Electric vs Mechanical fan cfm

Brianawd · **Joined:** Wed Apr 03, 2013 12:59 pm **Posts:** 130

I live in Portland where the temps stay around 80deg most the summer.
Even this summer the front fan never kicked on once. I had my volt meter
On it for about a week this summer so I could judge how much it's used.
I think the one big electric fan should me more then enough.

Thanks for the info. I will make sure when I get it all done I watch it

Auberon · **Posted:** Fri Oct 11, 2013 11:48 pm

Output of the plastic petrol (gasser) fan is a work in progress from my end.

I have worked out how I will mount and drive it for testing purposes but my priorities have pushed this project back a tad.
We will, in time have a comparison. Issue is there is a fair bit of axial pull - would like to chuck it but need to ensure a fan spinning at over 5000 rpm doesn't take off on me.
Agree with Thermorex - the soft start idea is a much better way to go.
I'm afraid a timing belt and other routine/improvements job take priority.

thermorex · **Posted:** Tue Oct 15, 2013 6:27 pm

I installed the fan from the e-Bay guy, with my variable speed controller. So far, so good. It barely starts, runs for 10-15 seconds and then stops. I'm sure the fan is going to be great for normal driving and it may even be OK for towing. But then the temperature outside was mid 60s... Couple thoughts:

- the fan shroud is smaller than our 20x20 radiator. Its more like 17x17 (edit: after a proper measurement, the shroud has 18x18, edge to edge). Which is not a show stopper but I expected a fan with a shroud as big as the radiator.

- the fan it has is a procomp fan, it costs probably 50-ish (edit: after further research, found out it's not a procomp, seems a little better done, not that procomp is not a decent one... ) . Which is not necessarily bad since a spare can be outsourced for cheap.

- the brackets it comes with: it has some guiding brackets on the top which is cool. You're supposed to use a pliers and secure it to the upper lip of the radiator, which I didn't (made my own brackets - read below) . It also comes with that plastic tide-ons that any e-fan comes with, this junk:

The shroud has some holes made in it where you're supposed to insert the plastic ties. I personally try to stay away of stuff like this, don't trust them as I trust a metal bracket. I'd expected a shroud to include some metal brackets in this price. The shroud though has a nice finish. I ended up making my own brackets that I secured the shroud where the plastic fan cover used to be mounted:

Was thinking to make some other one for the guides under, but the fan shroud is so rigid, I dropped the idea.
Those are the upper brackets the shroud comes with:

This is where I installed the probe from the variable speed controller, don't like the idea of pushing it through the fan fins...

And this is the fan controller:

Which once I find the "sweet spot" for when I will ha e it start, ill move it inside the air box, away from dust and humidity.

Overall, I'm happy so far with the purchase, but I paid 260 for the shroud and fan only, plus another 100 for the variable speed controller, plus solder, couplings etc. For some people may be too pricey... Ill follow up wit a mileage report. Jeep feels a little bit more responsive, but may be just my mind playing games...

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Is there a wattage rating on the fan? I like the idea of this if you are not towing or maybe towing less than 2000lb. Roughly $375 is a bit, but if it gives you results in fuel economy if would be worthwhile. I don't think this is a viable solution for heavy trailer towing, pulling grades or desert driving.

You may have to play with the position of the temp sensor for the controller to make sure the fan engages properly and when it is needed.

The shroud not covering the entire radiator means this was designed for a different vehicle and just adapted for the CRD. A full shroud has a significant impact on cooling.

Too bad winter is on the horizon, very difficult to test the limits.

arengant · **Posted:** Tue Oct 15, 2013 11:19 pm

Wow not quite as nice as I expected, I like your other idea of buying a 20"x20" shroud and a fan and using your controller, might have ended up being a lot cheaper since you had to fab up some of your own stuff anyways.

thermorex · **Posted:** Tue Oct 15, 2013 11:23 pm

I'm going to have to do some measuring, but the vendor claims it draws 20 amps and has 265 watts. Cfm 3600 and 3000 rpm. Summit has a 20(wide) x19.5x1.250 deep shroud for about 70-80, which is a little pricey and comes with a 14 inch hole only. Best would be to make my own, as soon as I get some argon...

Regardless, this ff dynamics fan claims also lifetime warranty...

Regarding the speed controller, I agree, I need to find an ideal temperature, starting too soon would be a waste, too late may overheat the engine. Yea, it's hard to see its limits on winter...

thermorex · **Posted:** Tue Oct 15, 2013 11:31 pm

arengant wrote:

Wow not quite as nice as I expected, I like your other idea of buying a 20"x20" shroud and a fan and using your controller, might have ended up being a lot cheaper since you had to fab up some of your own stuff anyways.

Well, those brackets were quite easy to make to be honest, worse was the time I had to spend (about 1 hr with all the measuring). I think I'll ask the seller if he makes the shroud wider, who knows?

Brianawd · **Joined:** Wed Apr 03, 2013 12:59 pm **Posts:** 130

http://www.autozone.com/autozone/access ... 92557_0_0_

http://www.zirgo.com/

http://www.ebay.com/itm/16-INCH-FFD-CYC ... 0746572676

thermorex · **Posted:** Wed Oct 16, 2013 12:12 pm

Yea, the eBay fan is the one, same seller. The only issue that may arise getting another shroud could be due to the depth/thickness, the space between the mechanical fan's axle and radiator is not too big, so some cutting/grinding from shroud may be required.

thermorex · **Posted:** Fri Oct 18, 2013 5:52 pm

Ok, first update: 2 mpg gain, Cleveland, oh - nyc NY. I'm happy with the purchase so far. In traffic in nyc, never overheated, fan started, about a min run, stopped for about 2 min. About 75 outside.

arengant · **Posted:** Fri Oct 18, 2013 7:47 pm

thermorex wrote:

Ok, first update: 2 mpg gain, Cleveland, oh - nyc NY. I'm happy with the purchase so far. In traffic in nyc, never overheated, fan started, about a min run, stopped for about 2 min. About 75 outside.

wow that is impressive gains! Do these gains happen more at slower city driving or cruising speeds?

thermorex · **Posted:** Fri Oct 18, 2013 8:19 pm

Those gains are only highway drive, with maybe 10 miles city drive in Cleveland. Haven't done mileage in NYC, I bet I'd be under 20 since the way to drive in the big apple is floor it, slam the brakes, honk, repeat. The tranny heated to 160 and I had to start the aux fan (I do it manually since I have a different trannyny cooler with custom dual fans). Never seen this tranny that high ever... So bottom line is the radiator electric fan can handle the heat without any doubt! Towing, no idea, but I'm sure is comparable with mechanical fan. Depending on the fan controller one decides to install, there are options to start the electric fan on both temperature and switch simultaneously (switch would be the override). Like a separate coupling for switch on (more for towing) or another sepparate one for switch off (that's for offroad water crossing). All those on the top of normally temperature controlled on/off.

arengant · **Posted:** Fri Oct 18, 2013 9:01 pm

I do about 90% city driving now, and for the next 2-3 years, not NYC city driving, but I rarely get about 45mph. I would think that an electric fan would save a lot during faster driving speeds due to the air flow already being there and being able to turn off freeing up wasted power unlike the mechanical fan. I'll be interested to see how often it turns on in your city driving.

thermorex · **Posted:** Sun Oct 20, 2013 5:19 pm

I'll definitely let you know, but I bet in Hawaii you'd get about a mile a gallon easy since it's hot year round and your mechanical fan would be partially engaged after a few miles. And traffic in Honolulu is horrible... Quite honestly I think it's worth, I would do it without a doubt, I'd probably install that smart variable speed fan controller with a 3 way switch (like up position always on, middle off (let the fan work normally based on what probe sends) and down always off, up and down in this case would be overrides for the controller - 2 "on" - one (the "down") for cutting the fan for water crossing and another one (the "up") to make it "on" on demand, the 3rd way("middle") would be off - for when you want to leave your fan controller do the normal work, aka start/stop based on the temperature you set). I can send you a pic with the installation instructions if you want to see more details, but you can also see it in summit racing link posted above in one of the previous posts. As a matter of fact, I think I'll also follow this approach when I am in the mood for more wiring...

arengant · **Posted:** Sun Oct 20, 2013 5:33 pm

Thanks for the notes! I like the idea of having more control of the fan for sure

mass-hole · **Posted:** Thu Nov 14, 2013 12:15 pm

thermorex wrote:

Ok, first update: 2 mpg gain, Cleveland, oh - nyc NY. I'm happy with the purchase so far. In traffic in nyc, never overheated, fan started, about a min run, stopped for about 2 min. About 75 outside.

How was your stock fan clutch doing? I wonder if that gain would be more or less depending on how effective the stock clutch is.

thermorex · **Posted:** Thu Nov 14, 2013 9:42 pm

Never had an issue with the stock fan, the clutch seemed in very good shape. I also had the hayden on the shelf when I got the electric. Not sure what to say about the gains versus a hayden, since I haven't use one. But I can tell you I constantly get 25-26 city and 28-30 highway, which is1-2mpg gain from before, depending on how long I can hold a constant speed.

jrsavoie · **Posted:** Sun Jun 29, 2014 11:17 pm

Glad I read this thread before ordering the electric fan. I do not have time for a design build. I would be disappointed, when I think I am buying something that will be an easy install. I would not have been happy with the undersized shroud, the way the shroud mounts or the single speed controller.

If anybody comes out with a bolt in variable speed kit, I'd appreciate a heads up. Or if anybody has dimensions to build a shroud and mounts to go with the kit, I would be interested
Thanks

thermorex · **Posted:** Mon Jun 30, 2014 7:08 pm

Jrsavoie, honestly, I haven't had a problem with heating at all. With that shroud, the fan barely starts, Max run time of 1-2 minutes and then it stops. Just get the summit variable speed controller and you're set. The brackets are very easy to make.

jrsavoie · **Posted:** Mon Jul 07, 2014 11:37 am

Is there a possibility of mounting the fan to the OEM shroud after doing some hacking, whcking and rebuilding so opur shroud slides in and out with the fan?

I'm thinking with the fan mounted in the shroud you could pull the whole works straight up.

For now I have done the 2 piece shroud mod.

Electric vs Mechanical fan cfm

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