Advantages of electric cooling fans vs mechanical

[BobbyB]

Can anyone share some real world drag strip numbers from mechanical to electric fan?

[GARY C]

Can anyone share some real world drag strip numbers from mechanical to electric fan?

I don't know about on track but EMC tv did a water pump and alternator test and was down on power by 6 ft lbs and 11 hp they also did a fan/radiator and shroud, the clutch fan was down 7 ft lbs and 15ish hp, the factory flex fan lost 30 hp and the thin blade flex fans were down 20ish. Their fan test did not include an alternator so that would be another 5 or 6 hp lose.

[n2omike]

I thought you watched Engine Masters TV?

My biggest issue with elec and street is that few do the job.

THIS. Mechanical fans cost a TON of horsepower. The test they did on Engine Masters didn't even spin them that high, and they still ate a BUNCH of power.

A STRONG electric fan and good shroud WILL cool a street engine just fine. You just have to buy a good one, and make sure it's sealed to the radiator, and draws across the majority of the core.

Another bonus, as has been said... is that you can turn it on and off. These are invaluable at the track. Couple an electric fan with an electric water pump, and the engine can be cooled down to room temperature in just a few minutes. (especially if you remove the thermostat for the track session)

A Derale 16926 fits a 1966 mustang like it was made for it. It's a fan/shroud combo. The sucker draws 20+ continuous amps, and blows like a hurricane. Zero problems with cooling on the street, and I'm even using an old Moroso electric water pump drive that spins the stock water pump! I did use the 'overdrive' pulley. Have used this setup for decades and thousands of street miles without issue. Radiator is aluminum and has two 1" cores... but otherwise, stock dimensions. Fan is only 3-1/4" thick. The right fan makes ALL the difference.

[BobbyB]

A Derale 16926 fits a 1966 mustang like it was made for it. It's a fan/shroud combo. The sucker draws 20+ continuous amps, and blows like a hurricane. Zero problems with cooling on the street, and I'm even using an old Moroso electric water pump drive that spins the stock water pump! I did use the 'overdrive' pulley. Have used this setup for decades and thousands of street miles without issue. Radiator is aluminum and has two 1" cores... but otherwise, stock dimensions. Fan is only 3-1/4" thick. The right fan makes ALL the difference.

N2O,
Is your fan between the engine and radiator or between the radiator and grill? Do you have to do anything special as far as upsizing your alternator?

[rebelyell]

Seems many diesel OTR trucks have Belt-driven fan clutch that is switched on-off electrically. Dunno if something like that could be practically integrated?

[n2omike]

Is your fan between the engine and radiator or between the radiator and grill? Do you have to do anything special as far as upsizing your alternator?

The fan is a puller, and is installed between the radiator and the water pump. There's about 1/4" of clearance or so between it and the tip of the water pump.

As for an alternator, I use a 3G alternator. I got one off an old 90's Taurus in the junkyard years ago for $30, and have been using it ever since. If you can, get the wiring harness pigtail and bottom tightening bolt, as it's metric. It bolted into the stock 1966 mustang mounts with no issues, and I was able to put a standard fan pulley on it. The wiring is EASY. You basically run a big wire from the main lug to the alternator, and the only other wire is one that is powered when the ignition is switched on to activate it. Below is a wiring diagram. It makes it look more complicated than it is, and tries to cover any possible 'gotchas'. Top pic is the basic install... and all I had to do.

These alternators produce a TON of current, and do it at a very low rpm. Even with a small crank pulley, I could run headlights, water pump, fan, electric fuel pump, etc... at idle... at night... and not discharge the battery. Simply amazing.

[GARY C]

Another option I have seen done with elec fan and alternator is to run a wide open throttle micro switch that disables the alt to stop any power lose it may present.

[digger]

i'd look to retrofit an OE electric fan over an aftermarket one as the aftermarket ones seem to be fairly under powered

Very much this!!!

OE fans tend to flow on the 3000-4000cfm range and have BIG, BEEFY motors that can power those aggressive blades to pull air through the cooling stack at high pressure drops.

I laugh when I see "2000cfm" fans with straight blades, hardly any shrouding, and a 15 amp fuse on little 16 gauge wire. A real fan will need a 40 amp circuit per fan and have cabling that looks like it belongs on an alternator.

Ideally the fan will be well shrouded and be about one fan hub diameter's distance away from the radiator, too. You want the fan to pull from the whole radiator instead of a 16" circle.

some of the newer BMW fans are 850W for a 450hp engine which at 12V would be 70 Amp?

[peejay]

i'd look to retrofit an OE electric fan over an aftermarket one as the aftermarket ones seem to be fairly under powered

Very much this!!!

OE fans tend to flow on the 3000-4000cfm range and have BIG, BEEFY motors that can power those aggressive blades to pull air through the cooling stack at high pressure drops.

I laugh when I see "2000cfm" fans with straight blades, hardly any shrouding, and a 15 amp fuse on little 16 gauge wire. A real fan will need a 40 amp circuit per fan and have cabling that looks like it belongs on an alternator.

Ideally the fan will be well shrouded and be about one fan hub diameter's distance away from the radiator, too. You want the fan to pull from the whole radiator instead of a 16" circle.

some of the newer BMW fans are 850W for a 450hp engine which at 12V would be 70 Amp?

Sure.

On one of my cars, I have the fans from a Chrysler 300M. There are two, two-speed fans, meant for an undersized radiator with no room for air to escape behind it, so they are well overbuilt. Any time you have two fans in the same shroud you MUST run them at the same time to make sure air doesn't short circuit backwards through the nonrunning fan. Anyway this meant that "low" and "high"' on each fan were tied together, and each was routed through its own 40 amp circuit! I thought that was overkill, and used a (much cheaper) 30 amp rated fuse holder and relay for each speed. They started burning out at a rapid rate. Spent the money for the proper hardware and no more problems.

With the fans on high, they draw an honest 75 amps. It's rather interesting to have your idle speed pulled down 300 RPM by switching the fans on.

My go-to when there js room is the 2013 GT500 fan. It WILL cool down a 600hp engine no problem. Best of all it is fairly cheap and remarkably quiet for the amount of air it pulls.

[digger]

Seems many diesel OTR trucks have Belt-driven fan clutch that is switched on-off electrically. Dunno if something like that could be practically integrated?

it seems like an AC electromagnetic clutch would be the way to go to disengage and engage a mechanical fan as required?

[dannobee]

The big diesel truck fans are indeed belt driven but are controlled by compressed air. If you've ever priced just the clutch, you'd eliminate that from any part of this equation.

I agree with just going to the junk yard and picking up the fans and shroud off of practically any V8 powered car. Don't forget to grab the relays and the harnesses at the same time.

On some of the GM big block 3500 series trucks, even the engine driven fans didn't flow enough air when pulling heavy loads up hills and there was a bulletin out to install a pusher electric fan kit on the front of the a/c condenser.

On the Gen3 Camaros, it was common to see them come in the service drive missing the lower air dam (just below the radiator). When we'd ask them if was there for overheating at freeway speeds, invariably they' ask, "How did you know that??" Make sure all of the ducting and deflectors are in place, even if you don't "think" they do anything.

Don't forget that when idling in traffic, the electric fan will likely move more air across the a/c condenser than the engine driven fan when not locked up. It could add an element to the equation if you live in a hotter area of the country.

[peejay]

Seems many diesel OTR trucks have Belt-driven fan clutch that is switched on-off electrically. Dunno if something like that could be practically integrated?

it seems like an AC electromagnetic clutch would be the way to go to disengage and engage a mechanical fan as required?

The way the OEMs do it is with a PWM controlled clutch in the hub, so they can control the amount of lockup to a precise degree.

That still does not allow you the largest advantage of an electric fan. Like an electric water pump, it can work at 100% at idle or lower engine speed because its operation is not tied to the crankshaft. You don't have to sacrifice idle/low speed cooling to be effective at the top end, or vice versa.

[70GS455]

Use both, if you have room. Dakota's and Rams of a few years ago had both. Electric puller was inside the shroud and used only when needed, mechanical was clutch driven. You could hook up a toggle or temp switch. Or install a pusher in front