Doghouse Fan Shroud Velocity Ring
Brought to you by Awesome Powdercoat, this is a Doghouse fan shroud ('71 and later) velocity ring. It improves airflow through the fan shroud by 5.25% for an OEM fan and by 6.41% for my Evolution Two fan for Doghouse fan shrouds.
With the Evolution Two fan for doghouse fan shrouds, the total increase is 23.27% over just the OEM fan with a velocity ring, and 28.52% over the OEM fan without the velocity ring.
IMPORTANT NOTE: In my testing, the 36 hp style Doghouse fan shrouds have an air inlet that is smaller than OEM which restricts airflow considerably (around 2.5% less airflow compared to OEM), and I do not recommend running one of the 36 hp style Doghouse fan shrouds, regardless of vendor as they all suffer from the same problem, without a velocity ring.
Installation Instructions
The tabs for the velocity ring are already bent, which makes the installation orientation obvious, in that it will only go on one way.
You can either weld it in place using the holes in the tabs, or you can drill holes using the holes in the tabs as a guide, and use pop rivets.
Welding it in place is the best option, but not everyone has a welder or access to a welder or perhaps has the skill with a welder on thin sheet metal.