Tuning for e-fan conversion?

[Schurkey]

You think a fan/fan clutch takes 10--15 horsepower "off the top" when it's not engaged?

And when it's engaged, the air flow produced is likely MUCH greater than a pair of electrics when the engine is revved-up. But that would depend on the size/power of the electric fans; the diameter, number of blades, and blade pitch of the clutch fan, and the type of clutch.

At idle...yeah, the electric fans probably move more air.

 

[Erik the Awful]

You think a fan/fan clutch takes 10--15 horsepower "off the top" when it's not engaged?

Engine Masters season 2, episode 20. A clutch fan takes 15 hp when freewheeling. The old style always-turning fans rob 33 hp. I'll give that up for reliability on a truck that's not going to see the track but maybe once or twice.

 

[df2x4]

^ I was about to post that info from Engine Masters but Erik beat me to it. I don't recall them mentioning whether the clutch was engaged or not when they recorded the dyno run, but I know the clutch fan robbed 14-15HP.

 

[Erik the Awful]

They were running it on the dyno with a radiator and shroud mocked up. The water pump was running through the dyno's cooling system, so no, the clutch wasn't engaged.

 

[kennythewelder]

Here is the thing. The OP asked about electric fans and tuning for electric fans. Not what you like better or don't like. If electric fans work for you grate, if they don't, that's still grate, but stating your case as to why you think they suck or not, is really not nessary. If you like electric fans, then run them. If you don't like them, them don't run them. Going back and forth about electric fans VS mechanical fans, is not helping the OP at all. It's the OPs truck, let the man run what he wants to.

 

[El Tigre]

Suit yourself , but I sure don't buy into the idea that electric fans are unreliable.
My '96 Impala still has the the pair of fans it came with. The truck's dual fans flow air through radiator down each side of the motor. Compared to the engine driven fan that
sits 6-8" in front of a fairly large object that clearly blocks a significant amount of air.

 

[df2x4]

The OP asked about electric fans and tuning for electric fans.

On that note, can the '96-'97 black box PCMs in these trucks be tuned to control e-fans? I've seen PCM control mentioned many times here but I'm not sure if it's a '98+ or 0411 only thing. Can anyone shed some light?

Personally if I were going to do e-fans I'd prefer that the PCM and existing sensors controlled them instead of an aftermarket temperature probe setup.

 

[Schurkey]

This episode?
www.youtube.com/watch?v=Os_Hna9DZa8

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I have to watch with the sound off, maybe I'm missing something...but...what I'm seeing in the corner is that when they remove the shroud, they claim to "gain" 8.1 horsepower, and 0.7 ft/lbs of torque.

I'm guessing that the dyno is not repeatable to "0.7" ft/lbs. It might be repeatable to 3 or 4 horsepower. They're falsifying the accuracy of their results.

And at any rate, removing the shroud is not testing fan clutch engaged vs. disengaged. If the test was done the way I think it was, with the shroud, the fan clutch may have been warm enough to engage. Without the shroud, it probably would not have been warm enough. IF (big IF) that's the case, we're looking at the worst-case-scenario--a functioning fan inside a duct vs. a freewheeling fan in free air. So at best, the difference is on the order of 8 hp, plus or minus due to dyno repeatability.

I have some doubts about a straight mechanical fan taking 33 horsepower to spin. I don't think the belt will transmit that much power, and there's still the load from the A/C, PS, and alternator. I ripped a serpentine belt apart with the starter motor on my Trailblazer, when I tried to crank it after the A/C compressor bearings locked-up.

 

[df2x4]

@Schurkey That's a short video they made after the original episode, here's the full episode.

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[L31MaxExpress]

You think a fan/fan clutch takes 10--15 horsepower "off the top" when it's not engaged?

And when it's engaged, the air flow produced is likely MUCH greater than a pair of electrics when the engine is revved-up. But that would depend on the size/power of the electric fans; the diameter, number of blades, and blade pitch of the clutch fan, and the type of clutch.

At idle...yeah, the electric fans probably move more air.

Duramax fan cost me 10 hp and 15 tq when it engaged on the 4th pull on the dyno in 90°F heat. Freewheeling it cost less than 2 hp compared to E-Fans that were off at the time. That is a massive fan with very steep blades and 33% underdriven. Basically setup the fan to turn Duramax like speeds. Pulled alot more air everywhere than the Tahoe electrics did, even at idle.