Big Block Cooling w/Electric Fans: DON'T DO IT

[Bextreme04]

The OEM started to use electric fans due to emissions requirements. If they didn’t have to meet such extreme emissions, they would probably still be using mechanical fans. The advantage of electric fans is more precise control. The ORM have to meet demanding cold start emissions, anything that can be done to get the engine warmed up as fast as possible is worth the effort. Electric fans don’t do anything until the PCM commands them on. A thermal fan clutch still spins even disengaged, it still draws airflow thru the radiator, and slows engine warmup ever so slightly.

As far as mechanical fans robbing power, I say ********. I base this statement on some testing I did a few years ago. I was at the dragsrip with some friends on a test and tune night when the typical bench racing started. I like my cars with the kinda stock looks, even though very little is factory. The aftermarket go fast stuff I have added is either hidden in plain sight, or just not obvious. One of my buddies commented on the factory fan wasting power, I argued that unless the clutch is engaged, the fan isn’t doing much. To test my theory, I made a couple passes with the car as I normally run it, just to establish a baseline. I then removed the fan and clutch, and made a couple more passes. The E.T. was basically the same, the mile per hour did go up ever so slightly. There is zero doubt in my mind thermal fan clutches consume a slight amount of power, but certainly not the 20hp people seem to think they do!! In my opinion, the .04-.05 loss in mph is well worth never having to stress over engine temp. The hottest I have ever seen the Olds get is about 205, this was in bumper to bumper traffic, in 90*heat, with the A/C on.

Both of these are tied together. Emissions, fuel efficiency, and power robbing are all related. It takes energy to move the air... period. The idea that it doesn't take any power for the fan to move the fan is just nonsense, it is mechanical energy. The reason they went to electric fans is the same reason they went to more precise alternator control and DOD/AFM. The EPA requirements added minimum fuel economy requirements that hit the manufacturer with "points" depending on the average fuel economy. Running a mechanical fan at freeway speeds where you don't need ANY fan at all turns out to be a fairly significant parasitic drain.

Here's an actual factual analysis of just how much drain those fans have... rather than just anecdotal, seat of the pants type analysis. I agree it is probably peanuts on a race car making a 1/4 mile pass. For cruising on the freeway, where the engine is only really making ~100hp or so to keep the car moving, it can add up fast.

https://drivemag.com/video/cooling-fan-shoot-out-engine-masters-ep-20

I agree with this. A guy has to drop a darn good bit of money to even get a mediocre aftemarket setup. Look at the CFM air flow of a $200 aftermarket setup vs a factory 5 or 7 blade fan. IMO the only reason new vehicles have gone electric is fuel economy and possibly because they can be better controlled by the computer though Ford did use an electronically coupled mechanical fan at one time, the electronic coupler was controlled by the PCM and took the place of the thermoclutch connected using clockspring style contact set.

I got the entire electric fan setup... including the fans, relay box, wiring, connectors, etc.. for about $75. They are all over every junkyard around here. Its getting harder and harder to find any metal OEM type fans. The 9 blade that came on the heavy 454's are completely unavailable and a new fan clutch would cost just as much as the entire electric fan setup.

 

[Vbb199]

Here we are fine tuning our cooling methods, and I'm over here with junk I threw together that I had lying around.... a 4 core aluminum radiator with no shroud, homemade radiator clamps, and a 6 blade flex blade fan, running at 200-210 on my 502 ci lol

I intend on electric fans when the time comes though. It's just temporary, and stays reasonably cool idling or raising hell.



Point being: this is some good info to save for later.
Because I definitely intend on a better cooling system

 

[Bextreme04]

Here we are fine tuning our cooling methods, and I'm over here with junk I threw together that I had lying around.... a 4 core aluminum radiator with no shroud, homemade radiator clamps, and a 6 blade flex blade fan, running at 200-210 on my 502 ci lol

I intend on electric fans when the time comes though. It's just temporary, and stays reasonably cool idling or raising hell.



Point being: this is some good info to save for later.
Because I definitely intend on a better cooling system

Well, at 150mph I don't think the fan is doing you any good Vince

 

[SirRobyn0]

so did GM

I don't remember it, but have no doubt it's true.... Was it like on the 6 cyl in the trailblazer?

 

[AuroraGirl]

I don't remember it, but have no doubt it's true.... Was it like on the 6 cyl in the trailblazer?

I believe TBI/LT1 wagons with tow packages but if not that, im sure the 6 cylinder on those are equally plausible

 

[SirRobyn0]

I believe TBI/LT1 wagons with tow packages but if not that, im sure the 6 cylinder on those are equally plausible

After you said it I kind of feel I remember seeing them on some GM SUVs as well. The reason I really remember them on the expeditions and excursions is because the wiring was held by a thin brittle plastic channel, and guys would break them working on the the belts, resulting in an inop, fan clutch. Ford's system would not set a check light for that so the driver would only know there was a problem once it overheated.

 

[AuroraGirl]

After you said it I kind of feel I remember seeing them on some GM SUVs as well. The reason I really remember them on the expeditions and excursions is because the wiring was held by a thin brittle plastic channel, and guys would break them working on the the belts, resulting in an inop, fan clutch. Ford's system would not set a check light for that so the driver would only know there was a problem once it overheated.

You must be registered for see images attach

it appears you guessed right

 

[SirRobyn0]

You must be registered for see images attach

it appears you guessed right

Yes, Trailblazer is on there. I don't remember ever having to work on electronic fan clutches on those though.

 

[bucket]

Yes, Trailblazer is on there. I don't remember ever having to work on electronic fan clutches on those though.

I had to do many of those. I hated them. Every step of the way was frustrating because some engineer decided to leave just slightly not enough clearance to remove any one part without first removing another part. Just like many other areas of those rigs.

 

[SirRobyn0]

I had to do many of those. I hated them. Every step of the way was frustrating because some engineer decided to leave just slightly not enough clearance to remove any one part without first removing another part. Just like many other areas of those rigs.

I agree. I have a friend who is a mechanic and loves working on difficult jobs. When he bought a trailblazer I thought oh my, and then well he be fine with removing 6 things to do one job, he'll probably enjoy it!

 

[AuroraGirl]

I suppose in a trailblazer with a 4.2 that leaves so much room in front of the thing while if its a 4.3 its got so much room around it Lol...