Electric fan mod for my 3FE

[80JDM]

Hey guys. I'm tearing away at my 91 and thought why would I ever install the belt drive fan? Why not go electric and seize back those 2HP robbed from me by OEM fan?

Fits like a glove. Thank you Mr Hyundai!

 

[jonheld]

No such thing as free power. The belt driven fan will likely move much more air.

 

[80JDM]

No such thing as free power. The belt driven fan will likely move much more air.

@jonheld props to you. No arguing with physics and as usual, my point is half in jest. I'm pretty new around here and I've read enough of your replies to know you are on the ball and up to your elbows in it everyday or used to be at my best guess, so you know all this.
The fan doesn't need to move the air at full blast all the time, only when it counts. As such the engine is not directly contributing to the fan operation. Any load applied to the engine, in this case driving a fan or an alternator charging the battery which powers the fan, I'd opt for the load on the electrics rather than directly on the crankshaft. Same is true for electric water pumps strictly from a theoretical point as recouping that spent HP to roll through the bush and canyons is hardly worth the effort and risk of failure... much better for the track. My electric fan will go through a relay switched by the temp sensor and chooch away at full pin until the temp sensor drops... simple. It could be geeky for no real reason and modulate the fan speed with a simple PWM circuit and have the fan speed directly proportional to the temperature delta i.e. small delta low speed, big delta hi speed.... seems very Lexus.

 

[jonheld]

Those pesky laws of physics
Each time you make a conversion from mechanical to electrical, you're loosing power because the conversion is not 100% efficient.
The mechanical engine driven fan has a fan clutch which regulates lock up based on air temperature. It is constantly varying fan speed.
At highway speeds, more air will flow around the front of the vehicle than will flow through the radiator because an 80 is as aerodynamic as a brick. The fan provides negative pressure behind the radiator to draw air through.

I certainly think you should proceed with your plan, but I would suggest a modern approach to monitoring coolant temps. The 3FE is resistant to head gasket problems, but not immune.

 

[rghouse]

How’d this turn out?

My fan clutch has never been able to keep my 3fe cool enough on hot days idling. I have to switch to neutral and rev the engine up in traffic and at stop lights. Its sad, and stressful. Been my 80s achilles heal. I did all the mods to the FC and it did help a little. I’m now considering trying electric (every mechanic tells me to do this). Or a new radiator. Or seeing if i can tune the idle up at low rpms but not sure thats possible…

 

[Mark W]

Find new mechanics.

Mark...

 

[jonheld]

How’d this turn out?

My fan clutch has never been able to keep my 3fe cool enough on hot days idling. I have to switch to neutral and rev the engine up in traffic and at stop lights. Its sad, and stressful. Been my 80s achilles heal. I did all the mods to the FC and it did help a little. I’m now considering trying electric (every mechanic tells me to do this). Or a new radiator. Or seeing if i can tune the idle up at low rpms but not sure thats possible…

You can't "tune the idle up" on a 3FE motor. 650 RPM is what you get.
Well, you "can", but not without screwing other things up.

On a really good day, the 3FE generates 155 bone crushing horses. The OEM cooling system should have no issues keeping that in check.
I suggest going through the entire cooling system and bring it back to OEM spec.

There are many threads regarding radiators and general tech on cooling systems for both the 3FE and 1FZ.

 

[rghouse]

Im 100% oem except for r134. Anything and everything has been baselined and tested on my cooling system including the head removed and machined. I gave up on trying to figure it out about 5 years ago.