Fuel Quality Calculator

Cummins Westport natural gas engines can operate on CNG, LNG or biomethane that meets Cummins published fuel specifications.

Pipeline natural gas fuel quality can vary on a regional and seasonal basis. LNG fuel quality may change if it is held in storage for extended periods of time. Check with your fuel provider regularly to ensure that natural gas fuel quality, in particular, the methane number, meets engine requirements.

Minimum Methane Number
The minimum methane number requirement for Cummins Westport engines is:

  • C Gas Plus, B Gas Plus, and L Gas Plus:  65 
  • ISL G, ISX12 G, ISB6.7 G, and all 2018 engines: 75 

History and Methodology
Before November 2015, Cummins Westport’s fuel quality calculator used a Methane Number (MN) calculation based on the Society of Automotive Engineers (SAE 922359 Eqn 4). In November 2015, this was changed to a Cummins Proprietary methane number calculation. The Cummins Proprietary calculation provides a more accurate representation of the true Methane Number of the fuel. We recognize that the two methods will result in different calculated methane numbers for a given fuel composition. However, we expect that this difference will be small and will not likely change the acceptability of most automotive natural gas fuel compositions.

If the calculated methane number of a specific fuel composition is just above or below the acceptable limit, please contact us to discuss. Hourly and daily variation in fuel composition may have a greater impact on the resulting methane number than the calculation method used. The Cummins proprietary methane number calculation is a numerical, regression-analysis based method using an extensive set of experimental test data. While neither this data or the resulting calculation can be shared, this fuel quality calculator can be used to determine methane number for a given fuel composition.

Using the calculator
This fuel quality calculator will help you check that your fuel meets the required specifications for use in the following Cummins Westport engines. 

ISX12N • L9N  B6.7N  ISX12 G • ISL G • ISB6.7 G  L Gas Plus • C Gas Plus •
B Gas Plus

Fill in the Fuel Composition values so that the total equals 100%. Results are calculated automatically. Methane Number, Lower Heating Value, and Sulfur Content criteria must be met to pass a given fuel for a specific engine.

Click here to go to the Fuel Quality Calculator

MOBILE - Fuel Quality Calculator

Green   Pass:  Fuel composition acceptable.

Amber   Pass:  Fuel composition acceptable, but methane number is close to minimum specification. Be aware of potential variations in fuel composition as described above.

Red   Fail:  Fuel composition does not meet Cummins Westport requirements.