1.8: Cylinder arrangements and firing orders
1.8 Cylinder arrangements and firing orders
There are three arrangements which may be used for an engine.
In-line engine The cylinders are arranged in a single row, one behind the other. They may be vertical, as in most modern light vehicles, horizontal as used in coaches where the engine is positioned under the floor, or inclined at an angle to allow for a lower bonnet line.
Vee engine The cylinders are arranged in two rows at an angle to one another. The angle for two-, four- and eight-cylinder engines is usually 90 . For six- and twelve-cylinder engines the angle is usually 60 . This is illustrated in Fig. 1.11.
Figure 1.11: A high-performance V eight-cylinder engine
Opposed piston or cylinder engine This is where the cylinders are at an angle of 180 apart and usually positioned horizontally (see Fig. 1.12).
Figure 1.12: Horizontally opposed cylinders with divided crankcase
Take a look at each type of engine and draw up a simple list of the main advantages and disadvantages, e.g. is it easier to work on for the mechanic? Does it allow for a lower bonnet line? Is the exhaust system easier to arrange? If so, what advantage/disadvantage is there in this?
When considering multi-cylinder engines and firing orders, the power strokes should be spaced at equal intervals to give the smoothest possible running of the engine. Each interval is equal to the number of degrees per cycle of operation. This will be...