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Old 07-30-2016, 02:00 AM   #11
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You will need about 2500w of electric cooling fan to match the mechanical fan's air flow. For a 300 odd HP engine.
The relatively slow engine speed gives more heat transfer than a Gasser.

There's a Volvo research paper on the web, where they go through it fairly thoroughly. The added bonus is you lose less power going electric over mechanical. About 5hp on the alternator but 30-50hp less off the crankshaft.
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Old 07-30-2016, 09:50 AM   #12
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i added a couple electric fans to my bus. extra cooling for traffic or hills.

i dont think i'd swap an electric fan for the hydraulic one, i wired the fans to a switch and a tstat. hoping they function to keep me out of the hyrdraulic fan temperatures.
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Old 07-30-2016, 06:04 PM   #13
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i added a couple electric fans to my bus. extra cooling for traffic or hills.

i dont think i'd swap an electric fan for the hydraulic one, i wired the fans to a switch and a tstat. hoping they function to keep me out of the hyrdraulic fan temperatures.
Our issue is the hydraulic went out and we can't find the parts to fix it...so thinking of converting the whole thing to electric cuz we need it for our up coming tour.
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Old 07-30-2016, 06:04 PM   #14
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You will need about 2500w of electric cooling fan to match the mechanical fan's air flow. For a 300 odd HP engine.
The relatively slow engine speed gives more heat transfer than a Gasser.

There's a Volvo research paper on the web, where they go through it fairly thoroughly. The added bonus is you lose less power going electric over mechanical. About 5hp on the alternator but 30-50hp less off the crankshaft.
Awesome thanks for that info!
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Old 07-30-2016, 06:08 PM   #15
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I am installing electric fans on my 4BT. The mechanical fan unit is heavy and pulls around 10 HP that I can use for other things. And given that I have to stack so much in the nose of my rig (rad, tranny cooler, CAC, A/C) ...it will that task much simpler.
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Old 08-01-2016, 06:55 AM   #16
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If you get really keen on electric fans visit an excavator /off road plant yard. There's some interesting setups, on the fly reversing flow to dump the crud out of the radiator and things like that. Probably have a similar solution as a bolt in fit.
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Old 08-01-2016, 09:34 AM   #17
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talk to borg warner directly.. they likely make a clutch or air clutch that will fit your bus.. and yes they will talk to individuals.. I called them when I replaced my viscous fan clutch to see how to adjust its temperature down a bit..

they have a retrofit air-fan clutch to replace a viscous factory clutch... they also have about anything,,

also kit-masters is a company that specializes in selling fan clutches to fit anything.. they have a "builder" on their site.. you measure your fan, directions, type of drive, etc and plug in the numbers to get an idea of some part numbers then you cvall them and they will help you...

I did some CFM calculations on my bus that has a 6 blade metal fan and even in the partial engage mode where my fan spins at roughly 380 RPM constantly that the CFM there is nearly what a lincoln Mark VIII fan puts out.. ive used the MARK VIII fans to cool hotrods and their A/C units for years but I dont think they would stand a chance cooling a bus thats pulling a hill or being driven flat out...

the myth that you need virtually no fan on the highway is just that a myth.. esp in the hills..

I just drove my bus on a 1400 mile road trip in changing weather... through flat ground and small mountains up to 3200 feet.. when the temperature was above 75 my fan went to full engage at least some point on ANY hill... and on the steep ones would run that way for a couple minutes at a time... at full engage my fan is likely pulling 15,000 - 20,000 CFM... a Mark VIII fan maxxes at 5000 RPM with no static pressure...

in 95 degree heat my fan was going full engage even on flat ground.. and I was pretty easy on the bus.. i ran the trip at 60 MPH the whole time.. my foot was only on the floor when I was in the hills.. otherwise I was not pushing it...

-Christopher
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Old 08-02-2016, 04:52 AM   #18
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Cleanfix.org is another similar solution just electric drive.

7* spal 12inch fans in a custom shroud is another, requires a custom controller and 2500w of electricity.

There's certainly plenty of options around if you look.

Would be an interesting mod having the ability to spit the crud from your radiator all over that car that just jumped into your braking area stopping at the lights.

Reading somewhere the fan on mine should be fully engaged at 1200rpm and 25c ambient. So yes +1 on what Christopher said about fan being engaged at highway speed.
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Old 08-02-2016, 08:47 AM   #19
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I find it odd, but according to the diesel gurus over at 4BTSwaps...Cummins engines run on the cool side compared to gas or most other motors. Many of them have made the conversion to electric fans and comment that even in hot weather they rarely switch on at all unless pulling a load up a hill.

That said, I do plan on trying to over build my cooling system and include a couple of temp sensors plus a manual on/off switch. The trans cooler will be completely separate and electric as well.
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Old 08-02-2016, 09:09 AM   #20
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I find it odd, but according to the diesel gurus over at 4BTSwaps...Cummins engines run on the cool side compared to gas or most other motors. Many of them have made the conversion to electric fans and comment that even in hot weather they rarely switch on at all unless pulling a load up a hill.

That said, I do plan on trying to over build my cooling system and include a couple of temp sensors plus a manual on/off switch. The trans cooler will be completely separate and electric as well.
you are also running a smaller engine and a smaller bus too... your radiator size ratio to engine size will be high compared to an RE bus or esp the 'DT' conventional busses.. the 'DT' conventionals have half the grill area as the turbo cooler and half as the radiator as opposed to a stacked position like most turbo-charged vehicles.. the result is very low radiator area / engine size ratio so they rely on the fan to do a lot of the cooling esp in hard pull situations... at idle or around town my fan clutch's low-speed constant is pretty much enough to always cool the bus unless im doing a ton of stop / heavy accelerate, stop, etc.. like stop and go traffic where the traffic goes from 0 - 35 - 0 - 35 etc..

electric fans will easily cool a very ;arge bus when the speeds are constant at a low level.. or I should say engine loads not speeds...

but pull a mountain pass where your foot is to the floor and the engine is under full load slowed below governor RPM... thats where you make heat... lots of it.. if you have a Huge coolant volume that can absorb that heat then you would be fine as your fans can remain on high speed aftyer the engine loading has ceased.. the cooling system will dissipate more heat than is being produced until the temperature is back to normal.. but if your cooling system isnt large enough to absorb that load, it relies on the ability to dissipate all of the heat produced as it is produced..

I dont know what the engineers used for numbers and capacities when designing the RE busses from the factory... or the conventionals.. but I do know from having a bad fan clutch that always stayed at a constant 300 RPM on my DT360 conventional is that it stayed at 195 or below most of the time until I got it on the highway or in stop-go traffic then it warmed up.. It needed more cooling than it was achieving some of the time..

Tango's bus is custom and so the cooling system for it must be designed according to the custom design.. and I venture to say the radiator cvolume will be somewhat small just because of size restraints.. and then rely on fans to dissipate the heat as needed...

its my belief that cummins engines tend to run cooler because their torque curve is pretty extreme at lower RPM's allowing the engines to "unbury" themselves pretty easily from being Lugged.. Lugging any engine will make tons of heat... alas why gasoline engines detonate or "ping" at Lugged low RPM's.. the cylinder head temperature are quite high during that timeframe..

Im all about electric fans in general... ive used them in most every hotrod i ever built with great success.. but I also had nice big aluminum radiators where I had high radiator volume ratio compared to engine size..

-Christopher
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