The SAE correction factor used by Dynojet assumes that lower air pressure at the sensor box means lower air pressure in the intake manifold, though, so at 5,000 feet the dyno is applying a 20-percent correction factor to compensate for a loss of air density that the engine never sees. This is fine if you are doing all your tests in Denver, but if you do one test in Denver and one test in New Orleans (the highest mountain in New Orleans is 12 feet above sea level) uncorrected numbers will be more accurate.

The SAE correction factors are only accurate over a relatively limited range, and the Dynojet software is smart enough to warn you when two runs with wildly different correction factors are being compared. The software in New Orleans can't check your glovebox for that last dyno printout from Denver, though, so you'll have to warn yourself.

This is where the dyno operator has to be extremely devious. If you mess with the readings that the computer uses to calculate the correction factor, you can alter the corrected output significantly. The one reading that the built-in sensors do not take automatically is humidity. The dyno operator has to enter the humidity correction themselves. Since the humidity is manually entered into the computer it is the easiest to alter. While humidity numbers are obviously suspect, the temperature can be faked pretty easily as well. We actually decided to try this one, just to see how easily it could be done.

Jackson Racing's Dynojet is set up with the weather data box mounted on a perpetually-shady portion of the dyno room wall. The temperature probe hangs under the box in the open air about two feet off the ground--right where most air intakes pull their air supply. Oscar Jackson pointed out that he has seen these boxes mounted where they were more easily accessed, and has even seen the temperature sensor hanging on a divider wall next to the computer, or in a drawer on the dyno bench. In the drawer, an unscrupulous dyno operator could put his or her hand around the sensor before doing a run, bumping the ambient temperature reading up into the 90-degree range. With it hanging on a well-placed wall, the sensor could be flipped from the shade into direct sunlight, where it could slowly bake up to a nice, warm temperature.

The wire on Jackson's sensor was only about two feet long, so we couldn't get it into the sun, and a shield prevented holding the sensor in a warm hand from having much effect. Instead, I cupped my hands around the sensor and blew on it. Within 30 seconds the dyno was reading 95 degree ambient temperatures even though our baseline run made a few minutes earlier had been in 66-degree air. We made another run with the engine breathing 66-degree air, but the dyno correcting for 95-degree air. Our corrected power jumped from 136 hp to 143 hp.

Originally posted by vapors2k
Marcus, check your PM. You are the rare and basically only person I've seen to post yourc charts from the toda cams.