Re:2.5 AFM & DTM & F1 intake

[christian147@domain.elided]

> some sources say you want the velocity to be no higher than .6 mach,

That is Z,  relative mach index,  you need to know pressure and temp in
the intake to compute Z.  Most modern sources suggest 690 fps as the
target of port velocity, long way away from the ~1100 fps usually quoted
as mach at STP, because of the low density air in the intake has a lower
mach speed.  Some builders will go as high 730 fps but with the knowledge
that they are on the verge of sonic shock waves shunting down the port. 
Some builders will only go as high as 650fps on an all out customer
engine insure it gets no shock waves in the heat of battle.

Chris Hall
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