Quote:
Originally Posted by Gary in La.
Modern diesel engines use an additive called DEF which is a urea based fluid. It helps remove the nitrogen oxide which is detrimental to cat converters and the air we breath.
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Nitric oxides are not detrimental to catalytic converters... at least the ones I'm familiar with. (ones used in gasoline engines)
Gasoline catalytic converters: Nitrogen Oxides are produced from high compression. The requirement to reduce nitric oxides is the reason compression ratios were lowered in 1972. Nowadays, compression ratios are back up! Newer converters have a first stage that breaks down nitric oxides into nitrogen and oxygen.
The first converters were not capable of breaking down nitrogen oxides. The main role of these was to finish combusting unburned hydrocarbons (incompletely burned fuel)... and to convert carbon monoxide into carbon dioxide. They relied on an air pump mounted to the front of the engine to supply the needed oxygen.
Modern converters THRIVE on nitric oxides, as THOSE are what provide the oxygen to finish burning unburned hydrocarbons and convert CO to CO2. These have allowed compression ratios and power to make a major comeback.