The only reason Id ever want an electric fan would be to run it with an electric water pump while my engine is off and Im sitting in the staging lanes at the track.

 

Well, I've never had the Ram temps go beyond mid-gauge, so no experience there.

But, the PT Cruiser, another story. 2-speed fan, the controller turns the fan on at high speed anytime the A/C is on. This happens even if the controller is happy with the fan off without AC. When I bought the car, the HS fan never came on, although I didn't know that right away. LS fan works fine.

When things are working right temps rise pretty quick in this car, get to mid on the gauge, and stay there. Summer, Winter, whatever.

In stop-and-go traffic, with A/C on in 60F ambient or above, you can get hung up in traffic with the gauge at mid. In about three minutes without that HS fan setting going, it will be at "shut this thing down now"; you can actually see it rising in a 1-minute stop at a traffic light with just the low speed fan setting active.

First time it happened I knew to hit the heater at full blast to remove some heat from the cooling system, roll down the windows in your hot summer day temps, and pray. Maybe it was the prayer, but it worked and temps started to drop.

I hunted down the issue (apparently common on PTs) and got it fixed, although not before waiting for a cheaper solution than going to the dealer and paying $700 for a new fan. Plus labour.

So I did get to see some driving and check out the behaviour. The heater trick was enough to keep it sane if I got stuck in traffic in the meantime, although far from comfortable.

Above 40 mph you can do whatever you want; it will not move from mid, or if it does move, it moves down a bit. If you are at high temp on the gauge and get some open road, it takes only a few minutes driving to climb down to mid from "time to panic now". Like 2 minutes.

I have to assume mid is at 195F, the thermostat opening temp, but it could be slightly different, not much. There's no numbers on it.

Fixing the HS fan problem solves this issue completely. Air and stop-and-go, temps in the 90's or even above, and it stays rock steady.

With regard to load, although the alternator might work fine at high load, and you might think after 6 months no problem it's a non-issue, it will quicken it's failure.

Maybe it takes 3 years, but you will be replacing it sooner or later. Ideally you want a low duty cycle at high load, which generates heat and that kills the alt eventually.

That should not be taken to mean don't install an electric fan, just pay attention to the load of the fan you're choosing. Also there are plenty of situations where the alt is generating power due to the RPM it's being driven at, and the power is greater than your load, so it dumps the excess power.

You could be using that power driving the electric fan instead without causing excessive load or increasing the parasitic loss as much (the alt has higher parasitic loss with higher load).

Basically the alt is capable of generating a certain amount of power at it's minimum parasitic loss, but will increase that loss when a greater load is put upon it.

If you have an electric with a high load motor, you can manage the load with an add-on controller so that it's only working hard when absolutely necessary.

Now I have too many damn cars to remember which one this applies to, but somebody is using junkyard OEM Mercedes fans because they are high output and relatively low load motors, the shroud fits, and they are cheaper than the alternatives. Off the V-8 Mercedes cars. High Quality Brushless motors and there is an aftermarket variable speed controller that just uses a temp sensor to decide what to do next. I think it's for the PT.

A good shroud makes a world of difference in the fan's ability to cool the rad. Worth paying attention to.

I don't think the electric fan being pushed by road speed to spin faster is really an issue. It might if the fan was also trying to cool the motor at the same time, but I can't see that condition lasting for long on a street truck at speed. Maybe towing in really hot air, though, or if there is an underlying cooling system problem that should be corrected anyway.

As an electric motor's speed increases, it increases it's ability to resist external forces acting upon it to change speed through back-EMF.

As to whether a shop fan driven by a 1.5 HP motor is indicative of the most HP gain possible, well, the shape of the blades and the pitch are what mostly determines how much power a fan uses. That's why turbine aircraft use constant speed props ... they vary the pitch to apply different power levels, from near zero to full engine power. Propeller speed remains constant.

Variable pitch is exactly how a flex fan lowers the parasitic HP demands of the engine fan.

On the other hand, on an outboard motor which has a fixed pitch and shape, changing the prop for one with a different pitch affects loaded HP, acceleration, and top speed. The engine RPMs at WOT cruise will change noticeably with a pitch change of 5%. So, clearly, you could alter the power the clutch fan uses with just a pitch change alone.

This means we have no idea how much power the stock clutch fan uses, so you can't say that there can't be more than 1 HP available with a modification to a more efficient fan.

 

Wow, someone needs to take their fluids class again. Blades "catching air" is the most technical usage to explain how lift works, I guess.

 

Hate to tell you dude but on some of these trucks the pulley comes already on the pump and is NOT bolt on. If you like I can post a pic of mine.

Just wondering but did your mama not hug you enough as a child or what? Just curious where the EXTREME attitude is coming from...

 

I think his plenum gasket is blown.

 

Lol dude

 

Then why the F are you here? Go back to Dodge Talk or wherever the hell you came from. If you can figure out where that is ("if thats possible with an IQ like that"). I predict that buy the end of the day you'll be banned and we will no longer be blessed with your genius presence and we can go back to fixing all our members problems by replacing the plenum gasket. Oh and btw, welcome to DF.

 

Correction, it's genious****

 

Woops, just meant to say "blessed with your presence" and delete the "genius" part. Hey bud, I never claimed to be a "genius" to begin with.

 

Lmao. Dude THAT was funny!