Fan CFM?

[metalhed1988]

I have searched here and elsewhere. Does anyone know what the CFM is on the Vmax fan? The reason being is that I am building a custom Vmax and I want to change the fan for aesthetics because it will be more visible and possibly for performance if I can find the technical information.

 

[Zeus36]

Not the answer you were looking for, but this may get you started:


According to the general fan law governing axial fans, you will need to know the fan blade diameter and pitch (blade tilt or attack angle) along with the rpm variable to calculate CFM. In this example, a small household fan on a stand has a three-bladed plastic fan with a 1-foot diameter and an 8-inch effective pitch. This means that each revolution of the running fan blows the one-foot-diameter column of air coming through the fan 8 inches toward you after accounting for efficiency losses. The fan is running at 1,200 rpm.
The amount of air this fan pushes can be calculated.
Calculate the linear velocity of the air through the running fan. If each revolution moves the air 8 inches, then 1,200-revolutions per minute multiplied by 8 inches means the air 9,600 is being moved at inches per minute, or 800 feet in one minute. Another way of looking at it is that the fan is moving an 800-foot-long column of air that is 1 foot in diameter through space each minute.
Calculate the CFM (volumetric flow of air) at 1,200 rpm. The volume of the column of air described in Step 2 is pi (3.1416) x fan radius squared (0.5-feet squared) times the column length in feet. This would be 3.1416 x 0.25 square feet x 800 feet = 628.32 cubic feet per minute at 1200 rpm.
As a general rule of thumb, follow these minimum cubic feet per minute (CFM) ratings when using an electric fan as the primary cooling source on a basic automobile engine:
1,250 CFM for a 4-cylinder
2,000 CFM for a 6-cylinder
2,500 CFM for a 8-cylinder

Once you know the minimum CFM required, you need to determine what will physically fit. This is easiest to do if you remove the belt-driven fan and fan shroud so that you can accurately measure the radiator and the distance between the radiator and engine components.

You should also measure the radiator core, which is the finned surface between the two tanks. You’ll want to select a fan that covers as much of this space as possible. In many cases, you will be better off with a dual fan because the shroud will pull air through a larger area of radiator than a single fan.

Next, measure the distance between the radiator core and the closest engine component. You can then supply these dimensions to your sales rep.

Choose Pusher or Puller
Electric fans are available in pusher or puller designs. Pusher-style fans mount on the front of the radiator and blow air through the radiator core. Puller-style fans mount behind the radiator and draw air through the core.

Puller-style fans are recommended for applications in which the electric fan is the primary cooling source. A pusher-style fan can be used as an auxiliary cooling source, but you should sure make the fan covers as much of the radiator core as possible. This goes back to measuring and determining the right dimensions for your fan.

- IMHO -If you are going for an aftermarket fan, say 1250 CFM per the text above (for a four-cylinder car) it would most likely exceed the stock fan - what ever that actually is.

Check this out: http://www.holeshot.com/parse.php?file=old/vmax/vmx_cp.html

 

[metalhed1988]

thanks for the info. I found some 7" and 8" fans but they don't push 1000 cfm. They are fairly inexpensive so Ill probably just pick one up for comparison.