the least amount of fuel possible.

Makemineatwostroke- in regards to the electric fan buses in China and Spain-I think you'll find that they don't run two stroke engines.  If I put a Series 50 in my bus, I would also feel confident in using electric fans to cool the engine.  But with the combination of our 2 stroke engines, limited radiator size, no frontal air ram like a truck, the most prudent is to stick with the tried and true that is already on the bus.  I have a big 30" 8 blade fan on mine that is direct drive that I know is sucking big time air and horsepower, built for reliability, I'm leaving it be.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
skipn
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« Reply #31 on: March 08, 2008, 09:26:04 AM »

Tom,

   Thank you for your point (well taken) I would like to offer that (if I remember my class days) that
 from engine to wheels there can be a loss of up to 50% of HP. The current set-up on an MCI of belt
 to gear box has to have some loss. The question is is it more than the 10% you stated of electricity
 created and transmitted to be used.   So the real question to start off whith is:

  Is the power loss of a belt system to a gear box greater than 10%.


    Again thanks

    Skip
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makemineatwostroke
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« Reply #32 on: March 08, 2008, 10:02:52 AM »

TomC, the biggest draw back cooling a V series two stroke is the design.You have a water pump on the left side pulling water from the oil and transmission cooler first then you have the crossover pipe pushing 200 + degree water to the right side this system hasn't worked for Cat,Cummins or anyone else with out large radiators and fans.The great part about  removing heat from a 4 stroke you can move the heat with turbo boost won't happen on a two stroke in fact it will make it worse water only for cooling a two stroke Henry Ford had it right on his flat head engines a water pump for each side  

The MCI guys have a problem with cooling because MCI would not give up on their idea about the radiators staying cleaner mounted up high but the problem with this was you had a water pump not design to pump water with a 4 ft head on it and was already at a high temperature from the engine.Water doesn't like to go up hill easy and we tried to tell this to MCI for years but when you have the best selling bus why change also they lose the air movement after certain speeds less air for the fan system to pull into the radiators and I don't know if a electric fan would work on these or not. A simple test for these guys is use a 6 ft long piece of yarn tied to the bus and watch the movement on it at different speeds Buses that have a low and side mounted radiator like yours and other bus are far easier to cool than the high mount systems some manufactures use   have a good day  


« Last Edit: March 08, 2008, 10:29:18 AM by makemineatwostroke » Logged
Lin
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« Reply #33 on: March 08, 2008, 10:40:06 AM »

Is there any value to adding an air scoop to the sides of an MCI?
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« Reply #34 on: March 08, 2008, 11:40:00 AM »

scoops are a benefit,

Other than the exposed are of the low side mount radiator, I do not see any difference between those of GM two storkes and the MCI's high mounts.  why would it be any easier for radiators mounted lower to sucjk air vs those that are high mounted?

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boogiethecat
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« Reply #35 on: March 08, 2008, 12:32:55 PM »

So why doesn't someone just take the RPM reading of one of your squirrel cage fans when your engine is at peak RPM, and then remove the drive to the fan and put a big DC motor on it, run it up and measure the voltage/current (ie horsepower) it takes to duplicate that measured RPM.  In a nutshell all the arguements would become clear as to whether it will or will not work... Maybe we can all place bets... Smiley
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kyle4501
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« Reply #36 on: March 08, 2008, 05:30:50 PM »


You are fortunate in having parts buses. When I looked for a gear box, I knew where there were several scrap 4501s and they were all missing the fan box.


They ain't parts buses, they are still viable buses - except for 011 - If I start removing essential parts, then they will become scrap & there are too few of 'em left as it is.

I know all about the gear box, even talked to Ohio Gear about new gears & shafts. Yep, still available . . . Just the low sales volume means the overhead is placed on fewer parts which translates to higher price.  Cry



If one is going to re-design the cooling system, it occurs to me that there are many things one needs to know, some that come to mind ;
- how much heat rejection is required
- radiator efficiency
- coolant flow rate
- The above are used to determine how much air flow is needed thru the radiator.

I'm sure there are lots more things that will influence the results . . . . . .
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« Reply #37 on: March 08, 2008, 06:19:25 PM »

So why doesn't someone just take the RPM reading of one of your squirrel cage fans when your engine is at peak RPM, and then remove the drive to the fan and put a big DC motor on it, run it up and measure the voltage/current (ie horsepower) it takes to duplicate that measured RPM.  In a nutshell all the arguements would become clear as to whether it will or will not work... Maybe we can all place bets... Smiley

Could the max RPM of the MCI squirrel cage blowers be deduced from the gear ratio of the gearbox and pully drive?  
If the box is 1-1, a tape on the pulleys would give that ratio.  I'll bet the drum RPM is about the same as the engine RPM.  
The CFM of the blowers could be found in an HVAC manual...I'll bet Nick or Christy could offer an excellent idea of what the CFM of a similar sized squirrel cage blower might move.  Multiply times two and we have an idea of the CFM requirements of a fan.   I'd bet there's a table of HP requirements available for such applications?  Nick?
This is an interesting idea, however, I tend to agree with Tom.  It's more trouble than it's worth to fab up an electric system.  And the custom radiator is going to be made of unobtainium.  Probably manufacturing cost, and not efficiency, is why MCI used the squirrel cage blowers and split radiators for so long.  They never were ideal cooling devices.
And I'll add a  Hypothesis 5:  If you use a bladed fan, sucking is far more efficient than 'blowing' air thru a radiator.   A blade fan in a properly designed shroud is quite efficient.  The shroud makes all the difference.  
Don't MCI D models have the fans on the rear of the radiator?   Seems as though the D model with the radiator centered up in the back would have a natural airflow thru the radiators at highway speeds.  The rear of the upper cap should create a massive low pressure area, and should pull a good bit of air thru the side intakes while driving.  This natural effect would not be available on lower single side mounted radiators.   That's a question...
One other point to keep in mind is that the engine compartment is kept cool by the radiator exhaust flowing over the engine...the lost flow would have to be made up by ducting or another blower of some sort.   
An oversized radiator would also add to the ability to cool with minimal airflow.
As would separating out the transmission, and perhaps engine oil cooling.  The engine oil cooler should be shunted back to the engine coolant in cold weather.  
An electric motor large enough to spin a radiator fan may not be more than a couple HP.  
Our MCIs have 275-300 amps at 24V, so there is a good bit of headroom..much more if the OTR AC is not used.  
Anyone with the fab skills to convert to an electric cooling system could easily repower with a 4 stroke to make the conversion complete.   There are all sorts of 4 stroke donors on the market now.   Cummins and Cats.  Cummins is a better choice.  Complete running tractors for $2K isn't unusual.   They may need a little freshening up, but..that's doable.  A Cummins will offer the best fuel mileage.
Even an occasional S60 is available in a wreck..but they are complicated to install in MC7-9s. 

JR

 
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JR Lynch , Charlotte, NC
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TomC
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« Reply #38 on: March 08, 2008, 09:11:05 PM »

I've seen a picture of the new MCI's-they have huge radiators with huge multi blade (12 blade I think) fans that are belt driven.  One for the air to air and the other for the radiator-both with individual hub clutches.

It's sort of a curious thing that people think that using an electric motor is going to save them fuel.  If you have a 10hp draw fan that has a thermostatically powered switch so that it only runs when necessary, the belt driven will be the most efficient, an electric next and hydraulic the least efficient.  No matter what, if you have a 10hp fan, you're going to use the same amount of fuel whether the power comes off a belt drive, through the alternator and batteries or through a hydraulic pump (actually a bit more with hydraulic).  Personally-big trucks all have direct belt drive fans with thermostatically controlled clutch hub.  What could be more efficient?  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
RJ
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« Reply #39 on: March 08, 2008, 10:55:39 PM »

Interesting discussion.

I was poking around in my 4106's engine compartment today, after reading this and the BNO thread last night, and got to looking and thinking about how GMC handled this "lost HP vs cooling" issue.

Now remember, on a GMC, there are NO belts of any kind - everything is directly driven off the powerplant, in some way.

In the case of my '06, GM used a torus drive for the cooling fan - conceptually a hydraulic version of Gary/Boogie's Horton edy-current electric fan clutch.  When cool, the fan just sort of idles along, almost free-wheeling.  However, as the temps rise, more oil is fed into the torus, until it literally becomes locked up like a torque converter and you've got direct drive.  Pretty simple and effective - and only draws additional HP from the engine when it's needed.

I know that back when I was working in the charter business, I NEVER had a GMC overheat on me, even on the infamous Baker Grade on I-15 or climbing the Grapevine on I-5.  Of course, these were stock, 275 hp motors (N60s/std timing), not the high-HP engines stuffed in many a coach's tail nowadays.  NEVER had an MCI overheat on me either - but you had to watch the temp gauge a LOT more closely than with the GMs.  Of course, that's part of the secret - driving technique.  Maybe the biggest part. . .

Oh, one other point:  GM also included a full-width mud-flap across the rear of the coach directly behind the rear axle.  It's purpose was two-fold:  Act as a mud-flap, and create a low-pressure area underneath the powertrain, to help exhaust the hot air being blown in by the cooling fan while at speed - basically anything over 40 mph.  Amazing to me how many are missing, or a second one has been added hanging from the back bumper to keep stuff off the toad, but defeating the purpose of the factory flap.

I'm sort of like TomC on this - for the average busnut with a STOCK DD two-stroke powertrain, it's awfully hard to second-guess the factory!

FWIW & HTH. . .

 Wink
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RJ Long
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TomC
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« Reply #40 on: March 09, 2008, 11:07:17 AM »

Often wondered why on the bus V blocks they convert the engine to a single out for the engine water return.  On my first truck with the 8V-92TA, it had an outlet from each head with a thermostat, so it had two hoses going into the radiator.  Just a comment.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #41 on: March 09, 2008, 09:15:19 PM »

Tom, I think that the answer is that buses took less horsepower to push, which meant a lower fueling rate and less heat to reject. I can't see any reason that it should be any more complicated than that.

School buses cool just fine while in their original use, but when they go on the highway, they have problems with overheating. I've seen this in a bus with very comparable engine horsepower to a highway rig.

I just see the problem as an average fuel rate, more than anything else.

Tom Caffrey
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Tom Caffrey PD4106-2576
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