Not all air rams are equal in performance
That's why Airflow Snorkels are designed, manufactured and tested to maximise performance.
In general, air rams need an open face - preferably without a screen (which deflects airflow). The ratio of the open face of the air ram to outlet aperture should be a minimum 1.4:1. Any less than this and there will be insufficient cyclone action to effectively separate out the contaminants.
Any deflection in the incoming air flow can dramatically affect the efficiency and output. This can be caused by:
- Close proximity to a bonnet/hood
- A foil/curved top on the air ram
- Turning the air ram away from the direction of travel
- Where the air ram design makes the air go back on itself at an angle greater than 100°
In the case of the air ram being turned away from the direction of travel the result is lessening of the positive pressure that is desirable. In the extreme, a vacuum is caused (i.e. turning the air ram backwards which may cause engine damage and should only be used over short distances).
Incorrect design of the air ram can cause excessive induction noise, lack of separation and air blocking by vortex of the air at various speeds. This air blocking will limit air flow. This is a common occurrence where design and look of the air ram is put ahead of its functionality.