Confusing Cofigurations
Petrol engines provide the motive power for the vast majority of modern cars, and after more than a century of development they have become extremely efficient and reliable. All petrol engines are based on the same principle: if you mix petrol and air and then compress the mixture, a tiny spark will cause it to explode; the power of this explosion can be used to work an engine.
The basic petrol-engine design consists of a hollow metal cylinder, in which a close-fitting piston is free to move up and down.
The piston is connected to a rod, which is pivoted where it joins the piston. At the other end of the rod, called the connecting-rod, is a bearing that allows it to rotate on the crankshaft, which is itself free to rotate. If the crankshaft is turned, the piston will go up and down, and of course, if the piston is moved up and down, the crankshaft will turn.
The piston is made so that it is an air-tight fit in the cylinder and as it moves upwards any air in the top of the cylinder is compressed. All that is necessary to make this into an engine is to devise some means of getting a petrol/air mixture into the cylinder, some means of making a spark to make it explode, and some means of getting rid of the smoke and gases after the explosion.
Almost all car engines use the four-stroke principle – first used by a man named Otto in 1876. (The other popular type of engine, called the two- stroke, is used very rarely now, mainly because of its generally inferior reliability.) The four-stroke principle is so called because an explosion takes place in the upper part of the cylinder – known as the combustion chamber – once every four movements of the piston (two up strokes and two down strokes). In the four-stroke engine, the combustion chamber has two valves, called the inlet valve and the exhaust valve. Some engines use four cylinders, some cars like the Bentley for sale use 12 in a W configuration, others like the Ferrari 458 for sale use 12 cylinders, but in a V configuration, and then there is the McLaren MP4 12C, which is a V8 with twin turbochargers.
