Gasoline engines with throttles develop vacuum in the intake manifold. That vacuum provides information about how the engine is running and can be used to diagnose problems.
I made previous video that explained the details of engine vacuum and MAP. I received some questions about why it was necessary and that it seemed wasteful to have the inefficiency of manifold vacuum. I also had some questions about supercharged or turbocharged engines effect on vacuum.
In this video, I will discuss those questions and consider the alternatives to gasoline engines with throttles and vacuum. These include stratified charge engines and diesels.
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