clutch fan vs standard fan

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gotdust57@yahoo

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what are the benefits of having a clutch fan compared to standard fan and how do they work? thanks
 
Just in my opinion

Standard Fan
-Pros over Clutch - Nothing much, cheaper maybe.
-Cons over Clutch - Direct drive from the engine. From idle to 6000rpm. More load on the engine = robs more power.

Clutch
-Pros over Std - Fan drive is varied by engine temp (cooler the temps, more the fan 'free wheels'. Hotter it tightens up). Given the clutch it will slip and allow the engine the rev 'faster' in most cases.
-Cons over std - ....Cost?
 
There are two types of clutches, thermal like Mike mentioned and non-thermal. The thermal fan speed is temperature driven and the non-thermal is engine speed driven.


Chuck
 
MoPar allways said there viscous fan was 15 HP over a standard car clutch fan. The iceing on the cake was when it was dyno tested just to see if they were right (Telling the truth?) and it did just what they said it would.

The Mopar Muscle mag had the test done and I think writin by Steve D.
 
i like flex fans myself. clutches go bad or blow a bearing and sends the fan through the radiator.

flex fan will suck air when you slow down by grabbing more and be less resistant at higher RPMs... ish.
 
Flex fans also can zing a blade through the hood. Motor mount could go and a fixed fan could eat the shroud and then some. Something can always happen on a failure. Water pump can go with any fan and toss a fan through the radiator. I personally wouldn't run a flex fan if i planned on being under the hood with the engine running at all. Just my 2cents.
 
what about electric fans? are you just wasting time and money with them or will they do the trick? no robbing HP there.
 
In the mag test, the flex fan did the worsed out of all of them.
 
mopar_1974 said:
what about electric fans? are you just wasting time and money with them or will they do the trick? no robbing HP there.
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:toothy7: Not sure if the spacing would work on an a-body. mine works fine.
fan.jpg


fan.jpg
 
Never ever use a flex fan if you tow or drive in mountainous terrain. At high RPM the fan blades flatten out moving less air (for the same amount of drag). So think about what happens if you have to climb a long grade in 2nd gear. Not so freaking good. Electrics are the way to go. Thats why new cars have them (aside from transverse engines). They only draw current when the thermostat demands flow. However, when they are on the alternator load on the engine is close to that of any other fan. Electrics are much better if they are mounted behind the radiator as a puller than a pusher (as a pusher the restriction to airflow is always there fan running or not.)

Also, I have driven cars without engine fans for extended periods of time. I take my truck's fan off for highway trips and it saves about 1 mpg (10% improvement) and a lot of noise. My TR-6 hasn't had a fan in 5 years. Unless you spend a lot of time idling, the fan is just along for the ride.
 
I use sort of a compromise to the "no-fan-at-all" approach on my Duster with a very small all-plastic flex fan. I doubt if it weighs more than 10oz., so drag is minimal. With a bit over two inches from the blade tips to the shroud, it pulls just enough air at idle to smooth out the temp spike to prevent overheating if I get stopped in traffic on a hot day. It couldn't possibly do much damage if it ever came apart (doubtful) - it is one solid piece of platic or polymer composite of some sort.
 
Good point Chief. Goody has a great set up there. On my Duster, I did a perma cool electric fan.
 
DragginMAster said:
i like flex fans myself. clutches go bad or blow a bearing and sends the fan through the radiator.

flex fan will suck air when you slow down by grabbing more and be less resistant at higher RPMs... ish.
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FWIW, a clutch fans does not have any clutches. It's more kin to a torque convertor. There is a viscous fluid in side that couples inner driven impeller to the outer housing the fan is attached to. The non-thermostatic ones have a constant slip rate. The thermostatic ones vary the slip rate with temperature, i.e. higher temperature less slip.

The typical failure mechanism is the seal will fail and the fluid will leak out and the slip rate will increase until it can't keep the engine form over heating.

I had one that the bearing failed on and it allowed the fan to wobble which created some vibration and also essentially locked up so there was almost no slippage. But, there was no danger of the blades seperating and in my case it was far enough away from the radiator there was no danger of the blades hitting the radiator.

The flex fans have a much much higher incidence of failure where a blade seperates from the hub.
 
DragginMAster said:
my brother had a clutch fan fail and destroy the radiator in his charger.

shite happens as they say.
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No reason to toss that idea out. my 2005 truck has a clutch fan, so they aren't obsolete. Any fan can go. .02
 
My friend had a flex fan blow apart and take out his hood. Also flexs fans are rated for no more then 6500rpms. Cant use one on my 340 because of it and probably wouldnt if I could.
 
That rpm that Adam is talking about is fan speed not crank speed. There are a lot of engines that the water pump pulley is smaller than the crank so it is very easy to overspeed the fan. Flex fan = run, run very far way.

Chuck
 
C130 Chief said:
Never ever use a flex fan if you tow or drive in mountainous terrain. At high RPM the fan blades flatten out moving less air (for the same amount of drag). So think about what happens if you have to climb a long grade in 2nd gear. Not so freaking good. Electrics are the way to go. Thats why new cars have them (aside from transverse engines). They only draw current when the thermostat demands flow. However, when they are on the alternator load on the engine is close to that of any other fan. Electrics are much better if they are mounted behind the radiator as a puller than a pusher (as a pusher the restriction to airflow is always there fan running or not.)

Also, I have driven cars without engine fans for extended periods of time. I take my truck's fan off for highway trips and it saves about 1 mpg (10% improvement) and a lot of noise. My TR-6 hasn't had a fan in 5 years. Unless you spend a lot of time idling, the fan is just along for the ride.
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Another old biker i know was working out at St Augustine we lived in Middleburg. Fan came apart on his Ford blew up ihs radiator brought him a rad and told him to drive home without a fan it was winter time and we had no overheating issues because I told him keep that truck moving. I was in my vehicle following all the way home
 
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Ironracer said:
Another old biker or not we're working out at St Augustine we lived in Middleburg. Fan came apart on his Ford blew up ihs radiator brought him a rad and told him to drive home without a fan it was winter time and we had no overheating issues because I told him that truck moving. I was in my vehicle following all the way home
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I TESTED FANS ON MY CAR ALL LAST SUMMER , FLEX, ELEC. CLUTCH TYPE , FIXED FACTORY , ALL WITH A SHROUD , ALL IN A SMALL 68 BARRACUDA ENGINE BAY , W/ A 440/505 WEDGE .WHICH IS FAIRLY HOT , SUPPOSEDLY 761 H.P. , BUT HASNT RUN LIKE IT SO FAR.
I tried 4 dif. elec. fan set ups , but not a contour type , big joke in my case . FIXED 7 BLADE FACTORY COOLED THE BEST , BUT SETTLED ON A 7 BLADE CLUTCH TYPE , THE FIXED FAN WAS ABOUT 7-8 DEGREES BETTER , THAN ANY , BUT ACCORDING TO AN "ENGINE MASTERS" TEST , COST ABOUT 20 H.P------------JFYI
 
340mopar said:
That rpm that Adam is talking about is fan speed not crank speed. There are a lot of engines that the water pump pulley is smaller than the crank so it is very easy to overspeed the fan. Flex fan = run, run very far way.

Chuck
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So I should shelf the flex fan on my 340? I knew they were an outdated design and I figured the clutch fan was the way to go I had no idea they blow up and screw your **** up
 
For a typical sub 450hp streeter
the thermostatic clutch on an all steel 7-blade fan will do a great job. You might never even know it's there.
My 195 hi-flo coolant thermostat keeps the minimum water temp at about 205*F, and the clutch together with the hi-flo pump never lets it get past about 207*F, what a team.
This fan works hard in traffic but once past about 35 mph, ram-air thru the rad decouples it, and it freewheels. So at rpm, in Second-Over/ 93 mph it is just along for the ride. On the return road, while the Alloy heads are aircooling, I hear the clutch start-up again. But the gauge hardly moves.

See; that is the One aspect the Dyno never tells you. Once the engine is installed in a moving car, all those dyno-test results go right out the window. Well except the direct drive one, but I don't know anyone who would, other than for testing, run a direct drive fan. I mean imagine the tip speed at 7200,lol. That's crazy.
 
Used to take the fan off of my old ford in the winter time. I could defiantly feel the difference. In line 240
 
Fans are designed based on application. That means what you are going to do with your car. Race it 1/4 mile a ta a time ? Don't need much of a fan.
Real life driving...idling sometimes, around town sometimes, hi-way some times. You need an all around setup. Low speeds under 45, Clutch/thermal type. Just like the factory designed ( for good reasons). Over 45 mph, fan does little to nothing, more air is forced thru the radiator because of vehicles speed.
Plastic/flex type fans, did any manufacturer ever install them on passenger cars ?? They are always blamed for putting the cheapest thing they can get to save money. What do you think.
Anything man made can fail but the scales tilt way to factory set up. For every story about I know somebody ( always someone elses) who had a clutch fan fail you can multiply times 1000 how many times a flex fan failed or someone got hurt while under the hood revving hid engine and a piece/blade came off.
Electric fans make the most sense now a days but were originally used because a transverse mounted engine has a problem mounting a fan on the side of the engine. and doing any good.
 
MoparLeo said:
Fans are designed based on application. That means what you are going to do with your car. Race it 1/4 mile a ta a time ? Don't need much of a fan.
Real life driving...idling sometimes, around town sometimes, hi-way some times. You need an all around setup. Low speeds under 45, Clutch/thermal type. Just like the factory designed ( for good reasons). Over 45 mph, fan does little to nothing, more air is forced thru the radiator because of vehicles speed.
Plastic/flex type fans, did any manufacturer ever install them on passenger cars ?? They are always blamed for putting the cheapest thing they can get to save money. What do you think.
Anything man made can fail but the scales tilt way to factory set up. For every story about I know somebody ( always someone elses) who had a clutch fan fail you can multiply times 1000 how many times a flex fan failed or someone got hurt while under the hood revving hid engine and a piece/blade came off.
Electric fans make the most sense now a days but were originally used because a transverse mounted engine has a problem mounting a fan on the side of the engine. and doing any good.
Click to expand...
Surprised they didnt make a 180 degree fan for those transverse engines... wait for it...
 
4 guys leaning under hood of a Chevy with a four blade stock fan. One was revving the engine quite high, one blade came off and cut one guys head almost off, he died. I raced 8 years with a fiberglass fan on my Max Wedge turning 6800 rpm, never broke. I’ve had flexible metal, stock metal, clutch type, you name it, since 1967 and NEVER broke a single one. Chrysler made a viscous drive unit to use on the crank so the fan, water pump and alt would reduce pull on engine. That was when you had to run the factory setup in class racing
 
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