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      01-22-2013, 10:23 PM   #50

Drives: 2008 E90 M3
Join Date: Nov 2008
Location: Calgary

iTrader: (0)

Originally Posted by Gearhead999s View Post
You were also at about 3500 asl so of of course a FI engine will maintain its power compared to a NA engine which will have a loss of 2% per 1000 ft per altitude increase.Your increase compared to stock will be much greater than someone who operates much closer to a sea level pressure altitude like Laguna Seca.
Superchargers don't compensate for altitude like a turbo. They are pulley driven, so if pulley size is the same the boost pressure is the same. Unlike turbos which are controlled by wastegate which will maintain a constant absolute pressure and compensate for the thinner air of altitude.

This is of course a massive simplification, as we assume no efficiency losses as the turbo runs hotter (ideal compressor map) and the altitude also reduces spool time for turbos. But the point is the SC don't see the sme benefits as TC.