RON/MON Engine octane test operation are equipped with a throat venturi in carburetor. This venturi size is applicable for octane engine’s location.
RON Octane Engine Research Method octane test operation are equipped with a 9/16 inch throat venturi. This venturi size is applicable for octane engines located at all altitudes.
MON Octane Engine Motor Method octane test operations require that the venturi size be selected dependent on the altitude at which the unit is installed.
|Height above sea level of RON/MON Engine Location||Venturi Size|
|Above 1000m||3/4 inch|
NOTE: When the altitude at a location is close to that where venturi size changes, it is permissible to select whichever venturi size causes the RON/MON engine to rate toluene standardization fuel blends closest to the calibration values for the blend.