Exhaust system design is a complex affair in some racing categories, especially where packaging around the engine is tight; motorcycles and single-seat racecars can be particularly challenging in this respect. If tubes are too small, have the wrong cross-sectional shape, are bent too tightly or are bent through too great an angle, engine performance can suffer significantly. On the dyno, many engine suppliers test with very durable dyno exhaust systems that are fairly straight and easy to...
In the first two instalments in this series on the prevention of fastener loosening, we talked about methods of chemical thread-locking before starting to look at some of the mechanical methods in common used, of which there are many. As mentioned before, axial thread interference is occasionally used, mainly as a way to improve the distribution of load between threads, but it has the happy coincidence of introducing some extra friction into the relationship, which is useful when trying to...
In recent years the Renewable Transport Fuels Obligation (RTFO) in Europe has caused much consternation to owners of older vehicles, including many vintage, classic and not-so-old race and rally machinery. Effectively requiring EU countries to introduce ethanol biofuel into gasoline at the rate of up to 5.75% by 2010, the push by the EU is now to increase this to 10% in the not too distant future and even further (20% and higher) thereafter. In a previous article I outlined some of the...
The operating range of a turbocharger is limited by the design of not just the centrifugal compressor but also that of the inward radial flow turbine which powers it. For the unit to work satisfactorily in service, the compressor wheel and casing on the engine air intake side have to be matched as precisely as possible to the exhaust gas-swallowing requirements of the turbine wheel and housing to ensure not only that the overall engine performance targets are met but also that both engine...
In past RET-Monitors for this keyword we have taken a general overview of oil additive technology, but it is worth looking at some additives in more detail, in this case molybdenum disulphide, often referred to as just moly. With the chemical symbol MoS2, this black crystalline compound occurs as the mineral molybdenite, the principal ore from which molybdenum metal is extracted. It is commonly used as a solid lubricant, thanks to its low-friction properties, which are similar to those of...