Motor Octane Method

Motor octane method a test for determining the knock rating of fuels for use in spark-ignition engines see also Research octane method. 

There are two standard procedures for determining the octane numbers Research or FI and the Motor or F2 methods. The corresponding numbers are designated as RON (Research Octane Number) and MON (Motor Octane Number) which have become the international standard. 

Engine knock is measured by two ASTM methods, ASTM D-2699 and D-2700. Method ASTM D-2699 is identified as the research octane number (RON) and method ASTM D-2700 is identified as the motor octane number (MON). The primary differences between these two methods are summarized in TABLE 3-3. 

ASTM Method D 2699 the motor octane number is determined using ASTM Method D 2700. The Antiknock Index is the average of the Research and Motor numbers. Octane numbers are determined using n-heptane that has an octane number of 0, and isooctane that has an octane number of 100 [2.2]. 

Surveys of gasoline quality in Europe and North America in Spring, 1969, show octane numbers by the "Research and Motor test methods, as given in Table 2 20>. 

The more severe conditions of the motor method have a greater influence on commercial blends than they do on the reference fuels. Thus, a motor octane number (MON) of a commercial blend often has a lower research octane number (RON). Consequently, blended fuels use an arithmetic average of both ratings—MON and RON—and can be abbreviated as (R + M)/2. 

The original CFR test conditions appear in the second column of Table 7.2. These constitute the Research method and assign the fuel a Research octane number (RON). It was found that typical fuel susceptibility to knock in practical engines did not correlate sufficiently well with this test and one with rather more severe conditions - the Motor method, giving the Motor octane number (MON) - now also is used. These conditions are given in the third column. The inlet manifold temperature and speed have been increased, spark timing advanced, and a shrouded inlet valve fitted to... 

Due to the Clean Air Act, increasing attention is paid to the production of alkylates, which is a very clean burning fuel and has a high MON (motor octane number) with a low octane sensitivity and moderate vapor pressure. Commercially operated alkylate production uses a liquid acid catalyst such as H2SO4 or HE, resulting in problems associated with cost, apparatus and the environment [47]. New synthetic methods utilizing solid acid catalysts have been developed but no commercial process has emerged due to fast catalyst deactivation [48]. 

ASTM D2700, Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel, ASTM International. 

Uee Motor method with Motor octane columns and Research with Research columns. 

In order to characterize the behavior of motor fuels or their components with regard to knocking resistance but without involving chemical composition criteria which are complex and not easy to quantify, the traditional method that has been universally employed for more than 50 years consists of introducing the concept of octane number. 

Measurement of octane numbers is carried out using a reference motor called CFR (Cooperative Fuel Research), referring to a series of studies conducted in 1928 in the United States in order to standardize the methods for characterizing motor fuels. 

R — Research method octane rating, ASTM D2699 M = motor method octaine rating, ASTM D2700. 

Figure 2. Comparison of F-2 (Motor Method) Octane Numbers of Debutanized Gasolines from Platforming and Thermal Reforming of Pennsylvania Straight-Run Gasoline...

F-2 CLEAR OCTANE NO. OF DEBUTANIZED GASOLINE Figure 8. Lead Response (Motor Method) of Platformate and Thermal Reformate from Mid-continent Naphtha... 

Blending octane No. Motor method in 50-50 blend with 72 octane No. reference fuel blend. 

The boiling point, refractive index, and density of the olefin derivative of any paraffin were shown, by use of Table III, to stand in the onier of their olefin type. Table X contains the engine data of the olefin derivatives of 2-methylpentane and 3-methylpentane, recorded in the order of their olefin type. No consistent relations between octane numbers or critical compression ratios are obvious—but the blending octane numbers of these branched olefins, as measured by both the research and Motor methods, do generally stand in the order of their type. Two olefins of type III form exceptions, the exceptions being in one case too high and in the other case too low. 

---