The Reno air racers have turbochargers and or superchargers so they say they pray for hot weather at 5000 ft cause they can go faster than in lower, colder air. Density altitude, and its not hard to see 7,000-8,000 ft at Reno, does have a big effect on normally aspirated engines. No one at Reno races for the money cause all there really is at the end of the race is bragging rights.
But back to Burt. His life is much more fasinating than the movie. He gets married, has 4 kids, gets divorced when he is about 47 in about 1947, and quits his motorcycle salesperson job. Yet somehow he supports himself enough to go to the states on a recon trip to the salt flats, Edwards AFB and Mexico after buying a buick straight 8 (1959), and returns year after year with his constantly changing 1920 Scout. What I think would be fasinating is to pay the museum with the true "Munro" special to take it appart and make measurements and pics of what he did to get the engine to make the HP and make it live with what ever fuel he was using. I think at least some of these salt flat bikes have been put on a dyno so you would know about what HP would be needed to go as fast as he did. That fasinates me as well as what old cracked tuibe tires did he use that could withstand the heat and forces of 180 mph....