Electric cooling fans

gmctd · **Posted:** Mon Mar 31, 2008 10:25 pm

That's because the 6.5TD was a Cummins\Powerstroke catchup tack-on upgrade to the 6.2L in '92, the 6.2L specifically designed to be a 135hp Diesel engine in 1982 when Congress gave the ultimatum to GM: get the 1500\2500\3500 series pickup CAFE up outta the middle single digits, or lose the 350 and 454 engines - the 135hp 6.2 gave over 30mpg on that first edition, with '82-'86 descendents still on the road today, returning 25-30mpg in the 1500 swb version - the constant overheating in the 6.5 series was due to the indirect injection design of the heads - water circulation around the precup\valves area was sufficient for 135hp, but not for the increased btu at 195hp - nor could it be improved, as that head is still in use today on the Hummer, with only minor variations in the water jacket - thus the various concatenations of dual t-stats, ho waterpumps, multi-bladed fans, various wp\fan drive ratios - there is a fix, but it's external, and relatively expensive - we've been field-testing one on a friend's truck, and the DOD has approved it for military use.

So, you wanna talk Diesel engine cooling, you've come to the right person - gasser cooling is irrelevant in a Diesel conversation - and I did fudge a little on the airflow, for the sake of the conversation - actual airflow is over 10000cfm at 3000rpm, behind the radiator, not free air.

Electric fans are good for idling and coasting in Neutral - put a load on the engine, and you can kiss it goodbye - they are functional as auxiliary augmentation, if desired, but not as primary cooling

Goglio704 · **Posted:** Mon Mar 31, 2008 10:30 pm

9000 CFM is not a huge number. A large roll around fan is rated at 9000 CFM and runs off a 1/2 HP electric motor and a squirty little belt. 8 or 9 amps at 120 volt. Figure 80 or 90 amps at 12 volts - which is why automotive electric fans don't come that big.

tjkj2002 · **Posted:** Mon Mar 31, 2008 10:52 pm

[quote]That's because the 6.5TD was a Cummins\Powerstroke catchup tack-on upgrade to the 6.2L in '92, the 6.2L specifically designed to be a 135hp Diesel engine in 1982 when Congress gave the ultimatum to GM: get the 1500\2500\3500 series pickup CAFE up outta the middle single digits, or lose the 350 and 454 engines - the 135hp 6.2 gave over 30mpg on that first edition, with '82-'86 descendents still on the road today, returning 25-30mpg in the 1500 swb version - the constant overheating in the 6.5 series was due to the indirect injection design of the heads - water circulation around the precup\valves area was sufficient for 135hp, but not for the increased btu at 195hp - nor could it be improved, as that head is still in use today on the Hummer, with only minor variations in the water jacket - thus the various concatenations of dual t-stats, ho waterpumps, multi-bladed fans, various wp\fan drive ratios - there is a fix, but it's external, and relatively expensive - we've been field-testing one on a friend's truck, and the DOD has approved it for military use.

So, you wanna talk Diesel engine cooling, you've come to the right person - gasser cooling [b]is[/b] irrelevant in a Diesel conversation - and I did fudge a little on the airflow, for the sake of the conversation - actual airflow is over 10000cfm at 3000rpm, behind the radiator, not free air.

Electric fans are good for idling and coasting in Neutral - put a load on the engine, and you can kiss it goodbye - they are functional as auxiliary augmentation, if desired, but not as primary cooling[/quote]

Some good points but the cooling system on a deisel(just like the gas engines) is not the primary cooling system,the engine oil is.The cooling system is mostly to stabilize the engine temps.I've worked on plenty of deisel in 9 years and know how they work and all the sub systems,the cooling systems are identical from a gasser to a deisel,same purpose.90% of deisels used in the US are used to tow so yes a mechanical driven fan is better due to heavy loads and low speed manuvars.Just electric cooling fans have been cooling vehicles for 20 years now with no problems.

I worked on a deisel powered rig that weighed 55,000lbs,8 wheel drive,8V92TA Detriot in it,and no mechanical fan.It ran a hydrauilic fan with the radator mounted above the engine with the fan,never overheated one of those,not even towing 120,000lbs up a 12% grade for 10 miles.The hydrualic fan was just like a electric fan,temp controled and regulated for just one speed.
Engine temps keeped at a messly 165 degrees.
I also worked on many Cummins powered trucks that would overheat often with there mechanically driven fan,it wasn't big enough,guess a 36" fan isn't big enough.

Reflex · **Joined:** Mon Jan 29, 2007 8:48 pm **Posts:** 567

About HP, wouldn't any serious draw on the electrical side of thing still steal HP since after all it forces the alternator to work harder to generate the current? If it didn't, then why would anything electrical affect mpg? Somethings gotta be working harder to produce that power, and due to conversion losses its bound to cost more in whatever terms you choose to decide are important than just going straight mechanical...

The argument I see for electric fans is that if the fan can be switched off most of the time it is possible that it might save a bit of power overall, but when its running its clearly going to take a lot more than your original mechanical fan did.

Personally my biggest concern would be when pulling a load or during the summer in stop and go traffic since it won't push as much air if I'm reading gmctd right....

Turbo Tim · **Posted:** Mon Mar 31, 2008 10:59 pm

That "Free" power to run the electric fans comes at a cost of about 7 HP to run the alt at full power.

tjkj2002 · **Posted:** Mon Mar 31, 2008 11:00 pm

Reflex wrote:

About HP, wouldn't any serious draw on the electrical side of thing still steal HP since after all it forces the alternator to work harder to generate the current? If it didn't, then why would anything electrical affect mpg? Somethings gotta be working harder to produce that power, and due to conversion losses its bound to cost more in whatever terms you choose to decide are important than just going straight mechanical...

The argument I see for electric fans is that if the fan can be switched off most of the time it is possible that it might save a bit of power overall, but when its running its clearly going to take a lot more than your original mechanical fan did.

Personally my biggest concern would be when pulling a load or during the summer in stop and go traffic since it won't push as much air if I'm reading gmctd right....

The newer electric fans draw less amps then the older version and pull more CFM's,they pull less power from the alternator that today is producing more amps anyway so the drain is virtually invisible.

If your towing in a very hot day in stop and go traffic you should be just fine with a CRD and only a electric fan,you may need a mechanical fan if your hauling 15,000lbs in a 1-ton truck.

I've towed near 500lbs for 1500miles and I only have a electric fan,no overheating issues at all.If your CRD overheats with just a electric fan(the correct rated one) then time for a new vehicle since it has major cooling issues that are "masked" with overkill cooling.

tjkj2002 · **Posted:** Mon Mar 31, 2008 11:02 pm

Turbo Tim wrote:

That "Free" power to run the electric fans comes at a cost of about 7 HP to run the alt at full power.

In a deisel or gas? I believe the deisel runs a 90 some amp alt,most electric fans pull like 10-14amps,turn your butt warmers off and you'll see no extra drawdown from the alt.

Oh and it will be taking that 7HP away regardless with all the techno gizmo's in your CRD's,even without the electric fan,so add about 15-20HP on top of that to turn that mecahnical fan.

7HP loss,or 27HP loss? Which one would you choose?

Turbo Tim · **Posted:** Mon Mar 31, 2008 11:21 pm

The rest of y'all don't get to appreciate the Southwest at all. Here in Phoenix, the air temp 3' off the black asphalt is around a nice 145*. Add a nice heavy load and a 4' X 8" radiator isn't big enough.

The "New" style electric fans with their pancake motors (like Stall, etc) still draw over 30 Amps! The spacing, size, and length of the blades cannot and will not produce a usable CFM through a radiator.

To compare walnuts to walnuts, a typical large 7 blade, hydrostatically coupled Non-flex type fan, will produce well over 4000 CFM @ 15 Inches of water column pressure! Your best 16" electric fan will only produce 0.5 inches of water column pressure. Use something like an Alnor Air Velocity meter to check your work.

CFM is meaningless without how much pressure it can push or pull (like through a radiator).

If someone knows of an electric fan that can even come close without drawing over 100 Amps that can do the same job, You will be very rich very quickly. Please PM me.

dieselenthusiast · **Posted:** Tue Apr 01, 2008 12:20 am

Diesel Power Magazine did a write-up on ways to increase fuel economy. They installed a flex-a-lite into a Dodge Cummins, To make a long story short, the truck gained more horsepower, torque, and fuel economy. The technology for these cooling fans have come a long way. “Electric fans also allow quicker warm ups and cool downs, longer water pump life, less fan noise, improved air conditioner performance and improve gas mileage.”
http://www.flex-a-lite.com/auto/index.html

Reflex · **Joined:** Mon Jan 29, 2007 8:48 pm **Posts:** 567

I'm still having difficulty believing that this would result in any serious gains. If it did, why wouldn't the manufacturers use it? I thought someone said the gas version of the KJ already has one, so if it was a good idea for the diesel one, why wouldn't they?

Color me very skeptical.

Sir Sam · **Posted:** Tue Apr 01, 2008 12:50 am

Reflex wrote:

I'm still having difficulty believing that this would result in any serious gains. If it did, why wouldn't the manufacturers use it? I thought someone said the gas version of the KJ already has one, so if it was a good idea for the diesel one, why wouldn't they?

Color me very skeptical.

Because its a tradeoff, yes you might have less parasitic loss, but your more likely to have cooling problems.

The newer WJs had a hydraulically driven fan, as well as an electric fan, the PS pump also powered the fan, and it could be turned on and off with hydraulic pressure.

gmctd · **Posted:** Tue Apr 01, 2008 1:05 am

Correct, Reflex - capacity is the most important point - there is not enuff power in automotive systems to drive an electric fan to the capacity required for full cooling - hydraulic fans are another story, but none are small enuff to fit the KJ: pump, motor, fan, hosing inclusive - and you get additional losses in hydraulic pumping - losses above those already accounted for in the coolant pump.

Comparing large Diesel engine cooling systems to small Diesel engine cooling also doesn't help, because the coolant systems in those are so large, they required shutters over the huge radiators to help maintain correct temperatures, and now have electric-clutched and hydraulic fan drives, and exhaust recirculation, allowing further control -

'Nuther words, because of the large mass and huge volume, they have too much cooling capacity, where we have minimal, due to real estate limitations in the KJ chassis - start pulling a heavy minimal aerodynamic load thru hills\mountains, btu's up, IAT up because Boost is up, meaning air flow thru the charge-air cooler is up even B4 it passes thru the radiator (IAT's at the compressor outlet are usually ~300degF at 15psi), and air cond condenser temps are up because local ambients are hot, so flowing air temps are elevated even B4 they pass thru the hot c-a cooler to the hot radiator, full of engine coolant raised above 220deg by the increased btu generated to meet the job at hand - see if that wimpy 1200cfm free-air electric fan will save yer bacon, then (there's no room for that 'godzilla' 24" 3300 free-air cfm version) - the oem engine-driven fan will do so, as it was designed to handle that greater output, and the full load power drain was accounted for in the design.

Even at that, I think overall cooling capacity is minimal, partly due to space limitations, but based on the KJ's minimal towing capacity - this engine in a Dakota pickup, with it's sturdier frame, wider stance, increased braking, and room for increased cooling, would handle way more than DCJ's spec'ed 5000lb KJ limitation

I agree - keep engine oil temps cool, partially heated from the oil sprayed on the pistons to remove combustion heat, allowing increased EGT's, and the engine runs cooler, overall - again, because of the large cooling capacity of the 18-wheelers, engine coolant can be controlled to completely stabilize temperatures throughout the water jacket, reducing hot spots, passing the combined therms from oil cooing and water jacket cooling to the atmosphere as necessary - similar in the KJ, but we have minimal cooling capacity, due to the constraints of the small chassis - we'd be a lot better off with a 4'wide by 6'tall radiator, but they just couldn't squeeze one in there, for some reason - prolly same reason we didn't get many cupholders...........

So, if granny only drives her KJ CRD up to CVS pharmacy for a quart or three of Hadacol, then an electric fan could possibly replace the engine-driven fan - if she's a flatlander, and wants to scoot across state to visit the grandchildren, again, prolly ok - but if she intends to pull her 20' rv trailer over the hills and thru the woods, it would be another story, indeed - the load: weight, hills, aerodynamics, is the killer, as she would have not experienced the temperature extremes during the trips to CVS, and would have no inkling of what was in store under those new conditions.

Coolant capacity, and cooling capacity - or rather, insufficient capacity due to substitution\modification, is the point - and we're talking an engine which is steadily being modified and uprated from oem factory design specs - so, only input specific to this engine in this chassis is valid - Cat engines - Cummins engines - Detroit Diesel 8.2's or 6.5's or 6.2's = irrelevant, even if someone has installed one in this KJ chassis - if you've modified the VM 2.8L CRD TD coolant system, that is pertinent to this thread - all other input is trivia, and confuses the issue: will an electric fan(s) adequately cool the VM 2.8L CRD TD engine in this KJ chassis, and will removing the engine-driven fan result in greater fuel economy with this engine in this chassis.

My answer is no, and no, based on the information I've posted relevant to this engine in this chassis, also considering the accomplished and proposed power upgrades to this engine in this chassis - my other input is just response to stimulae, and irrelevant to the subject matter

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Reflex wrote:

I'm still having difficulty believing that this would result in any serious gains. If it did, why wouldn't the manufacturers use it? I thought someone said the gas version of the KJ already has one, so if it was a good idea for the diesel one, why wouldn't they?

Color me very skeptical.

More telling is that the mechanical fan system on the CRD comes as an upgrade on the gassers (I believe with the towing package, correct me if wrong), I know three people who's CRD's have overheated in AZ. Two while going down the road at highway speed, the third while off-road. One of the highway issues was a broken/defective mechanical clutch. The other had trimmed his bumper. The air dam on the bottom of the bumper sucks air up into the engine bay. Cutting it gives you more clearance, but it appears to decrease airflow in the engine compartment. The off-road instance occurred on Crown King when it was 113 out. He turned the AC off and took it easy and the temps dropped. He was running with no ORM-- the EGR working.

So the stock system can be taxed enough down here to get it to overheat. You have the ac, the transmission cooler, the radiator, and the inner-cooler all sandwiched together. When it its hot out they are going to keep dumping more heat into each other and the fan has to pull that through all of them or they heat soak. I would not want to replace the stock fan with anything that was not at least as good.

The hood louvers are looking like the way to go in AZ. BTW, you can easily remove the rear heat stripping off by the windshield (at least I could). It was not put on with adhesive and can be snapped right back on. I am going to try removing for a bit this summer (and the hood insulation) and see what it does to the temps under the hood using the infared temp laser thermometer (if the heat does not dump into the ac intake too bad).

gmctd · **Posted:** Tue Apr 01, 2008 1:22 pm

FYI - one member here had added the KJ V6 elect fan, front of the ac condenser, for augmented cooling - should be no problem if others follow suit - just don't even remove the engine-driven fan, if you like your KJ CRD

fastRob · **Posted:** Tue Apr 01, 2008 5:30 pm

My CRD has both types, electric and mechanical. They appear stock.
I checked the VIN Summary Report and there was listed, Tow Group and preferred packages 2TC and 22C on the options list.
Funny, here in Maine's freezing cold I have both, seems unnecessary.

R

crd liberty · **Posted:** Tue Apr 01, 2008 5:35 pm

fastRob wrote:

My CRD has both types, electric and mechanical. They appear stock.
I checked the VIN Summary Report and there was listed, Tow Group and preferred packages 2TC and 22C on the options list.
Funny, here in Maine's freezing cold I have both, seems unnecessary.

R

I have the tow package on my 06 and have both fans as well.

gmctd · **Posted:** Tue Apr 01, 2008 6:41 pm

That's good news, but does seem to indicate the cooling capacity is fairly well taxed, already - even more reason to not remove the engine-driven fan

fastRob · **Posted:** Tue Apr 01, 2008 8:15 pm

gmctd wrote:

That's good news, but does seem to indicate the cooling capacity is fairly well taxed, already - even more reason to not remove the engine-driven fan

THe e- fan acts as a block with the shroud when not running so in the winter that would be warmer.
Are both better in the summer? Seems like overkill to me. Would not the mechanical fan alone be best.
Would rather have a screen,blanket or louveres in the winter, free flow in the summer. Opinions please.

R

gmctd · **Posted:** Tue Apr 01, 2008 8:17 pm

Best advice would be to wait till summer, see whatcha got, then report back - particularly if you start towing thru hilly\moutainous terrain - the same Diesel engine you can put your hand on at 160deg when tooling around town will roast chestnuts at 240deg under continuous load

DarbyWalters · **Posted:** Tue Apr 01, 2008 8:49 pm

Everyday use...stop n' traffic...AC running...pulling air thru for condensor/radiator/intercooler...just doesn't make sense to remove the mechanical setup.

You want better dyno numbers/drag strip time slips/0-60 times...sure you can increase numbers...or decrease times. Will it do you any good for everyday Jeep Liberty CRD driving? These are little mules stuffed into a small engine bay...they need relief! The SEGR helps quite a bit to lower thermo stress.

As for comparing to a gasser? Different animal here. Not diametrically different but different enough.

Electric cooling fans

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