Why is the 2" hole bored parallel to the housing
instead of perpendicular to where it is penetrating
the housing for a smaller overall hole?

The air is actually flowing upwards as it enters the housing.
A perpendicular opening would force the air to make more of
a right  angle. That is one reason. The other reason is it easier  to set
it up on a mill table :)

A third reason is that is the way Mazda did it on the Le Mans engine.
See the attached drawing.

It is probably not that critical because some p-ports with
perpendicular holes also seem to generate about the same amount of  power.

Paul Lamar

Another reason is that it would be very difficult to make the very
short,  90 degree plus bend, to wrap the intake over the top of the
engine. With the insert parallel e bends are 90 degrees.  This may
change if composite intakes are developed.  I think the perpendicular
to housing p port might take a performance hit as well since the time
open would be decreased.     Jerry

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