Pistons rings are items that we are perhaps not accustomed to having to worry too much about, especially if our race engine is not of bespoke design. Once ‘bedded-in’, they normally form a reliable seal between the piston and bore. However, there is a particular case where piston rings can cause a problem owing to a vibration condition which is due to a combination of factors centred around the fundamental geometry of the engine, the mass of the piston rings, engine speed and the...
There are a number of valid reasons for wanting to improve the surface finish of race engine components. Aesthetics, friction reduction and durability can all be enhanced by reducing surface roughness, although the aesthetic aspect will always be subject to the opinion of the beholder. Controlled surface roughness though is very important on some components – unless you are very sure about what you are doing, mirror-finishing a piston skirt or cylinder liner for example can lead to...
The focus on downsizing powerplants in many racing series, for example Formula One and sportscar racing, has seen direct-injection (DI) gasoline engines become more common. The development of such engines is no easy task and requires extensive simulation and testing to ensure that systems are working to their optimum. When it comes to testing and analysing factors such as injector spray patterns and the combustion process itself, much reliance is placed on CFD simulation. However,...
The Le Mans 24 Hours is one of the toughest tests of racecar endurance in the world. Nowhere else are components and personnel presented with the same combination of relentless racing, an unforgiving circuit and ever-changing track conditions. In the past, transmission reliability has proved particularly troublesome and, while the current generation of Prototype and GT gearboxes are generally reliable, constant r&d by manufacturers is required to ensure they stay that way. The internals...
In engines with overhead camshafts, the choice of cylindrical translating followers is very common, both in passenger car and bespoke race engines. These are in the form of ‘inverted buckets’ (also called tappet buckets), with the flat ‘bottom’ of the bucket being the contact surface between cam and follower. Other types of cam followers, such as finger followers, may offer a number of advantages – including lower reciprocating mass,...