Electric Fan Conversion

[rednec]

I decided to do an electric fan conversion on my truck this weekend. All went well and seems to be cooling just as good as the stock clutch fan did. I will find out tomorrow if everything will stay cool. After getting everything hooked up I went for a drive with the A/C on and then parked with the engine running for approx. 15 minutes and the temp. gauge stayed just below the midway point. Total cost was right at $100 for a 16" fan and an electric t-stat. I had also bought a 10" fan for a dual fan set up but forgot that I would have to drop the front bumper in order to pull the grill to install the fan. If the single fan set up works out then I'll take the other fan back. The t-stat I bought is set up for dual fans. It took close to 3 hours, a couple beers, a pack of smokes, some scratched up knuckles and a few choice words to install everything. Guess I have a few more items to add to the pile of parts removed from the X. Thanks to Kennedy??? for the idea to do this. I believe he was the first to do the conversion. I'll try to take some pics this week and post them.

[ChuckH]

Hmmmm, I've been thinking of the electric fan conversion too. I'm looking forward to seeing your pictures and such. Keep us posted!

[Harbones]

Just out of curiousity (or rather, my igornance), what fan did you convert and what does the conversion do for you?

-Harbones

[warmonger]

I am most interestested in how it performs under duress. In other words, how does it do when off-roading? Especeially in low range where the rpms are up but the truck isn't moving very fast. I know during engine phase I will be putting a tranny cooler with fan on the front of the truck, but I was debating whether I should put an electric fan on in place of the engine driven fan. Let me know what you find.

[Lance]

Harbones -

OK - He is talking about the radiator fan....it pulls fresh air through the radiator to cool the engine...

A mechanical fan turns when the engine turns (A drive belt...)...so the faster the engine is running, the faster the fan blades spin, and the more air is pulled through...in addition to the air moving through the radiator from the truck going foward through the air...

When the truck is idling...and the engine rpm is slow, the fan isn't pulling much air....and it might overheat.

An electric fan pulls at the same speed, no matter what the engine is doing...so it pulls more air at slow/idle speeds...keeping the engine cooler.

An electric fan can also be dash switched, so you can turn it off on water crossings to avoid underhood splashing, etc.

Some people mount a (Pusher) electric fan on the opposite side of the mechanical (Puller) fan...so they get the benefits of both.

An electric fan w/o the mechanical fan can save gas/power too...because the drive belt power is not being drained by the mech fan anymore...

If the Elec. fan set up is sized/geared/bladed properly...there is no trade off...Cooling-wise - its all good. ...There is of course (some) extra load on the battery/alternator....a factor to worry about if you are stock alternator equipped/overloaded with offroad lights, winches, onboard coolers, airtools, etc.....

The problems, if they are to occur, are typically due to the fan blade design...pitch or variable pitch, swept area vs shroud overlap, etc....assuming the unit is designed for your application at all...They typically size them based upon horsepower of the intended engine to be cooled, and a diameter it has to fit within.

They cannot account for all of the rig specific variables, such as obstructions to airflow on the engine side of the flow preventing/hindering cross ventilation...or to the exterior, such as a winch blocking/hindering the intake air....so there is some trial and error involved.

The hardest trial is typically a hillclimb, or pulling a heavy load, etc...where you are working hard, under load, which makes the most heat, and going slowly, which limits the rig speed related airflow as well. (A condition where you have - The most heat to dissipate, combined with the least air to carry away the heat)

Does this help make sense of the discussions above at all?

[rednec]

I let my truck run for about 20 minutes at idle with the A/C on this morning and the temp. gauge started getting real close to the read. I will more than likely be adding the second pusher fan this week to help compensate. Overall the single fan setup has worked well. I tend to overdue things sometimes just to be on the safe side. I have noticed a little more pick up on acceleration with the mechanical fan off. A clutch driven fan, like the X has, tends to rob alot of engine power.

[Harbones]

Originally posted by Lance


Does this help make sense of the discussions above at all?

Wow Lance, i dont think i could have asked for a better, more detailed answer. Thanks :frog:!

[ned946]

Not to be a prick, but I though I'd throw this in since it is the topic of a couple of off-road mags this month. They found that NOTHING made a difference except changing from coolant/antifreeze to straight water (no, they did not recommend doing this due to the obvious problems associated with straight water)!!!!!

They changed from mechanical to electric, tried different types of mechanical fans different types of coolants.

They did NOT try adding an accessory engine oil cooler (which I think would have helped greatly)

See Petersen's 4Wheel October 2001 (it has "ULTIMATE ADVENTURE" on the cover).

[Lance]

Without reading the article...I can say there must have been one of the limiting factors I mentioned (Or skipped/didn't think of...) going on. I have way too much evidence to the contrary.

My off hand guess is that IF NONE of the mods worked ...it was most likely that the airflow was blocked, either on the way in (Less likely, or they would have noticed/corrected for it first...), or on the way out of the engine compartment....that's about the most likely thing to negate ALL of the mods except plain water...because that's the only one that should work by itself independantly of airflow, at least somewhat.

If the airflow is hitting the radiator like a wall, because there is no where for it to go on the other side, then THAT's the only thing you might have to fix. Once you have a clear path for the flow through the radiator...then the other mods can work. (Same applies if they had a winch in front, or a plow, etc...for those...an air dam/sploiler to force air around the obstruction and into the radiator face can help)

Adding radiator fans that are working against dead air space will prove futile.

To get the air out of the engine compartment...take out/vent the sidewalls of the inner fenders and or vent/louver the hood, trim the bottom of the bulkhead/firewall and or mount a puller fan to the back of that engine pointing down, and or up through the hood, whatever path(s) you make to get flow out of the engine compartment. (Vents/louvers alone are usually all you'd need)

....There are alot of variables to eliminate....but it sounds like a blocked air flow problem so far (My best guess)


Otherwise, its like having a car with no spark plugs, boring it over, adding fuel injection, a super charger, lower gears, Nitrous Injection, etc...and then reporting that NONE of them improved the zero to sixty times....


So - Make an idiot of me...did they say what they did to finally cool it down? (Something I didn't think of I'm sure...)

[ned946]

Well, I'm not much a Jeep expert, but I think they had a "Flat Fender" Jeep with a huge motor in it. They probably had the most difficult task one could think of in terms of cooling. A small radiator with a "plugged" airspace as you mention. I just tought the timing of the article and your post was perfect. ....I don't know if that article is applicable to what your doing or not, just thought I'd mention it and what their findings were.

Okay, I went back and looked at the article. They origianally had an electric fan and though a mechanical fan would be better. They, in essence, reconfirm you observations. The electric cools better at low speed. The article may still be of use if people are considering changing fan blade types, water pump......that stuff will have no effect.

[Lance]

You can't say NO effect....every cooling problem has a cause...each cause has its own cures.

If your water pump is cavitating or undersized, etc...replacing it is the cure...if your thermostat is stuck/shot/wrong temperature range...replacing it is the cure...

The main concept for you to think about is what the limiting factor is. That's the one thing to change...and that may be the ONLY change worth making...even if it would have no effect on another rig.

[ned946]

Again, don't want to flame
So, please don't shoot the messanger! That was their words....but they did acknowledge what you had said earlier...that there was an underlying issue of airflow through the compartment.

You have not commented on what I am considering, which is an accessory engine oil cooler. It seems like a simple install and benefits at all speed ranges?!?!?

http://www.derale.com/derale/index.html

See fan mounted oil coolers.

[Lance]

I didn't think you were flaming...just that you had read an article that had discussed trying to fix and airflow prob by doing every thing except the airflow prob...where they concluded that none of the mods worked...like tests saying a turbo charger won't make you go faster, but you still have no gas, with or w/o the turbo...etc. (Misleading conclusions)

Oil coolers are good if your oil is too hot. Transmission coolers are good if that oil is too hot, etc...

If the stuff isn't too hot, you won't get much bang for your buck, even if it's just one buck.

Radiators that have the tranny cooler, etc...inside them....can get real gobs of heat from even the tranny fluid, auto trannies oils are at 300ºF or so...that's a lot of heat to dissipate...if you run hot while climbing/under load...tahn that might be a worth while addition...a free standing cooler for the fluid of choice....if you don't run hot, you won't see a difference (You might FEEL more secure).

So - These things can help individual probs...but they add up, so you do what you need to....just know what you need to do first...it sounds like they just randomly tried out aftermarket accessories or something...especially as you say they think they might have had an underhood airflow problem....on a Flattie with a big V8....

(That's like Ikea saying "Some items might require assembly...")

I hope the take out the fender liners/louver the hood or something before they melt it down.



Cooling is always the heat dissipation...either the coolant can't carry the load (Inadequate volume/wrong coolant, etc.), the air can't carry the load (Flow prob, etc.), or there's no transport of the load from one to the other (Fan or radiator surface area deficiencies/mineral deposits/stuck thermostat, etc.). (Examples)

So An Asbestos Free Topic....

[ned946]

I wanted to explore the engine oil cooler a bit more. Now, the engine oil is lubricating the engine and (as I understand it) in more intimate contact with the heat producing portions of the engine than is the coolant. The coolant is run through cavities within the engine. What I'm getting at is, no matter how you remove the heat, it will benefit the engine in low speed, high demand situations. I would assume that if you remove heat by an oil cooler, you reduce the demand of the radiator overall. I think I may be off topic a bit, cuz I think your original point was to increase HP by reducing the drag of a mechanical fan with an electrical fan. I am concerned with increased demands by running (in the future) 33's, excess weight and increasingly demanding (steep) trails.
I do think you will get power benefits from your approach.

So, as you say, it really depends on what your after!

[Lance]

Atz ryt!

You can take Penicillin if you are not sick, and it probably won't do any harm....but if you have a Fungal infection, it won't do any good either.

If the engine runs in the proper heat range...you can actually sabotage it by forcing it to run too cool. The spark plugs, etc...are calibrated for a heat range...things like carbon deposits in the engine, excess HC emissions, etc...can all result from making an engine with too much cooling capacity (Like one that can never "warm up"...it can't reach operating temp)

If it ain't broke, don't fix it until it is.