Electric cooling fans for bus engine

[luvrbus]

Last I heard 2 Dogs changed his screen name to Tres Perros he really wasn't dumb when it came to buses IMO

[digesterman]

Anytime you change power you lose efficiency i.e. from mechanical to a electric generator/ alternator to a electric fan, or from mechanical to a hydraulic pump to a hydraulic motor to turn fan. Keeping it mechanical (directly hooked to engine) is the most efficient and that's what is desired when needing the upmost from any power source.

Sometimes you have to use different power because the end need for the power consumption isn't at the engine.  I am trusting that the coach manufactures knows best due to the large number of units they have built over the years. If it isn't broke why fix it?    

[uncle ned]

Clifford

I also miss Two Dogs.  He had a different sencs of humor.  also was good at telling a story.  Hate that he got mad and left.

Every one needs to know that a lot that goes on here is bull crap and pay people like me no attention.

uncle ned

[luvrbus]

Yea Ned I miss Boxcarokie,Jim(rv safety),Dallas a lot of old timers that are no longer here 

[shelled]

Electric fans and other systems such as A/C and power steering work well in limited duty cycle applications because they allow a relatively small generator to store energy in a battery over time for use in bursts.  As TomC pointed out, that is not the case with engine cooling.

If you want to increase engine cooling, look at adding external air scoops.  There is a thread here or you can find how it has been done on MCIs at coachconversioncentral.com

e3

[lostagain]

Air scoops, in my experience, don't work. I have observed no difference with them on or off. Other than they look ugly when on, like a worn out old church bus.


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[kyle4501]

I used a flex-a-lite fan that was rated for 300+ hp on a car. After trying to make it work, including adding a huge radiator & ensuring no air could bypass the radiator. I determined the rating had more to do with selling fans and less to do with actual air moved.

If the CFM rating doesn't have a pressure drop listed - then it means absolutely nothing. What you really need is the fan's performance curve, then you can see what it will really do.

If the factory mechanical driven fan used 40 hp, then that is what it takes to cool the beast in the real world.
Only way to reduce the hp required is to get a more efficient fan &/ or a bigger radiator.

[Greg Roberts]

Well what happened to those guys? Yes, that twodogs was a character. Does fast fred still come around?

Yea Ned I miss Boxcarokie,Jim(rv safety),Dallas a lot of old timers that are no longer here 

[Jim Eh.]

http://www.newflyer.com/index/cms-filesystem-action/parts/products/featured%20products/mini-hybrid%20bulletin%20final.pdf

Have a look...

[luvrbus]

A 450 amp 24v alternator to run that setup I don't think so  

[uncle ned]

Yes I miss a lot of the old guys with a different view on things.  Made us think if not more.

I still keep in touch with the three devils that I woke up to after they fixed my Heart. Cody Dallas and BK.  great friends.

Fast Fred posts a few things on the other bus board.

Would love to hear about the series 50 transplant he did.

uncle ned

[bevans6]

For those who, like me, are curious...

http://www.emp-corp.com/products/advanced/FI-11-electric-fan/

The literature says variable speed, up to 25 amps, and 1400 cfm.  8 would be 200 amps and 11,200 cfm, but only drawing 0.4 Kw at that rate, which is only 16.6 amps so maybe the 25 amps is for when it runs at 12V nominal (it is rated for 9 to 32 V).  There are other versions up to 12 fans, and you would have to see what heat rejection the radiator is spec'd for, but I think the application for a two stroke would be harder than for a four stroke.  You would need to optimize the radiator to get the cooling with the low air rate.  The alternator spec'd at 450 amps is designed to be running at no more than 50% output for cool running and long life, it's an air cooled alternator (they list an oil port block-off kit presumably for 50DN conversions).

The issue with just putting electric fans on a two stroke usually boils down to radiator efficiency more than fan capacity.  The stock radiator is designed to have a very large airflow developed by a high horsepower mechanical fan.  It's too small to have the high efficiency that lets it develop the cooling capacity with smaller airflow from electric fans.  That means a conversion from mechanical to electric means a replacement for both the fans and the radiator, which oddly is exactly what this retro-fit kit is...  Look at this picture and you get a sense of the size of the system to cool what is probably a relatively low power four stroke.  I've seen buses with that setup running around Toronto, I think.

Brian

[luvrbus]

I bet a coke Brian with the demands of the HVAC systems in the bus the 450 amp alternator runs around 85 % that sure looks like a expensive and high maintenance system,most of the transit engines are 4 stroke CNG engines wonder how much heat rejection they require it has to be small compered to a 2 stroke

[TomC]

I don't understand why anyone would change what has worked for many, many years-like the mechanical radiator fan drive. I have an 8 blade 32" direct drive fan on my bus. I realize it uses lots of power, but 2 strokes are hard to cool-especially with the addition of the air to air intercooler.

On our new Freightliner trucks, we still use belt driven fans with on/off thermostatically controlled clutches. Fuel mileage is getting to be such an issue, Detroit Diesel just made two modifications to the DD15 engine. First, they eliminated the turbo compounder. This is a second turbo right after the normal turbocharger. But instead of pushing more air, it is engaged to the engine through gears on the back of the engine. On a hill climb, it can add up to 50hp for free back into the engine. That works great. But what the engineers discovered, is on any other type of driving that involved less then full power, the turbo compounder actually pulled power from the engine to keep spinning. Hence by eliminating it, the overall mileage average went up. And second, the engineers have modified the water pump to be a clutched thermostatically controlled unit. They discovered that the water pump draws about 5hp all the time. When the engine is not working hard, the water pump disengages and just turns over slowly. At least they had the fore site to make the clutch fail in the engaged position.
With all these fuel saving engineering tricks going on, don't you think the first place the engineers would have looked would have been replacing the mechanical clutch fan with electric? Obviously, even on a front engine with ram effect from forward motion, the engineers feel that electric just isn't enough. Good Luck, TomC

[TomC]

On my both of my trucks, I had a 1350sq/in copper/brass radiator. With the 2007 engines using 25% exhaust gas recirculation, the raidators went up to 1650sq/in. Now with the 2010 engines reducing the EGR to 10%, we can get away with 1400sq/in radiators up to 505hp and 1650lb/ft torque. When the DD16 is ordered, the 1750sq/in radiator is used.

What's interesting is that the normal Diesel ISL 8.9 liter Cummins uses a 1200sq/in radiator. Order the ISLG natural gas version, and even though the horsepower drops from 380hp and 1250lb/ft torque on the Diesel to 320hp and 1000lb/ft torque, the natural gas engine has a bigger 1300sq/in radiator. Shows how much more natural gas heat rejection is. I don't like natural gas. There are many exhaust emissions that natural gas isn't even regulated-like fluorine, carbon monoxide (you'll never see an inside fork lift powered by natural gas-you will see propane powered indoors), raw gas emissions from over pressured tanks, etc. Stick with good old Diesel which is just a fraction away from being as clean running as natural gas. Good Luck, TomC