Submitted by Marvin Mellage.
The following information was taken in part from the Model-A Times magazine. There has been a lot of discussion about which is the best fan to keep that Model-A temperature the coolest. Is the original 2-blade metal fan, the later 4-blade metal fan, or the after-market 6-blade plastic fan the best?
For the tests a sophisticated instrument was used to measure the air speed in MPH (Miles Per Hour) at three different engine RPM’s (Revolutions Per Minute). The results are not scientific but do give a good indication of which fan produces the most air flow. The tests were performed on a stationary vehicle.
The following tests indicated the fan air flow MPH speeds with engine speeds of 500 RPM, 1,000 RPM, and 1,500 RPM. The measurements were taken at the front right corner of the engine block.
|
Fan |
Engine @500 RPM (12 MPH ground speed) Air Flow |
Engine @1000 RPM (25 MPH ground speed) Air Flow |
Engine @1500 RPM (37 MPH ground speed) Air Flow |
| 2 Blade | 7 MPH | 18 MPH | 25 MPH |
| 4 Blade | 11 MPH | 24 MPH | 32 MPH |
| 6 Blade | 8 MPH | 22 MPH | 34 MPH |
The above Air Flow test results indicate:
- The 2-bladed fan produces less air flow than either the 4-bladed or 6-bladed fan.
- The 4-bladed fan produces the most air flow up to 1,000 rpm.
- The 6-bladed fan produces the most air flow at 1,500 rpm and higher.
Summary:
The 2-blade fan should be adequate if the cooling system is up to par. If not, more fan blades might be needed. A car’s higher speed will increase air Flow through the radiator, but also increase engine heat. Remember, a good clean radiator, correct coolant, and tight fan belt are essential to good Model-A cooling.