Jeep Cherokee Aeromods - Page 19 - Fuel Economy, Hypermiling, EcoModding News and Forum

Nerys · 12-03-2009, 01:29 AM

hmmm I don't see how that will make much difference. you make the fan more aero just before you hit the brick wall of the engine clock itself?

the point of the CLUTCH is to do exactly what it (flexlite) wants to do. when the fan is not needed the clutch is "looser" and the fan kind of pinwheels free spinning ie almost no engine load. as it gets hotter the clutch tightens up and provides more air.

JeepNmpg2 · 12-03-2009, 02:51 AM

Maybe my issue is a worn out fan clutch, because that fan is anything but spinning loosly when the engine is not at full operating tempreture, and especially in the winter, it really counteracts the vehicles ability to warm itself. So I'm now between a $360-380 upgrade (which I found out from the manufacturer that the Fan Controller I'm looking at is more than capable at handling the maximum draw of my fan).

Christ · 12-03-2009, 03:01 AM

Why do you need all that stuff?

You can get an e-fan from any junk car for $20... check what's being parted out on your local Craig's List site, and get some measurements for your vehicle.

The only other thing you need is a thermoswitch set to whatever temp you want the fan to come on at, usually ~200degF. Wire the fan direct with the switch and a 10A inline fuse to the battery, nothing else is necessary.

JeepNmpg2 · 12-03-2009, 03:58 AM

Two issues

1: Fan must be rated at 4000 CFM+ to be a direct swap for the stock mechanical fan. I run out in the Mohave in the Summer and see 125+ degrees in freeway and stop & go traffic so I cannot accept a decreased cooling capacity

2: 85 AMP startup draw which with the fan only cycling on for 5-10 seconds under normal conditions and off for a minute, will prematurely wear out the fan motor and whatever relay or continous-duty solonoid.

I still contend that the fan controller is the "ideal" setup, though I wholeheartedly agree with not throwing tons of money at this unless no other truly viable long-term option exists.

Christ · 12-03-2009, 04:02 AM

I don't think I've seen a radiator fan that draws 85A on startup... that's ALOT. In fact, they're usually wired with 14G or 12G wiring, which doesn't like 85A.

I think you'd find that you actually could deal with somewhat decreased cooling capacity, but that's not an argument, if you don't want to decrease, you don't have to.

Check on fans that are used for reefer units, they'll surely have the capacity you need.

Nerys · 12-03-2009, 08:38 AM

Cherokee's DO RUN very hot. in fact they are designed to run just under boiling a 210'

they are just hot critters so adequate cooling especially in 125+ desert running is critical.

maybe you could use lesser fans if you used 2 of them? one in front and one behind the radiator? have one kick on at one temp and the other kick on at a slightly higher temp (this way if you need just a little cooling only the one will come on but when its really hot both will kick)

eco_generator · 12-05-2009, 05:22 PM

Quote:

Originally Posted by Nerys

the point of the CLUTCH is to do exactly what it (flexlite) wants to do. when the fan is not needed the clutch is "looser" and the fan kind of pinwheels free spinning ie almost no engine load. as it gets hotter the clutch tightens up and provides more air.

That clutch may get "loose", but it is still drawing loads of parasitic power. It can soak up 5hp before the fan even begins to turn. I got rid of one on my Subaru wagon, with 95 hp and loaded with work equipment there was not a whole lot of extra horsepower to just lose in a fan. I took it off (it also has an electric fan) and the extra power was immediately noticeable.

So losing the clutch fan is a win/win. You will save gas just from not turning that clutch all the time.

Nerys · 12-05-2009, 05:39 PM

wow. did not think they consumed so much power.

eco_generator · 12-05-2009, 06:22 PM

I was shocked, also.

Christ · 12-06-2009, 12:37 AM

Yeah, anything that requires a fluid drive is fairly lossy. Fluids are quick to thermal transfer, usually, and the heat energy has to come from somewhere, right?

What a clutch fan is doing is leveraging airflow against heat energy. If the air is denser than the amount of power being transferred, the fan doesn't speed up, which heats the fluid, which gets thicker, forcing the fan to turn through the air. It's a net waste of energy in any sense.