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clutch fan vs a flex fan HP difference? #1327521
10/28/12 08:21 PM 10/28/12 08:21 PM
Joined: Oct 2003
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South Park, Pa.
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This has been discussed in the past, I'm sure. What is the HP loss between the 2 fans, clutch vs stainless flex fan, for a street strip engine? I got into a discussion with a friend of mine the other day. He says that a clutch fan is heavier and will not spin free at RPM, causing a loss of HP. He also says that a SS flex fan is lighter and will flatten out a rpm, thus freeing up more HP than the clutch fan.
My engine runs better with a clutch fan, and it also runs cooler. How about you guys?

4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
Re: clutch fan vs aa flex fan HP difference? [Re: 68LAR] #1327522
10/29/12 08:17 AM 10/29/12 08:17 AM
Joined: Jan 2003
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Niles , Ohio
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therocks Offline
oh wait.but hey.lets see.oh yeah.
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I dont know about HP loss.I run a big SS flex on my 65 440.It has an untouched 65 rad and runs under 190 all day even when its in the 90s.Its been on for at least 15 years.I also ran one on my Jeep plow truck.It was a smaller one.It ran cool even at highway speeds with the plow on at highway speeds.I probally put 80K on that one.Rocky

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Re: clutch fan vs aa flex fan HP difference? [Re: therocks] #1327523
10/29/12 09:05 PM 10/29/12 09:05 PM
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oklahoma
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forphorty Offline
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Re: clutch fan vs a flex fan HP difference? [Re: 68LAR] #1327524
10/30/12 11:16 AM 10/30/12 11:16 AM
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Az
Crizila Offline
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I've tried both, and the flex fan was worth about 2 tenths on my car.

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Re: clutch fan vs a flex fan HP difference? [Re: Crizila] #1327525
10/30/12 11:25 AM 10/30/12 11:25 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
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Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.



what? something else must have been going on to pick up 2 tenths...
I'll say no difference except cut up fingers while working around it and a shreaded fan and or hood when it decides to let go. I run the plastic 18.5" summit fans, they work great, are very very light and cheap.

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Re: clutch fan vs aa flex fan HP difference? [Re: forphorty] #1327526
10/30/12 11:36 AM 10/30/12 11:36 AM
Joined: Oct 2003
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South Park, Pa.
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Unless I'm reading something wrong, those articles are stating that the clutch fan, cools the best and draws the least amount of horsepower.
Having tried both, myself, I found that both cooled the same and the question I had was with HP lose, due to the difference in weight and the flattening of the fan blades at rpm. I've been using the clutch fan for several years now with no issues.

4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
Re: clutch fan vs aa flex fan HP difference? [Re: 68LAR] #1327527
10/30/12 12:32 PM 10/30/12 12:32 PM
Joined: Dec 2005
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State of Fascism
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52savoy Offline
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Sport Truck magazine did a dyno test about 11 years ago. They used a fixed fan, flex fan, clutch fan,..no fan at all! and an electric fan.

I don't remember the exact figures, but the electric and the "no fan" set up picked up the same and best hp(16?). I believe the flex and fixed had the most drain on hp.

Looks like the Car Craft test pretty much mirrored the Sport Truck test.

Sport Truck might be on the net somewhere

Last edited by 52savoy; 10/30/12 12:42 PM.
Re: clutch fan vs a flex fan HP difference? [Re: Crizila] #1327528
10/30/12 12:37 PM 10/30/12 12:37 PM
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State of confusion
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Thumperdart Offline
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Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.

That`s roughly 40-50 hp I would think............ I love my elec. fan..................

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Re: clutch fan vs a flex fan HP difference? [Re: Thumperdart] #1327529
10/30/12 02:28 PM 10/30/12 02:28 PM
Joined: Oct 2003
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South Park, Pa.
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Quote:

I love my elec. fan..................


I've tried electric in the past with no luck. The car over heated constantly. Actually, I know many friends that use electric fans on old muscle cars that are dual duty, street and race. They also have over heating problems. Granted, there is a HP gain to be had, but having a street car, adequate cooling also has to be considered.

4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
Re: clutch fan vs a flex fan HP difference? [Re: 68LAR] #1327530
10/30/12 08:25 PM 10/30/12 08:25 PM
Joined: Jan 2003
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Balt. Md
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383man Offline
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I had considered the electric water pump before but I just was not convinced it would cool it good enough on the street which is where I drive the most. So I stuck with the stock type waterpump with the good old belt driven. I am sure I could pick up a few hp but I dont think it is worth it for me. I do use a flex fan and have added an electric fan pusher on the outside of the rad as if I sit in real hot traffic for about 1/2 hr it gets up to 200 and I can flip the toggle switch and turn the electric fan on to cool it down some. The clutch fan works good when working right as it should lose most drag on a cool eng but if you eng is hot up near 190 to 200 it can be fully engauged and rob hp at a stop after you get moving and get alot of air going thru the rad it will disengauge until you stop and the eng temp goes up a little again. So if you are idleing for a few minutes with a clutch fan and the eng is hot it should be fully engauged and hurt hp when you launch and it may not start to disengauge until the end of the 1/4 mile.. I guess I would try to race with my eng at about 160 at the most with the clutch fan. Ron

Last edited by 383man; 10/30/12 08:30 PM.
Re: clutch fan vs a flex fan HP difference? [Re: 68LAR] #1327531
10/30/12 08:57 PM 10/30/12 08:57 PM
Joined: Oct 2003
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Az
Crizila Offline
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Quote:

Quote:

I love my elec. fan..................


I've tried electric in the past with no luck. The car over heated constantly. Actually, I know many friends that use electric fans on old muscle cars that are dual duty, street and race. They also have over heating problems. Granted, there is a HP gain to be had, but having a street car, adequate cooling also has to be considered.

Thats the problem I had also. I race in some pretty hot weather and the elerctric fans I tried weren't maken it. I gave up some ET for no overheat problems. My previous statement of 2 tenths might have beeen a little "happy", but I did see an improvement in ET going from the big HD clutch fan to the 19" flex fan. I also didn't like the inconsistancy of the clutch fan - temp wise.

Fastest 300
Re: clutch fan vs a flex fan HP difference? [Re: Mr.Yuck] #1327532
10/31/12 12:10 AM 10/31/12 12:10 AM
Joined: Apr 2009
Posts: 3,429
Toronto
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mshred Offline
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Quote:

Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.



what? something else must have been going on to pick up 2 tenths...
I'll say no difference except cut up fingers while working around it and a shreaded fan and or hood when it decides to let go. I run the plastic 18.5" summit fans, they work great, are very very light and cheap.



Those summit fans are electric?
Re: clutch fan vs a flex fan HP difference? [Re: mshred] #1327533
10/31/12 09:53 AM 10/31/12 09:53 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:

Quote:

Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.



what? something else must have been going on to pick up 2 tenths...
I'll say no difference except cut up fingers while working around it and a shreaded fan and or hood when it decides to let go. I run the plastic 18.5" summit fans, they work great, are very very light and cheap.



Those summit fans are electric?



http://www.summitracing.com/parts/sum-g4948/overview/ I've used 3, none of the engines including this one will go above 190, most of the time it will stay under or at 180*. You will need a spacer, I think 1.5" on my Charger.
Re: clutch fan vs a flex fan HP difference? [Re: Mr.Yuck] #1327534
10/31/12 10:02 AM 10/31/12 10:02 AM
Joined: Apr 2009
Posts: 3,429
Toronto
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mshred Offline
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Quote:

Quote:

Quote:

Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.



what? something else must have been going on to pick up 2 tenths...
I'll say no difference except cut up fingers while working around it and a shreaded fan and or hood when it decides to let go. I run the plastic 18.5" summit fans, they work great, are very very light and cheap.



Those summit fans are electric?



http://www.summitracing.com/parts/sum-g4948/overview/ I've used 3, none of the engines including this one will go above 190, most of the time it will stay under or at 180*. You will need a spacer, I think 1.5" on my Charger.



thanks

Re: clutch fan vs a flex fan HP difference? [Re: Mr.Yuck] #1327535
10/31/12 10:07 AM 10/31/12 10:07 AM
Joined: Mar 2010
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Out in Left Field, NY
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bobs66440 Offline
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Out in Left Field, NY
Quote:

Quote:

Quote:

Quote:

I've tried both, and the flex fan was worth about 2 tenths on my car.



what? something else must have been going on to pick up 2 tenths...
I'll say no difference except cut up fingers while working around it and a shreaded fan and or hood when it decides to let go. I run the plastic 18.5" summit fans, they work great, are very very light and cheap.



Those summit fans are electric?



http://www.summitracing.com/parts/sum-g4948/overview/ I've used 3, none of the engines including this one will go above 190, most of the time it will stay under or at 180*. You will need a spacer, I think 1.5" on my Charger.

I'm using the same fan. Works very well and ridiculously light.

Re: clutch fan vs a flex fan HP difference? [Re: bobs66440] #1327536
10/31/12 10:21 AM 10/31/12 10:21 AM
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
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Another friend of mine uses that Summit plastic fan. We were at a cruise the other night. On the way there we hit some heavy traffic. When we finally got there, his engine temp was over 220*. Mine never got above 165*. We both run 160* stats. Like I said, I use a thermal clutch fan. The short one. I think it's for a Jaguar, not sure though. Supposedly, the clutch locks up at 180*. So most, if not all of the time, it is free-wheeling. This system works the best for me, although, the clutch assembly is a little heavier than a steel flex. I, personally would NEVER run a plastic fan. I've seen too many come apart over the years. Same goes for aluminum flex fans.

4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
Re: clutch fan vs a flex fan HP difference? [Re: 68LAR] #1327537
10/31/12 10:45 AM 10/31/12 10:45 AM
Joined: Jan 2003
Posts: 13,417
Marion, South Carolina [><]
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If you get a GOOD electric fan, you won't have any overheating issues.

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