slickfx3

to electric or a flex fan?

bashcraft

The clutch fan won't use any more power that the alternator will use to drive the electric fan.

worship79

The clutch type only engages when too hot, so that's pretty efficient. I replaced my because it needed replacement and went electric just for the fun of it.

gungatim

flex fans have generally been shown to be much less effective than stock clutch fans, from the articles I have read anyway...

switching to electric has it's benefits, but you're still going to be converting mechanical energy into electric, so you're only ahead if/when the fan is turned off, which will be rare when it's running.

SI67

My understanding is that for an engine that's pretty much stock, a properly operating clutch fan is excellent for effective cooling and efficiency, but I do have a question about your comment:

If the ON/OFF temperature (assuming it's controlled by a thermostatic switch) is appropriate, wouldn't the fan motor generally be OFF at highway speeds?



Steve

bashcraft

Yeah, and the clutch fan will also be free wheeling.

mikem350

Generally yes. BUT my car runs a little cooler with AC on with the fan on (via a manual switch). Also all the radiator seals are needed, especially the one at the top of core support to "ram" all the air through the radiator!

Easy Mike

Next to nothing.

Your 82 came with a factory electric auxiliary fan. All 82s had them.

gungatim

yes, it SHOULD be, if there is enough air moving through and all seals etc. are intact, but nobody drives at highway speeds all the time, you start the car, idle, stop at light, drive to the dairy queen, stop to pickup a hitchhiker, etc... highway speed is not where you need power anyway, it's getting up to speed or racing around town

alternatively people just use an on/off switch, I've even seen some always on with ignition...not how I'd do it but it happens...if you were planning to race and needed that last little bit of power, you might turn the fan off while doing a run then back on when it's done maybe...

Torqued Off

Silliness...it is not measurable unless you are racing.

Unforgiven1

My opinion: Yes, electric fan. The mechanical fan uses horsepower, adds mechanical complexity, and induces stress on the water pump. Pull that enormous fan shroud off while you're at it and save some weight/add room.

Torqued Off

How much real HP do you think it uses, and could anyone tell the difference.

Add ELECTRICAL complexity, which includes if electrical fans, wiring or power fails you are done, as opposed to a fan mechanicially connected to the engine...if engine runs, fan will run.

Weight...again, does it really make a difference.

I know its fun to make performance improvements, but unless you are really racing the car, its all just a waste of money....BUT, we own our cars, and we can do anything we can afford to to. Many people believe that lots of mods are trying to fix things that are really not broke. Chevy 350's have been built by the hundreds of thousands, with mechanical fans, hardly see why we need to outsmart that.

Unforgiven1

I'm just a fan (no pun intended) of technology, especially where engine management is concerned but also with regards to cooling systems. I run a 94 Camaro/Firebird radiator with electric fans in my 1980 with none of the foam around the core support and I've never had a problem keeping it cool. I've deleted mechanical fans on Chevy Trucks, Astro vans, Jeeps of all types, Chevelles, Cutlasses, and probably a few I've forgotten. I don't miss the roar on start up or worrying about tangling with the damn thing while working under the hood with the engine running.
Besides, when are you driving a Corvette and not racing?

AboveTheLogic

Not having that huge and annoying shroud in the way is definitely a benefit. When I bought my C3 a couple of years ago the shroud was missing. Used shrouds in mediocre condition on ebay had bigger price tags than the electric setup I have with a fan shroud that I made out of a large baking sheet. Looks better, easier to get to things, no regrets.

lionelhutz

Finding decent back to back test data is difficult but here are a couple of links to check out,

http://www.carnut.com/ramblin/dyno.html

http://www.network54.com/Forum/21565...+Fan+Dyno+Test

To switch, you also have to make sure your charging system is capable and you have to implement a proper control scheme. For dual fans I like the 3-relay series/parallel wiring and 2 levels of temperature switch. For AC, there is a pressure switch that can turn the fans on when the AC needs the fans.



This is false once you count the rpm range the engine operates in. It's rather difficult to make a mechanical fan operate efficiently over the whole rpm range an engine operates in. An electric fan can be optimized to move the proper amount of air at it's fixed operating speed.

The fan in my 65 Impala draws about 20A. At 14V this is 280W. Even assuming a terrible 50% efficiency for the alternator and belt drive this is a 560W or 0.75hp load when it is running. When it is not running it a 0hp load. It cycles on and off at around a 50% duty cycle even when I'm stuck in traffic on a hot day. I highly doubt any mechanical fan could beat that for efficiency.

74modified

I use both on - different vehicles. There a pros & cons for both.
On my 74 I am using a two speed single electric.
My take on electric:
First you need an electrical system that can handle the load.
I don’t like cheap aftermarket fans. I like OEM fans, but have never used a high quality aftermarket fan - I am too cheap.
You still need to have some sort of shroud to force the air to come through the rad.
I like that with an electric, I can have full airflow at low speed, regardless of engine RPM.

cv67

Only drawback to an electric is if theres a failure youre stuck, mech fans rarely if every fail
Stock clutch fans work well but not a fan of the weight off the water pump nose.
If it were me id get a nylon flex fan (they are black weigh a few ozs arent real noisy and are cheap-call Summit), if you want get an aux electric that would come on at xxx temp maybe even with a manual switch?! (prob not needed though)

You may need a short spacer, some bolts....ran those on my cars for yrs and loved them. Never broke and kept it cool. When I get the time Im putting mine back on with the electric as an aux for the track to cool down in between runs. Do not like the constant temp cycling the electric fans bring on

Wouldnt come anywhere near one of those metal flex fans had a few of those go bad....one cracked my hood, the other broke loose a blade at idle when I had my head under the hood, real close call. Heard a racket and a big bang couldnt see anything happened so fast.

diehrd

For anyone to say a fan does not pull HP out of a motor please rethink that. It is quite a bit of work to push those blades through the air. If I remember right from things I have read it is about 12hp .

Now that is not a lot of hp but for many reasons be it economical hp gains or a racer looking for every spare pony it is a good idea to go electric

AirBusPilot

There is a reason why nearly OEM has switched to electric fans.

AirBusPilot

True. And electric fans don't usually turn on until the engine reaches a temp above normal operating temp. So there is zero drag until that point, unlike even a disengaged mechanical fan.