As can be seen from earlier articles in RET-Monitor on race engine block material, a trend can be seen towards Compacted Graphite Iron as a crankcase material. It has been used occasionally in the past on highly loaded motorsport applications but it now seems to have become more widespread. The reasons for this are the higher mechanical strength of the material in relation to increasing combustion loads, and a broader availability of CGI combined with the ability to cast thin-wall...
Last time we looked at ways of producing high-quality cylinder bores. Needless to say, the thinking and methods used might seem extreme to some or insufficient to others. In all this, however, we must always remember that it is not the shape or degree of roundness of the bore that is necessarily important but the degree to which the piston can conform and seal the combustion gases that is perhaps more critical. We can make the bore as circular in cross-section as possible but unless the...
If a shaft spinning at 20,000 rpm can pose a sealing problem then what about one doing 120,000 rpm or even, dare I say it, 240,000 rpm? A simple enough question, you might say, but before answering it we need to understand the application and the desired effectiveness of the seal required. A crankshaft oil seal for instance needs to be 100% reliable under all conditions. This is because in the mind of the customer, it takes but a single drop of oil to constitute a failure. In the case of a...
At the recent Monza World Superbike round, I asked Marcus Eschenbacher, crew chief to Cal Crutchlow at Sterilgarda Yamaha, about their choice of exhaust configuration. As many who work in Formula One or study it will know, the exhaust systems on each side of the engine are arranged in a 'four-into-one' collector with four primary pipes coming together in a single collector on each side. The arrangement is often abbreviated to '4-1', denoting four pipes converging into one...
We have, in previous articles, looked at the importance of correct pre-load for fasteners, and this is especially important where there are cyclic loads involved that might causes fatigue failures. One of the more reliable ways in which we can tighten a fastener is to measure the extension or 'stretch' of a given bolt or stud, and for a con rod, this is indeed the way that the vast majority of engine builders will work. Knowing the load versus extension relationship of the bolt means...