Accurate measurement of fuel consumption is critical in quantifying the efficiency of an engine or predicting emissions. As part of a larger project, accurate instantaneous fuel consumption data was needed for a Ford LPG engine. A detailed review of literature did not provide clear recommendations on the number of data points or time duration for data collection. To provide a research basis for the number of data points and the duration of data collection, fuel consumption tests were conducted using up to 15 data points of percent fuel rate and up to 12 minutes of data collection. Based on analysis of these detailed test results, at least 3 data points (0%, 50%, and 100% of fuel rate) and 3.5 min of data collection are recommended for similar fuel rate tests for a LPG engine.
Hogan, John A., Watson, Dennis G. and Harrison, Tony V. "Data Points and Duration for Estimating Fuel Consumption of a LPG Engine." Agricultural Engineering International: the CIGR Ejournal IX (Nov 2007).