Primo Cars

One bar is roughly the pressure experienced at sea level. It’s the same as 14.5 pounds per square inch (psi) or 0.99 atmospheres and is the metric unit used to measure pressure. It is to describe turbo boost or the pressure generated in a fuel injection system.

A flexible ball-and-socket joint used primarily in front suspension units because it can accommodate a wide range of angular motion. The ball joint offers relatively free movement between components while holding them together.

Generally employed in pair, there are contra-rotating shaft, geared together and carrying opposed balance weights. They can be driven at engine speed to cancel out primary reciprocating imbalance, as in old Ford V4 engines and some three-cylinder units. More usually driven at twice engine speed to smooth out vibrations caused by secondary imbalance, as found in four-cylinder Mitsubishi engine.

The process of cancelling out the force created by imbalance in rotating components and by the reciprocation of pistons and conrods. Imbalance creates internal stresses in engine structure and causes unwanted external vibrations that are fed into the body shell – bed for reliability as well as comfort. Rotational imbalances are easily corrected, but balancing of the reciprocating masses are much more difficult. Reciprocating imbalance can be categorized mainly as primary (oscillating at engine speed) and secondary (oscillating at twice engine speed). The best approach is to balance the motion of one piston against that of another – thus straight-six, V8 and V12 engine can have perfect primary and secondary balance. An ordinary in-line four is in primary balance only – hence the use of balancer shafts.

The oil pans or sumps of some competition engine have thin metal plate or baffles that reduce the amount the oil is sloshed around under hard cornering and other heavy gravitational forces. This stops the engine being starved of oil when running at high rpm.

When a fresh unburned charge of fuel combusts in the exhaust system due to leakage from an open exhaust valve, it is known as backfire. It is sometimes heard on trailing throttle as a car slows down.