Formula?

[Jeff Chambers]

Was the 2000' the physical altitude or the density altitude? More times than not, the density altitude far outweighs the correction required for the physical altitude. For example, Norwalk (my home track) is only at 742' physical altitude but during the summer months its pretty common for the density altitude on any given day to be in excess of 2500'. This is because of the combined effects of barometric pressure, humidity and temperature. The last two times I've been out for TnT, the barometric pressure has been in the mud at less than 28.9 in-Hg. That's a killer for an N/A car....the density altitiude was at more than 3800' both times. That's why you'll see the serious racers with a weather station; to help them really tune to the conditions. Being a carbureted car, I can usually tune more than two-tenths of a second based on weather alone. That's huge when you're racing heads-up.