Small CFM gas powered air compressors won’t perform as well at 5,000 feet of elevation as they do at sea level. They may fail, bog down, or supply less air power. But why don’t gas combustion engines perform optimally in elevation?
It all comes down to the physics of gas combustion engines.
Oxygen, Fuel & Spark
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 engine horsepower. As the amount of available oxygen decreases, the engine must work harder to meet demand. Therefore, when the elevation gets too high, combustion engines may fail to start, or may start to bog down, or stall.
Why Engine Size Matters
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 powered air compressors, generators, and pumps, are susceptible to performance issues at elevation.
VMAC G30 at High Elevations
In terms of VMAC air compressors, extremely 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.
Field tests demonstrate that Honda gas engines deliver sufficient power for VMAC’s G30 and G30+GEN to maintain full air output at elevations up to 3,500 feet (1,067 meters). These altitudes are generally found in major mountain ranges.
Webinar Answer: How Does Elevation Affect The Operation Of VMAC’s G30 and G30+GEN?
How to Solve High Elevation Issues
Now that we’ve identified the problem, let’s talk about three solutions for the challenges with gas engines at high elevations:
1. Carb Rejetting
Using the G30 as an example, Honda offers parts for carb rejetting that enable the GX390 engine to operate 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.
2. Air Receiver Tank
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. Air receiver tanks play an important role in compressed air systems and have many benefits.
3. Alternate Engine Type
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 driven compressors are all options that can withstand higher elevations.
VMAC products designed for work at high elevations include:
- UNDERHOOD 40, 70 and 150 rotary screw air compressors
- Direct-Transmission Mounted air compressors & multi-power systems
- Hydraulic driven 40 CFM and 60 CFM rotary screw air compressors
- Diesel driven 60 CFM rotary screw air compressor
- Diesel driven Multifunction systems, providing 6 different power sources, including a 45 CFM air compressor
- Gas powered Multifunction systems, providing 5 different power sources, including a 45 CFM air compressor
