Flex Fan
 

Does the flex fan work that much better or does it just look cool? I am about to order one for the car and don't know what kind or what..What do you all think?

http://www.jcwhitney.com/flexalite-u...=c1647d397u0j1

Ray -

There are been a number or "studies" on this.

The clutch fan is reported to cool better than the flex fan, and in theory have less parasitic HP loss. (Neither were true in my case.)

The electric fans adequately cool and shouldn't have any parasitic drag on the motor. (Until you realize where the electricity powering the fan is coming from...) Also one more electrical thing to go wrong.

A properly sized flex fan that has been set up correctly (position matters) can move mountains of air through the radiator, is virtually fool proof (size and placement taken), but can cost you 10 - 15 HP in parasitic drag. It also gives you the most bang for the buck on a street car. Yeah, they do look cool.

I believe mine is 19" and has 7 blades - kinds sounds like a blower ;)

Archer

The other thing about electric fans is the motor also blocks some of the radiator....Or am I just to critical...But you are right when the fans come on you can hear the Rpm drop...Just saying ...Bill:)

I ran a nice electric fan on my fury and I felt the power gain ‘seat of the pants’ style. It really freed up some power but yea, it takes some juice from the alternator. I’m not a huge fan of flex fans but I don’t race, just cruise my stuff.

I wouldn't bother, go with a clutch fan setup as suggested above. The flex fan people say you'll make power with their fan because the blades flatten out at high rpm, right? What do you think is flattening them? Air resistance, and you're still fighting it when it's flattened out, that's why it stays flat. The clutch disengages all together at high rpm. Win.

Flex Fans scare me they flex back and forth and back in the day people were getting killed by them coming apart bldes breaking and even coming through the hood...Bill

Mr 4 speed -

Which clutch fan(s) disengage at high rpm?
The only ones I know about are "thermo-viscus" fans and the "clutch" engages as the temperature rises, regardless of the rpm. I'm sure there are newer models that can accept multiple inputs, but the standard Mopar clutch fans just work by heat.

At low rpm, the extra blade surface of most flex fans should move more air than the usual configuration of most clutch fans, whether the latter las locked up or not.

Bill -

Anything in a car can kill you if it fails at the wrong. Fact is that over the years, there have been more flex fans in use on hot rods than probably any other type. These days, most flex fans have rpm ratings. If you stay within those ratings, danger from it is pretty low on my "worry about" list.

Side note: the flexing of the blades actually adds a measure of insurance against breakage than a more rigid structure. Both versions try to flex under increase rpm (air pressure) one can and one can't.

Now, it I were building a 10 sec track car, a flex fan might not be my first choice. For the street in a 6,500 red-line motor, it makes a little more sense.

Archer

Good catch, Archer. I was certain they disengaged at a set rpm (something I apparently mis-read years ago) , after seeing your post I researched it and I'm wrong. They do slip at at high rpms, though I'm not sure how much.

I would say good catch as well But I do not know any better..... that's why I ask you guys...LOL

The sound a flex fan makes is awful plus you cut the crap out of your hands working around them. I have threw a pile of them in the trash can. Buy a mopar viscous fan, good enough to cool a hemi back in the day.


http://www.summitracing.com/parts/dc...FWvxOgodYAwAPA


Most late 1960s and early 1970s factory-built musclecars were equipped with viscous fans for cooling purposes. Engineers determined through dyno testing that you could gain up to 15 extra horsepower with typical high-performance V8s. These viscous fan packages from Mopar provide thermostatically controlled cooling. They feature a lightweight, balanced fan that uses the least amount of horsepower necessary to turn

So my question is how does a fan make HP? Sorry for the stupid question.

I think the flex fans making horses is largely a myth (esp when you aren't making 500 or more horses to start with). As has been very correctly pointed out in this thread, they still fight against air even when flat. Their natural state or position is curved, so they are constantly trying to get back that way. oh, it might save a little bit of power, but I wouldn’t think enough to be worth it. Your best bet is to go electric or clutch with a good shroud, in my opinion.

Archer, let me varify what I was talking about back in the day mid 70s Ford had a huge law suit and Recall on all there fan blades...I guess a tech or techs ( they were called mechanics back then) were unber the hood of a car revving the engine up and the fan came apart and killed him..Im sure it wasn't pretty for the other guys to see...But I remember the recall well I must of change 1000 fan blades if I change 1... Dont get me wrong the new flex fans like you say are speed rated and if you stay in that range you will be ok...The problem is I was looking at a fan a couple of mounth ago at a discount auto store..(Advance Auto) and the blade said DO NOT exceed 4000 RPMs That in the wrong hands could be a recipe for disaster...:yikes:....Bill

ray -

Fans (any fans) don't "make" HP. They can however, "save" or increase the amount of HP going to the rear wheels.

The HP from an engine not only has to drive the rear wheels, but any accessories on the engine, like the water pump, alternator, A/C and yes the fan. The HP is used up by the fan pulling (or pushing) mountains of air though the radiator, never gets to the rear wheels.

Bill -

Sounds like a defective part or lot. As awful as it was, you can't condemn the entire theory because of one poor product. (I know you weren't trying to do that.) The first thing I look at with any moving part is intended use/rpm range. It has be to well above anything the engine is going to produce.

Purple -

Yes, most cars came with some type of viscous fan in the 70's, (oddly enough, a number of hemis didn't), and it was one of the first things most hot rodders threw out.

Cooling efficiency is a combination of cooling surfaces and air flow. The cooling surface is the size and design of the radiator; the air flow is a combination of the fan cfm, vehicle speed/access to incoming air. The only complication is that the more air the fan moves, the more power is required.

Look, each type of fan or anything else, has it's place, and that's up to the user to figure out which is going to work best for his application. The fact is that viscous fans, flex fans and electric fans have been around longer than most of us have.

Archer