Quote:
Originally posted by Ashton
Actually, the lead in leaded fuels wasn't to stop knocking
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Lead was originally added to boost octane rating for cheap. The higher an octane rating a fuel has, the less prone to knocking it is. The effeect on valves is not a primary one, but a secondary one. After combustion, the lead coats the valves , protecting them from the combustion energy. In turn, that would allow the factory to make valves slightly less strong, but I'm not sure of how much of an effect it really has.
The more compression an engine has, the more prone to "knocking" it is, and late 60s engines had high amounts of compression. When an engine knocks, it compresses the gasoline so much it spontaenously ignites ( sorta like a diesel engine would, but in this case a very undesired effect).
The fuel additives shouldn't have lead in them, as lead destroys modern cars catalytic converters. No cats is ok on a pre-catalytic day, but on modern cars it's illegal ( even though people do it...)
Read up here at howstuffworks if you don't believe me. They are a credible source.
http://science.howstuffworks.com/gasoline.htm