Quote:
Originally Posted by lippy
Gear oil thins as it heats. That's it. The engine performs differently based on temperature. Colder air is denser and contains more oxygen, and adaptive engines can adjust by mixing more fuel to take advantage of this to make more power.
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It's actually the other way around. Older "non-adaptive" engines would make more power with denser air, since their systems would "naturally" adapt. That what a mass air flow sensors is all about. Even good old carburetors would do that by design.
Modern FI engines do the opposite and compensate (up to a certain extent) for lower density air by increasing boost to maintain rated power in varying conditions. Another way of putting it, is that they limit power in good conditions to keep thermodynamic reserve for poorer conditions. Piggy back tunes simply tap into that reserve.
Quite interestingly, I have achieved my highest top speed with my M4 at my local track on relatively hot and humid day. It was the total opposite with my E92 M3.
That being said, with higher boost and hotter air, the S55 will be a bit more laggy and less responsive even if it makes similar power.