Electric Fan CFM Requirement
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Electric Fan CFM Requirement
It seems that the Mark VIII is the popular fan to swap around here. (Due to its dimensions and CFM I'm assuming.) (4K+ CFM?)
But is that much airflow really necessary? I notice that most of the universal ones in my Jegs and Summit catalogs are rated at 2K-3K CFM. Would something like that work for a 450hp SBC without AC? (Aluminum radiator with a highflow waterpump)
But is that much airflow really necessary? I notice that most of the universal ones in my Jegs and Summit catalogs are rated at 2K-3K CFM. Would something like that work for a 450hp SBC without AC? (Aluminum radiator with a highflow waterpump)
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
It seems that the Mark VIII is the popular fan to swap around here. (Due to its dimensions and CFM I'm assuming.) (4K+ CFM?)
But is that much airflow really necessary? I notice that most of the universal ones in my Jegs and Summit catalogs are rated at 2K-3K CFM. Would something like that work for a 450hp SBC without AC? (Aluminum radiator with a highflow waterpump)
But is that much airflow really necessary? I notice that most of the universal ones in my Jegs and Summit catalogs are rated at 2K-3K CFM. Would something like that work for a 450hp SBC without AC? (Aluminum radiator with a highflow waterpump)
The only downsides to a fan with that much power and pulling force...are noise, and power consumption. If you do upgrade to a MarkVIII fan I would suggest an upgrade to your charging system. A healthy upgrade is to a CS alt, either the 130 or 144. It's an easy swap and will give you plenty of amps.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Why is $70. a magic number?
80 amps at idle? Who idles around in a Vette?
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
I like the CS144, but I wouldn't want to buy one new. $170 for an alternator is
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Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
$70 is half what a new CS144 costs, and anyone that drives in stop and go traffic at all is gonna be at an idle. If the electrical accessories are drawing more than the alt can produce at that idle then you're just draining the battery. I personally feel idle amps are more important than RPM amps.
Burning Brakes
Joined: Feb 2006
Posts: 1,024
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From: AL
But is that much airflow really necessary? I notice that most of the universal ones in my Jegs and Summit catalogs are rated at 2K-3K CFM. Would something like that work for a 450hp SBC without AC? (Aluminum radiator with a highflow waterpump)
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Too much talk about alternators, back on topic please.
If I go with a less powerful fan I might not need a new alternator. Has anyone successfully used a 2k-3k cfm electric fan with a potent small block w/o AC? (Also, my car has a manual trans)
If I go with a less powerful fan I might not need a new alternator. Has anyone successfully used a 2k-3k cfm electric fan with a potent small block w/o AC? (Also, my car has a manual trans)
Burning Brakes
Joined: Nov 2004
Posts: 821
Likes: 0
From: Ontario
I am going the Mark VIII route. Received my fan waiting for my DCC to arrive. I had already installed the 100 amp SI amp last year. I currently have a flex a lite extreme installed but have heard some good things re the Mark VIII and DCC.
Former Vendor
Joined: Jan 2000
Posts: 5,593
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From: Brighton
Note to the big air naysayers:
The dual fans GM uses on C5 Corvettes is only 1700 cfm with 450HP!
Last edited by Tom@Dewitt; Feb 28, 2007 at 07:13 PM.
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
I run the Mark VIII and the DCC--best setup ever.
I had the Flex-a-lites--they don't cut it at all.
The extra airflow is for the a/c system--it throws alot of heat into the radiator.
I have yet to see the DCC supply greater then 50% to the fan--at 50% the fan is almost noiseless. Except when the motor is turned off--it sounds exactly like a jet engine ramping down--a coolness factor of '10'.
I had the Flex-a-lites--they don't cut it at all.
The extra airflow is for the a/c system--it throws alot of heat into the radiator.
I have yet to see the DCC supply greater then 50% to the fan--at 50% the fan is almost noiseless. Except when the motor is turned off--it sounds exactly like a jet engine ramping down--a coolness factor of '10'.
Safety Car
Joined: Mar 2005
Posts: 3,503
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From: Raleigh NC
I have a Dewitts aluminum radiator and since I put the new seals in, the fan doesn't come on at all at speeds over 30 mph. I have not tested in summer yet...
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
Former Vendor
Joined: Jan 2000
Posts: 5,593
Likes: 631
From: Brighton
And there is certainly nothing wrong with that! My point is, and to answer the thread question, 2000 cfm with a good functioning radiator is plenty of air. You are proving that now.
Safety Car
Joined: Mar 2005
Posts: 3,503
Likes: 2
From: Raleigh NC
(240+) when the a/c was on. Now, if I had had one of your radiators it probably would have.
Pro
Joined: Jun 2004
Posts: 700
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From: Lantana TX
I sell about 150 of these per year for four years straight and I've never (not once) had anyone tell me that it wasn't enought air. Spals' dual 11 fans produce 2760 cfm and pull 25 amps. I know the Mark V fans are real popular on the CF right now, mostly due to the cost, but I still don't think much of mounting methods I've seen when compared to the bracket system we have.
Note to the big air naysayers:
The dual fans GM uses on C5 Corvettes is only 1700 cfm with 450HP!
Note to the big air naysayers:
The dual fans GM uses on C5 Corvettes is only 1700 cfm with 450HP!
