yes, many 1200s with cooling problems have been fixed by putting the stock mechanical fan back on.

An 80 amp alternator typically has trouble with belt slip (with single old style v belt) on some apps. 80 amps x 12 volts = 960w . So even assuming a perfect energy conversion, the belts themselves have trouble with 1kw, let's say 50% conversion, the belts have trouble gripping with a 2kw load. SO I'd be tipping that that is about the most a mech fan can sap without the belt shredding in the first place. I know that's terribly backhanded (about as clean as I can make the original phrase) sort of reasoning, but it's worth noting.

I've always had the 'if it ain't broke' approach to most things, and a mech cooling fan is one of those things I think work well. I'd not swap to one if the car came with an electric fan mind you, but I'd be wary of their use otherwise. Playing devils advocate however - on highly modified minis cooling is an issue, the factory fans are so-so and the air has to go in from the front, and then out the side toward the passenger side wheel, which isn't where most of it wants to go at decent road speeds (meaning you don't get proper high speed airflow through the rad at high road speeds). On that application, a dc-31 fan happens to fit well in teh wheel well and transforms the otherwise borderline radiator physical dimensions into a workable proposition.

Quote:

Hi Tom
I would be really interested to see some actual, measurable data on this.
Please let me know the outcome.
Regards Matty

My guess would be 1-2 HP but when I go back to the Dyno if time permits I'll pull off the standard plastic fan.....it takes me all of a minute to do..................would be interesting to see what the difference in horsepower.

Tom

standard A-series fans 310 mm



factory clutch fan thermostatically controlled



factory electric fan from Pulsar N11

im a big fan of the thermo

noticable power diffrence between mechanical fan and switched off thermo fan

they are hardly ever required to run if you have a well maintained cooling system

definately go thermo

especially when you consider bang for buck, $50 for 5 HP, thats as cheap as it gets!!!!

people spend thousands getting compnents lightened and balanced to reduce windage in the sump and inertia of the drivetrain.... having a fan hanging off the front of your motor is pretty much a mortal sin considering this

I have a stock Datsun 1200 fan shroud. It doesn't seem to make any noticeable difference.

I just bought a 10" electric fan with a rating of 1550 CFM.

I dont know if i will use it or use the original one.

Has anyone ever built a fan shroud for the stock fan to get it to be a bit more efficient? Thinking of fabbing one up at work and bolting it on with my new rad.

Thanks DD I do mean the fixed A12 fan.

Quote:
Do you mean the B310 clutch fan used with Air Conditioning? The standard fan is a fixed fan, and has no clutch


...to a 10" thermo

The B310 clutch fan is thermo controlled. It spins more freely when cold and less free when hot. It is 350 mm diameter - steel, 7 blades.

Nissan thought it is was important enough to use instead of the standard fan. My guess would be as much as 5 HP at 6000 RPM for this fan if not using a clutch.

The standard 310 mm diameter plastic fan takes what? 1 or 2 hp?

For the best savings, use an electric fan like that used on N10 or B310 models. That can save 100% of the fan power when the fan is switched off. It only runs when the engine needs it. Electric fan: 320 mm diameter, steel 5-blade (some 1980-1982 B310s)