No air density, no horsepower.

Chris Nelson loves a challenge. The owner of Energetic Motorsports and former head of R&D at ATS Diesel Performance owns various trucks, but the one he seems to enjoy the most is the one with the least horsepower. But this feeble powerplant isn’t being raced on the mean streets of Denver. No, he’s doing his best to eek every bit of horsepower out of his Toyota where those ponies don’t come easily–at ultra-high altitudes.

An avid off-roader, Chris recently took his 1980 Toyota Hilux high above Denver to an altitude of roughly 11,000’. The Canadian truck is powered by a 22re with stock internals. The only modern thing on the truck is his iDash DataMonster, which receives data from a MegaSquirt MS3 ECM. Being a tuning expert, Chris loves data. As he traversed the mountains above Empire, Colorado, he couldn’t help but notice the Density Altitude was reading 17,740 on his DataMonster. Curious about what horsepower his truck was making, he pulled over to have a drink and opened his laptop. Copying the data log from his iDash’s SD card to the laptop, he mapped the data. Because that’s just what data-obsessed tuners do when taking breaks during their rock crawling expeditions. With one glance, Chris revealed his Toyota, which produced 105hp when dyno’d at 5,400’, was making now producing a measly 66hp at 11,000’ and 54hp at 13,000’ in elevation. The lack of air density killed what little horsepower he had!

Density Altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the Density Altitude is the air density given as a height above mean sea level. In addition to ambient pressure, Density Altitude takes into account air temperature. As temps rise, air density decreases.

Chris created the chart below while atop the mountain. The horsepower falls as the Density Altitude increases. 

The only way he’ll ever get that power back is to add Density machines like a turbo and intercooler. Chris is crafty. Take a look at what he’s working on below. His phone may blow up as soon as Toyota fans catch wind.