Quote:
Originally Posted by AVOturboworld
Technically, you don't have to turn up the boost on a turbocharger to compensate for altitude because it will do it for you. If you drive from 0 feet to 6000 feet, the boost pressure read by your boost gauge will show the same peak boost levels being reached. That's because the wastegate spring pressure doesn't change, and since it was calibrated for, say, 6psi, it will just bleed less and less air pressure off until it runs too far out of it's efficiency range.
|
The wastegate diaphragm responds to gauge pressure (psig), not absolute pressure (psia). The wastegate spring pushes against the intake manifold pressure, but there is atmospheric pressure on the other side of the diaphragm. Since the atmospheric pressure is lower at 6000', it takes less manifold pressure to push the spring than it would at sea level. Therefore, even though the boost gauge reads 6 psi in the mountains, it is not the same as 6 psi at sea level. (Sorry, not trying to lecture a turbo kit manufacturer; in my opinion, your post makes it seem like one will automatically make the same power at 6000' as one would at sea level just because the boost gauge still reads 6 psi.)
So I don't see how the turbo can automatically compensate for the elevation unless you use a boost controller that has an absolute MAP sensor. A simple wastegate won't do it. If it did, your boost gauge should be reading something like 8-9 psi in the mountains (the boost gauge also reads gauge pressure, not absolute pressure).