Replace old flex fan with what?
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
I have fought with heat issues in the summer here in Upatste New York. We get 90 plus heat with 100% humidity mid summer. I fought with seals, shrouds, wetter water, by passing, timing, the hole deal. Everything the forum said... Still, a 30 minute blast at 70 down 390 put the old girl on the critical list>>> Up until I took all that plastic stuff off and put a modern fan on it.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
I have fought with heat issues in the summer here in Upatste New York. We get 90 plus heat with 100% humidity mid summer. I fought with seals, shrouds, wetter water, by passing, timing, the hole deal. Everything the forum said... Still, a 30 minute blast at 70 down 390 put the old girl on the critical list>>> Up until I took all that plastic stuff off and put a modern fan on it.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I guess that I am one of the few Nay Sayers to stock clutch fans.
Lower rpm motors they might be fine. Higher rpm powerful motors need cooling at higher rpm not a fan free wheeling. I used the light weight 10,000 rpm rated stainless steel flex fans for many years. I sanded the edges so you would not get cut.
Stock heavy clutch fans are not made for over 6000 rpm motors
When you need lots of cfm of air pulling through the shroud the 10,000 rpm fans are the best mechanicals made.
I'm also pro aluminum high flow water pumps and the tall filler and cap on the intake with the cooling lines from the back of the manifolds
Lower rpm motors they might be fine. Higher rpm powerful motors need cooling at higher rpm not a fan free wheeling. I used the light weight 10,000 rpm rated stainless steel flex fans for many years. I sanded the edges so you would not get cut.
Stock heavy clutch fans are not made for over 6000 rpm motors
When you need lots of cfm of air pulling through the shroud the 10,000 rpm fans are the best mechanicals made.
I'm also pro aluminum high flow water pumps and the tall filler and cap on the intake with the cooling lines from the back of the manifolds
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
Nothing on my Silver Anni has ever spun that fast! 
I always fill the rad and then back fill the upper rad hose. They can also be shortened about 3 inches, that smothes out the bends and lets water move a little better.
I always fill the rad and then back fill the upper rad hose. They can also be shortened about 3 inches, that smothes out the bends and lets water move a little better.
Last edited by ThePabst; Apr 27, 2012 at 08:47 AM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You also have to figure in the pulley ratio. like a 6 inch crank pulley and a 4 inch water pump would be 33% overdriven fan
So at 6000 rpm your fan blades are doing 9000 rpm. right about where the stock fan clutch is ready to launch the blades through the hood. the 10,000 rpm models are actualy tested to 14,000 rpm ofr some number like that
So at 6000 rpm your fan blades are doing 9000 rpm. right about where the stock fan clutch is ready to launch the blades through the hood. the 10,000 rpm models are actualy tested to 14,000 rpm ofr some number like that
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Thread Starter
Racer
Joined: Apr 2002
Posts: 345
Likes: 0
From: ny
These use a ton less power than the old steel flex fans do are quieter and dont come apart. Only weigh a few oz and you wont have extra weight hanging off the WP.
Like others have had..had a steel blade come off at idle while I was under the hood, another came apart sitting in the car revving it. That could kill ya
Probably stick one of these back on this summer and keep the electric as a fail safe "just in case". Have 2 they are super old..cause they dont break lol.
http://www.summitracing.com/search/?...on%20fan&dds=1
know a lot of imports used a clutch fan with those white nylon type fans too bad GM doesnt have something like that. Seems like a perfect compromise.
Like others have had..had a steel blade come off at idle while I was under the hood, another came apart sitting in the car revving it. That could kill ya
Probably stick one of these back on this summer and keep the electric as a fail safe "just in case". Have 2 they are super old..cause they dont break lol.
http://www.summitracing.com/search/?...on%20fan&dds=1
know a lot of imports used a clutch fan with those white nylon type fans too bad GM doesnt have something like that. Seems like a perfect compromise.
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
You also have to figure in the pulley ratio. like a 6 inch crank pulley and a 4 inch water pump would be 33% overdriven fan
So at 6000 rpm your fan blades are doing 9000 rpm. right about where the stock fan clutch is ready to launch the blades through the hood. the 10,000 rpm models are actualy tested to 14,000 rpm ofr some number like that
So at 6000 rpm your fan blades are doing 9000 rpm. right about where the stock fan clutch is ready to launch the blades through the hood. the 10,000 rpm models are actualy tested to 14,000 rpm ofr some number like that
I wondered when somebody would mention that.......... 
