Most of the articles I've written about valves have looked at the design of, or materials in, conventional poppet valves as applied to many four-stroke engines. So I thought it would be good to take a brief diversion from this and look at something completely different. Two-stroke engines have been used widely for grand prix motorcycle racing (although this era is soon to come to an end), motocross, snowmobiles, jet skis and so on, and are currently enjoying something of a resurgence...
It is a fact that development of titanium alloys is driven by the substantial needs of the aerospace industry, for improved properties or lower costs. The use of titanium is widespread in aircraft, both military and commercial, and with great emphasis being placed on reducing mass, the development of better alloys allows parts currently made in titanium to be even lighter or for steel parts to be replaced with titanium. The development and use of surface engineering processes goes hand in...
The previous article on the subject of KERS was a retrospective look at the hybrid system in the Panoz Q9. In seeking to bring the emerging technology of regenerative braking to racing, Don Panoz was years ahead of the game. There are now very few large car-makers who don't have a serious hybrid development programme, and a growing number of them feel the technology is mature enough to release series production models - notably Honda with the Insight and the Civic Hybrid, and Toyota...
In previous articles about the differences between leaded and lead-free bearing shell materials, several reservations about the latter have been discussed, one of which is the heat transport from oil through the bearing shell to the crankcase, where leaded bearings are said to have the advantage. In this article, I want to offer further insight into the temperature differences between the two materials. The data here is to be read as relative between the two materials: due to the...
The surface of a camshaft or its associated follower can fail in a number of ways. Adhesive wear leading to abrasive wear, and corrosive wear, are perhaps the most common but another type of wear - surface fatigue - is sometimes perhaps harder to understand. Adhesive/abrasive wear tend to be lubricant-based issues. Poor lubrication or an incorrectly specified lubricant - it amounts to the same thing - will cause the oil film to break down under extreme loads, producing metal-to-metal...