Leaded Racing Fuel Specifications.
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| Definitions | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MOTOR OCTANE: (a) CFR Tested @ 900
rpms, timing is varied with compression ratio, fuel is
preheated to 300deg, intake air is preheated to 100deg. (b)
Motor Octane, measured under varying load is definitely the
most representative octane measurement for REAL WORLD
HI-PERFORMANCE ENGINE APPLICATIONS.
R+M OCTANE (R+M): (a) this method of measurement consists of adding together both Motor and Research Octaneās then dividing them by two. (b) This is the number in the yellow box, which you see at the gas pump. (c) This number should only be used in determining which octane to use in your stock street car or tow vehicle. RESEARCH OCTANE (RON): (a) CRF tested @ 600rpms, fixed timing at 13deg BTDC, fuel pump is not controlled and Intake air is varied with the barometric pressure. (b) This is basically a no-load test and this number should not be used in determing which fuel to use in your race engine. SPECIFIC GRAVITY (SG): (a) This is the weight of fuel compared to water, water being 1.00. If race fuel were .750 (SG) it would weigh and the weight of water. (b) The less dense the fuel (lower specific gravity) the higher the BTU content, and the better the stability of the fuel at higher RPMās. (c) The lower the specific gravity of the fuel, the more crucial the jetting becomes, and the easier it becomes to run lean. (d) The combustion speed is determined primarily by the (density) of the fuel mixture. (e) The higher the specific gravity, the cooler the fuel charges. |