| 200 feet is pretty low so we don't need to worry about it too much. As you get higher the correction factor becomes more important for accurate results. Denver is 26 times as high as we were the other day, so our numbers weren't corrected much for altitude at all. The reason NA cars and turbo cars aren't affected at the same percentage is because an NA car works off atmoshperic pressure, while a turbo car works off atmospheric pressure+boost. I'll use your car as an example: So you have: NA car= (atmospheric) Turbo = (atmospheric+boost) So at sea level you have: NA car= (14.7) total of 14.7 psi Turbo= (14.7 + 19) total of 33.7 psi We're using sea level as the baseline, so at sea level you both have 100% of your power. Now in Denver, at 5280 feet, the atmospheric pressure is 12.3 psi. So we have: NA car= (12.3) total of 12.3 psi, 83.6% of what he had at sea level.
Turbo = (12.3+19) total of 31.3 psi, 92.8% of what you had at sea level. So if you both had 500 hp at sea level, in Denver the NA car now has 418 hp and you now have 464 hp. Since the boost level is added on top of the atmospheric pressure and remains constant regardless of altitude, the more boost you run the less altitude will affect you. Quick comparison at Denver's altitude with a NA car, car running 5 psi, a car running 10 psi, and a car running 20 psi: NA car = (12.3) total of 12.3 psi, 83.6% of sea level 5 psi turbo =(12.3+5) total of 17.3 psi, 87.8% of sea level 10 psi turbo=(12.3+10) total of 22.3 psi, 90.2% of sea level 20 psi turbo=(12.3+20) total of 32.3 psi, 93% of sea level
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