Description

This article is from the Gasoline FAQ, by Bruce Hamilton with numerous contributions by others.

6.5 What does the Motor Octane rating measure?

The conditions of the Motor method represent severe, sustained high speed,
high load driving. For most hydrocarbon fuels, including those with either
lead or oxygenates, the motor octane number (MON) will be lower than the
research octane number (RON).

Test Engine conditions                Motor Octane 
Test Method                         ASTM D2700-92 [104]
Engine                       Cooperative Fuels Research ( CFR )
Engine RPM                               900 RPM
Intake air temperature                    38 C
Intake air humidity           3.56 - 7.12 g H2O / kg dry air        
Intake mixture temperature               149 C 
Coolant temperature                      100 C
Oil Temperature                           57 C
Ignition Advance - variable     Varies with compression ratio
                                 ( eg 14 - 26 degrees BTDC ) 
Carburettor Venturi                       14.3 mm

 

Continue to:

• prev: 6.4 Why are two ratings used to obtain the pump rating?
• Index
• next: 6.6 What does the Research Octane rating measure?

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