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Old 06-09-2013, 08:25 PM   #11 (permalink)
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Air density from freezing to boiling point of water drops by 25%. Basically that means when you go to those two extreemes you have only 3/4 of the air mass. Atmospheric pressure also drops by 50% at 18k feet altitude.

If you needed 50% of your available manifold pressure to maintain 70 MPH then you would need 100% at 18k feet or everything the engine could produce, not considerating the lower aero drag at that altitude.

Better throttle response will always occur at lower intake temperatures, to the point where temperatures get low enough to prevent proper atomization of the fuel air mixture.
Like the winter when germany invaded Russia in WW2. Try starting your car in 40 below temps (hint 40 below farenheit and celsius are the same temperature).


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