Flex it baby!!!!!

[vanderkwv]

I have a stock 72 318 Duster and I though I'd be cool and remove the viscous clutch and steel fan. In doing so I bought a nice stainless steel flex fan and installed it with a 1 3/4" spacer between the pully and fan so it'd be well inside the fan shroud.

Well, now that it's in, that thing is loud . What a roar! I'm not sure I like it.

Anyone else go down this path? Maybe if I re-install a viscous clutch, a newer later model, again things'll quiet down?

Can I run a flex fan with a clutch?

Do all flex fans make this much noise?

And there's temperature sensitve clutches ahhhh .....what do I do?

[George G. Leverette]

The first thing to do is get a spacer that positions the fan half in, half out of the shroud. You are substuting an inferior fan system for one with less capicity to cool, is always engaged and the noise factor has already been experienced. If changing the spacerdosent work for you, put the original fan and clutch back on the car.

[vanderkwv]

So you're saying just moving the fan forward or backward can alter how much noise it's making? It seems to correctly positioned already.

And you think this fan cannot cool as well as the stock one?

[dwc43]

If it's inside the shroud it's not correct. About a 1/2 inch or so should stick out from the shroud. If it's inside it can actually stall the air flow and it can over heat that way.

The flex fans are fine. They pull lots of air all the time where the clutch type kicks out when hot and at speed. We run a plastic flex fan on our race cars. Works great and it's lighter than all others too. By the way some mopars come stock with flex fans for years and work just fine.

[vanderkwv]

But what about the noise? It's way too loud for me.

I noticed in the PAW catalog that mopar performance has a light weight fan and a viscous clutch setup for about $114, I wonder if that's a good way to go?

[dwc43]

Noise gets louder with increase of blades or blade pitch. I went from 5 to seven on a truck and it sounds like a helicopter and it has a visous clutch drive on it. So the drive wont help you any. Try that plastic 5 blade plastic flex fan form Summit Racing. It's not loud and it cools the race car real well. 190 most any night it runs.

[vanderkwv]

Why did you combine the clutch and the flex fan and not run the flex fan all by itself?

I'll have to say the weight of my stock clutch and fan was much more than the flex fan I just put on.

[dwc43]

You read the post wrong my friend. I put the clutch fan on the truck. It had a 5 blade clutch fan and I put a 7 blade clutch fan on it. My race cars use the 5 blade plastic flex fan from flex a lite with no clutch at all.

[George G. Leverette]

One of the best places to pick up a fan is the junk yards, the 5 and 7 blade fans are plentiful, Auto zone and others sell the fan clutch make sure you get the premium setup. Oh yes the fans come in 20" and 18" sizes get one that fits.

[vanderkwv]

Are you suggesting I return to a clutch type fan or do you suggest I continue with a flex fan only?

All I'm looking for is something more efficient than the heavy setup I had with stock components. But something that can still provide the flow for proper cooling.

AND something that doesn't sound like a hurricane!

Maybe I can follow dwc43's suggestion and try a 5 blade fan ( I have 6 ) and no clutch, I don't know.......I'm so confused....

[Warlock_440]

OR... you could ditch the engine driven setup and go with a nice electric fan. No parasitic power loss and theyre pretty quiet too.

Just my thoughts.

[dwc43]

Originally posted by vanderkwv
Are you suggesting I return to a clutch type fan or do you suggest I continue with a flex fan only?

All I'm looking for is something more efficient than the heavy setup I had with stock components. But something that can still provide the flow for proper cooling.

AND something that doesn't sound like a hurricane!

Maybe I can follow dwc43's suggestion and try a 5 blade fan ( I have 6 ) and no clutch, I don't know.......I'm so confused....

I'd try the plastic flex a lite 5 blade flex fan. That should be a little quieter. Just remember it's the fan that makes the noise not the clutch. Number of blades and fan blade pitch angle is what makes the noise. And like warlock said, the electric ones are nice and quiet too. And still no power loss from them. And you can get them at the junk yard real cheap. Try to find a newer model police car and get the electric fan from it. It will work best.

[fastmopars .inc]

hahhahaah
you run the plastic flex fan on your RACE CARS?
whats wrong with you?

okay, here goes.

dyno time, 440, 906 heads, 10.8 compression 509 cam, team g, 830 holley, 532 hp baseline (no fan)
hp with plastic flex fan = 480. 52 hp less! at 6200 rpm! how fast are you spinning those race engines? those plastic fans are the worst kind you could buy, on my stock 318 dart removing the plastic fan and going with a factory clutch fan was worth 4 tenths of a second.
stock 7 blade 17 inch fan = 508 hp. only 25 hp loss. and cheaper.
clutch fan, 5 blade, 17 inch = 525 hp. only a 8 horsepower loss.
32 amp draw on alternator to simulate dual 10 inch electric fan set up = 520 hp. less than 15 hp. probably less if charging system is up to par, i have an older alternator.

most people know that the clutch fan is the best way to save horsepower with the fan. the second best way to do it would be run electric fans, but cut out the alternator during your pass so the load from the fans does not affect the charging field on the alternator. i have seen that same plastic flex fan hog 60 hp at 6500 rpm off a small block chevy. STAY AWAY from the cheapo plastic fan.

there are vacuum operated switches that could be used to shut off your alternator field at wot (zero vacuum) which is what i use on my satellite. alternator off for the pass (on while burnout and staging) is worth usually almost a tenth of a second.

electric fans are best, i would use a clutch fan if already so equipped.

if having cooling problems, the plastic fan is the one to use. this fan moves more air than any other fan i have ever seen. ever. when i had this on my 318 dart at high idle in the mornings i could stick a hat or touque to my grille.
makes sense that it would create such a large loss.

[dwc43]

One, nascar rules say i have to have an engine driven fan. Two, they move plenty of air but cost no horse power. The weigh only a few ounces and any one knows that reduced rotating mass reduces engine acceleration times. My dyno says different. Plus the added weight of the clutch hurts it too. That's why we run them. Look under a chebby hood at the track and I find steel 4 blade flexs on theres. I'm at a slight advantage to them.

[jasontlit]

Aside from all these posts with some very good advice...

You're talking about a stock small block Duster that sounds like a driver.

Why are you so concerned with trimming a bit of weight there?
The clutch fan is a great system for a basic ride.

You aren't going to see any real positive measurable results in a driver from messing with the fan.

[jasontlit]

Oh...My last post was meant for vanderkwv...not dwc43 who is in a completely different situation.

[dartswinger74]

I dont mean to ask a dumb question but are you sure the fan is on correctly? I saw a guy bolt one on a 318 in a pickup backwards once. That made a lot of noise!! My 360 has the flex fan that was stock on the 318 and it is only noisey when the hood is open and you rev it. My exhaust isnt all thet loud so I should hear it. All I hear is that big bore TQ trying to suck the hood through the secondaries.

[vanderkwv]

jasontilit, your point is well taken. But I enjoy the dialog here, there's lots to learn, and this is what makes moparchat so great.

This is a daily driver and yes it's only a mild 318. But I'm trying to think ahead. See I have plans for a 400HP 360 at some point so I wanted to make a change that would be suitable for future use.

My first thought was an electric fan, and I've installed one on my (I shouldn't say this) 5.0 mustang , it's the black magic from flex-a-lite, and it works great. But can a electric fan handle a 400HP engine? I've noticed some actually have a HP rating. So....thinking they could not, I opt'd for an flex.

See where I'm going here? Sheesh, if a clutch and a plastic fan is the way to go then I go that route, but if an electric can hangle my future needs, I'll do that.....

[jasontlit]

I agree with you on enjoying the dialog.

I may be wrong, but the same clutch fan should cool a hopped up SB. Given that it is using coolant/water and has the proper thermostat (around 195).

The horsepower robbing issue is another story. I've always liked the clutch fan for the fact that it was designed to spin more slowly at higher rpm to minimize HP loss, than if it was attached in a static fashion to the H2O pump.

The idea being that at, say, 50 mph and above there is enough airflow to cool the engine without a fan at all. That was something I've read in an esteemed Mopar mag anyway.

Plus, run a tranny cooler to aid in not taxing the radiator. My 340 runs at 195 degrees on the nose regardless of weather or driving conditions.

[fastmopars .inc]

dwc43
sorry about the rudeness of my last post, i should have worded it differently.
i also thought that the reduced rotating mass would make a difference, as they are indeed only 11 ounces.
i actually have 3 in my garage, because i bought one for all my cars when they were on sale for 13 bucks.

as well, they are called a flex fan, so that insane almost 90 degree pitch on the blades should flex flat, right? well, i have buzzed my motor to 6000 while watching the fan those blades don't really change pitch that much. they just kind of arc backwards because of all the air that they are blowing!

the best example i have of this was that in my 69 dart with a 69 318 and headers and a carter on a 340 intake, ran 15.8 with this fan on, and with the fan off it picked up 3 mph and went 15.4@89
thats a pretty big difference for a car that only pulled to 4800 rpm



i have a 360 thats pushing probably 400-450 hp. runs mid 12's in a totally complete show car. stock v8 rad, stock 15 inch clutch fan and fan shroud and 160 degree high flow thermostat from mr gasket. my track does not allow ethylene glycol in the cars so i run a mix of water, rust protector and watter wetter. this is my daily driver and in rush hour traffic 30 degrees celsius it rarely goes above 180, and will sit at 160 at speed.

electric fans from 3.8L ford v6's are the ones to get, either dual 10 inch (24 inches across total) or dual 12 inch (26 inches across total, yes, i measured correctly) the smaller of the two should fit most a-body rads. i got them for 20 bucks each at the wrecking yard, and the smaller one cools my 550 horse 440 in traffic and at the strip. once the fans are on, the motor will not go above the thermostat opening point.