Fundamentals
Multec 3.5 Fuel Injector Application Manual
2-12
Delphi Energy and Chassis Systems
Revision: 11/05-1
2.2.6.3.2 Aromatics (approx. 35 %mass)
As aromatic concentration increases:
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Increases octane rating
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Increases energy content (increases fuel economy)
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Makes fuel more difficult to burn
•
Reduces fuel volatility
•
Increases self ignition temperature
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Increases soot formation
•
Increases deterioration of fuel system plastics and elastomer (swell)
•
Increases solubility of water
•
Reactivity of exhaust gas (smog formation)
2.2.6.3.3 Olefins (approx 10%)
Olefins are unsaturated hydrocarbons that can lead to deposit formation on
intake valves and injector tips. Olefins are created in the refining process.
Gasolines with high levels of olefins require additional detergent chemical
additives to prevent deposit formation on the injector director plate.
2.2.6.3.4 Others
Silicon and lead content in gasoline can be detrimental to oxygen sensors;
lead content can lead to products of combustion that can potentially cause
injector plugging and have been shown to be detrimental to both catalysts
and exhaust gas recirculation devices.
Sulfur in gasoline has been shown to reduce catalytic converter efficiency.
CARB regulations reduced sulfur to 30 ppm average 80 ppm max for Tier
2 emissions. The EPA will complete the phase in of these regulations in
2006.