For all its apparent simplicity, your typical piston ring is a complex device. Required to seal against combustion gases on the power stroke and yet minimise friction on the upstroke, under all conditions of speeds and loads, the task might seem possible if we include the additional demand that all this and more should be achieved with the minimum of weight. It is perhaps little wonder therefore that under the high-speed dynamic loads experienced, rings tend to move in ways not originally...
In the pages of Race Engine Technology and in these short web articles, there have been numerous mentions of the significant benefits of having residual compressive stresses present at the surface of a component. To recap, incorporating a method (or methods) of introducing residual compressive stress at a component's surface is, in general, likely to improve the endurance limit of a component loaded in bending or torsion. Given that there are very few components that are loaded in a...
In the past, most engine development work would take place on passive dynamometers, which allowed only for steady-state power runs to ascertain basic power and torque curves. The advent of computer-controlled 'active' dynos however has revolutionised the way engine development programmes are run, presenting engineers with a plethora of new tools to understand engine characteristics. A passive dyno usually consists of a power absorber - a water brake, hydraulic brake or eddy current...
Le Mans places abnormal demands on almost every component in a racecar, with the suspension and engine taking a relentless pounding on every lap of the 13.629 km circuit. Also subject to the same war of attrition is the gearbox and driveline. In the past, gearboxes were a regular source of problems for competitors, either thanks to simple fatigue failures of parts, or driver fatigue leading to missed gearshifts. In recent years, transmission problems have become far less commonplace; this...
The pushrod, or overhead valve (OHV), engine has a lot to recommend it in terms of packaging, although it achieves this at the expense of much valvetrain stiffness compared to an overhead cam (OHC) mechanism. One of the least stiff members in the pushrod valvetrain is the pushrod itself. Owing mainly to space constraints, but also possibly to mass targets in a smaller regard, the pushrod is a long slender component whose stiffness can dominate the dynamic behaviour of the whole valvetrain...