In the July 2010 issue of RET-Monitor, keyword: bearings, I wrote about lead-free bearings and possible engineering concerns surrounding their introduction. Extending the search for the reasons behind why the substitute for leaded bearing materials is not yet embraced by the race engineers led to a short interview with a leading supplier of competition bearing shells. In addition to possible sensitivity issues concerning roundness (shape and steps in the circumference of the bearing bore)...
The complex interaction of components that represents the valvetrain operates in some of the most difficult tribological circumstances. With rapid changes in instantaneous direction between adjacent parts, and high contact stresses, the challenge of maximising the output of the engine while maintaining an acceptable level of reliability has never been more onerous. While it is true that the vast majority of camshaft wear takes place during cold start and warm-up, when the temperature of...
In the recent coatings Focus article in Race Engine Technology (Issue 47, June/July 2010), there was brief mention of thermal dispersion coatings. The aim of these coatings is to eliminate surface 'hot spots' on components and thereby equalise the temperature. Their most common use is on cooling system components, although one supplier we spoke to said one of his customers found success using the coating on aluminium connecting rods, making them less prone to failure. In terms of...
In my previous article on the subject of con rods I asked, "Can we manage without big-end bearings?" and went on to look at the various attempts to do this and the possible future options. The article briefly mentioned the benefits of not having a bearing, and observed that there is one currently successful application of bearing-free technology being raced. In the application concerned - four-stroke, single-cylinder race engines with 'assembled' cranks, where the...
While the main purpose of a crank is obvious, it has many other demands placed upon it. Rotating constantly as it does, it is ideal for taking drives to other assemblies such as pumps. While it is possible to drive pumps electrically - and there are some advantages to doing this - it is banned in some forms of motorsport, and the vast majority of series-production engines drive their pumps mechanically. With very few exceptions, four-stroke engines use camshafts to open poppet valves, and...