Compensating for altitude (was: '87 5KTQ performance trouble)

[Audial <Audial@aol.com>]

Mark Pollan wrote:

>Does anybody know how to adjust based on elevation.  This might help
>those living closer to Audihala.

Here's a table that I found that is probably very accurate (it's for SCUBA
divers).  The theoretical foundation of this table takes into account such
things as the variation in the temperature of the atmosphere at different
elevations:

Z(km)     P/P0
-------      --------
   0           1
  0.5       0.942
  1.0       0.887
  1.5       0.834
  2.0       0.785
  2.5       0.737
  3.0       0.692

Z is elevation in kilometers, P is pressure in atmospheres, P0 is pressure at
sea level.  The equation that produced these values is:

P(z)/P0 = (1 - 0.02255z)^5.256    

1.0 BAR = 14.7 psi = 760 mm Hg = 29.92" Hg = 1 atmosphere

So at one mile of elevation = 1.609 km elevation, the atmospheric pressure
should be ~ 0.823 atmospheres and your boost gauge will probably read 0.8 if
it read 1.0 at sea level.

So if you want to take your Audi to the Himalayas, you can figure out what the
gauge should read!

Best Wishes,
Alex