SeanR

The Forgotten On

Huh. Interesting...

Speedtoys

Ya know.

Is this how you react to help in your day job?

Ducman82

Being our cars don't have a "constant or direct drive fan" what's the point of which fan is "better"? Numbers are cool (pun intended)... but I do see how they are relevant here In practical use.

Speedtoys

"The aluminum fan is lighter than the steel and plastic version as a point of fact."

So what, its cheaper. (Cast -vs- injection moulded) Who cares what it weighs. It's not a "lightweight" platform. (Cast -vs- injection moulded) . Want the car to be lighter? Take up a spinning class.
Flow is..speed related, but because its a clutch, speed is also drag related. To put that in terms you'll easily understand, its very comparable to the operation of a fixed pitch propeller -vs- a constant speed one...where pitch isnt changing based on power potential, but speed is via the clutch slipping based on it's temperature. Im sure you grasp that. Input potential, drag, balance of force..and output.

I could have my 19yr old daughter explain this to you, too. She actually know all the right words. I'd stop assuming what you think you know and believe.

"if the respective fans were bolted to a direct drive test rig at the same rpm"

If this were a 66 Pontiac, we'd care. But the only way thats going to happen, is if you have a failed fan clutch, and breaking more things is a goal.

Its an interesting question, but the answer doesn't exist on a 928, and doesn't matter anyhow. Thats how a viscous clutch works..it removes that problem. There's no point in moving useless air, at the expense of NVH and HP.

WALTSTAR

Speedtoys, you have a keen way of going on unrelated tangents having nothing to do with the queries and also seem to like to attempt invalidating peoples intelligence. I see you must have a irrepressible need to do so.
There is no mention of clutches, AC fans or the like in my question. It was as simple as I could make it, but the responses from you go in all kinds of directions while surmising that the questions are irrelevant. The purpose of this forum is to share (or so I thought).
You enjoy yourself and have a good day.

Jim Devine

The 86 fan together with the smaller fan pulley ( additional capacity for cars with rear air) and a fan clutch in good shape is the best you can do for belt driven fans. The next year they went electric. Porsche didn't update the fan from metal to plastic for no reason. Don't have the p/n or size for the smaller pulley, anyone?

Speedtoys

Well, even all electric, they employed a silly amount of engineering to NOT run the fans more than they had to be (speed) based on temperature.

Jim Devine

Sorry, forgot to be specific- post edited/ corrected- that combination was the best they offered for belt driven fans, which was the original topic,

WALTSTAR

Thank you for proving my point!

dr bob

the number of blades, the shape and the pitch are related to both flow and noise. Aluminum pieces are much more prone to fatigue failure and may be more expensive to make than the plastic pieces. Meanwhile, the clutch lockup percentage is related to temperature behind the radiator. The response isn't instantaneous, but isn't far behind demand in the big picture. There's a reason why electric fans have become popular, and that's so they fans can actually stop when not needed.

-----

The condescending tone in some of the posts serves no purpose. We share knowledge and experience when we can, to speed the learning of others following along with us. There's no benefit except to ego when the discussion strays to include negative items not related to the questions. Think "golden rule".

hacker-pschorr

The fan clutch recently shot craps in my 2003 Denali (yes, a 2003 truck with a 6 liter V8 with a 9,000lb towing capacity has a single belt driven fan with a clutch just like early 928's with zero over heating issues. Remember that the next time anyone thinks an electric is automatically "better").
Anyway.... I had the choice of a standard, super, or heavy duty clutch. The 6 liter comes standard with the super so I suck with that. Holy hell...my original one must have been going bad for quite some time. I never heard my fan before and now even with the windows closed I can hear the "WOOSH" of air as I accelerate with a cold engine.

Made zero difference on the engine temp, only helped fix my lack of A/C at idle. No front mounted pusher either.

Back to the electric vs belt fan. Browsing the forums I thought about an electric conversion instead of buying a clutch. There are kits out there but they also require a new alternator (unless your truck was equipped with the HD one, that might suffice).
Point is, the 145amp alternator isn't enough to power an electric fan that can do the job of the standard belt driven one.


That being said....my 79 is running a single S4 fan since after much testing, that's all that car needs...... The US 16V's are ridiculously easy to keep cool if everything is operating correctly. Yes it has a colder thermostat with lower temp fan switch.

captainOCD

Funny you mention the heavy duty clutches. About 6 years ago when my Durango needed a new one all you could get without buying a mopar one was heavy duty, and all of those engaged so much of the time and so aggressively that they made the thing sound like a garbage truck. I ended up going to an electric fan setup mainly because it was cheaper than the mopar clutch, and it that particular case, a far better cooling solution.

WALTSTAR

I see similarity in thought relative to my "thermal factor of safety" statement in a previous post. Your running a cooler stat and lower temp switch is indicative of said "factor" in my eyes.

WALTSTAR

Thank you, Dr. Bob. You have always been a scholar and gentleman. Too bad there arent many more of us around.