2. Engine Maps, Customers and Markets

In Chap. 1 the relationship between work, power, and engine speed was defined. It is this combination of work, power, and speed that is critical to an engine’s performance, the way it responds to changing demands, the way it “feels” to the driver. This subject will now be taken up in further detail. The work measured at the crankshaft of an engine is referred to as the brake work. The product of the brake work and engine speed (with the appropriate unit conversions) is the brake power. These terms reflect the history of engine testing, since early dynamometers typically consisted of friction brakes clamped around a spinning disk bolted to the engine’s crankshaft. While dynamometers have changed a great deal the fundamental principles remain the same.