It all comes down to the physics of gas combustion engines.
Combustion engines work by combining three critical elements: oxygen, fuel, and a spark. Engines need the right amount of each of these elements, at the right time, for optimal performance. But a change in elevation changes the available oxygen.
When elevation increases, air density decreases, which also decreases the amount of oxygen in the air. This decrease in oxygen makes it harder for combustion engines to do their job. The engines will try to compensate with more fuel, but this compromise won’t always be enough.
There is also proportional decrease in horsepower as the amount of available oxygen decreases, and the engine must work harder to meet demand. Therefore, combustion engines start to bog down, stall, or fail to start when the elevation gets too high.
Not all engines experience issues with elevation. Larger engines can typically handle the decrease in oxygen because there is more available horsepower for auxiliary equipment. Even at higher elevations, large engines usually have enough power to meet those needs.
However, smaller engines don’t tend to have horsepower to spare. Small combustion engines, like those found in standalone gas driven air compressors, generators, and pumps, are susceptible to performance issues at elevation.
In terms of VMAC air compressors, extraordinarily high elevations will impact the GX390 engine used in the G30 air compressors and the G30+GEN air compressor/generators. As with any gas engine, output is also dependent on ambient temperature and humidity.
Our field testing shows that the Honda gas engines will provide full air output at up to 3,500 feet of elevation. These elevations are typically only found in large mountain ranges.
Now that we’ve identified the problem, let’s talk about three solutions for the challenges with gas engines at high elevations:
Using the G30 as an example, Honda offers parts for carb rejetting that enable the GX390 engine to run at elevations up to or above 10,000 feet. Carb rejetting changes the air-fuel mixture so that it’s closer to the air and fuel levels at lower elevations, which helps the engine perform better at those higher elevations. Operators who want to rejet their engine can purchase the parts and perform the modification, or work with an authorized Honda equipment dealer.
An air receiver tank can be used to build up a storage of compressed air. This stored air can often provide enough compressed air to complete intermittent tasks in small bursts.
If the elevations are too high and the air compressor is failing or won’t function at all, you likely need to use an air compressor system with a different power source. Hydraulic, diesel, and vehicle engine powered compressors are all options that can withstand higher elevations.
VMAC products designed for work at high elevations include: