Quote:
Originally Posted by wulfgang
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).
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Do you mean ?
Turbo at Sea level : 1bar + 0.5bar(boost) = 1.5bar
Turbo at 1200m altitude: 1bar*0.86 + 0.5bar(boost) = 1.36bar
Supercharger at Sea level: 1bar + 0.5bar(boost) = 1.5bar
Supercharger at 1200m altitude: 1bar*0.86 + 0.5bar*0.86 = 1.29bar