The overhead valvetrain is no longer widely used in much of the world, although it retains a firm grip on the North American market and engines based on it also appeal to the Australian motorist. Perhaps the advantage of having historically had low fuel prices compared to Europe, combined with long and deserted roads between places of note, makes such engines appealing. In racing, the overhead valve (pushrod) engine has a mandated stranglehold in NASCAR, and where large-capacity engines...
Valve collets (also known as valve keepers, valve cotters or valve locks) are not something that engine tuners often turn to in order to make their engines perform better or improve reliability. While collets for the general automotive market are very price-sensitive, decisions on the quality of racing collets are not driven purely by the desire to save, say, 0.1 cents per piece. So, where collets for passenger cars are stamped from sheet steel or wire, many of those produced for racing...
Valvetrains are often the key to improving engine performance. Given a free hand, most engine development engineers will strive for ever higher engine speeds as a route to increased power output, if friction can be prevented from overcoming the extra power released by the increase in speed. Before the FIA reined in the Formula One engine suppliers, the engine speeds of the V8s were more than 20,000 rpm and heading for 21,000, which would have put the 2.4 litre engines into the territory...
With the dominance of the four-stroke engine in both the automotive passenger car market and most types of motorsport, there are plenty of opportunities for suppliers of timing gears to improve either on standard equipment or to optimise these components in bespoke engines. With timing gears, what we want often want to do is improve durability while decreasing inertia and component mass. A number of surface treatments can help us achieve these goals. Carburising, also commonly referred to...
In most race engines, much of the heat transfer from the valve to the cooling medium – whether it be oil, water or air – is via the valve seat insert, then into the head and eventually to a fluid that will reject the heat to atmosphere. In the case of the inlet valve, heat flux is only very modest compared to that in an exhaust valve. The inlet valve is kept cool owing to the flow of cool inlet charge over it, and very little heat is rejected to anywhere other than the valve...