Getting valve springs to live in a World of Outlaws sprint car engine - one that is 408-410 cu in and makes 850 hp (with more than 700 lb-ft torque at 6300 rpm) - is one of engine building's black arts. At Shaver Specialties Racing Engines (SSRE) in Torrance, California, the challenge is to overcome the "voodoo of valve spring breakage," according to Dennis Hardesty, right-hand man to owner Ron Shaver. "For the past year-and-a-half, the majority of our racing valve...
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...
When thinking of a topic about 'pushrods', one might think on the specifics of the pushrod as a component. Another is to think of the way valvetrain systems have developed over time, from the low in-block camshaft and pushrod-actuated side valve systems to the current four double-overhead camshaft systems, and everything in between. Looking for a typical example of such an evolution, my interest was awakened in the BMW approach with its boxer motorcycle valvetrain systems, where...
Known as 'The Professor' for his meticulous preparation and dedication to technological upgrades to his National Hot Rod Association (NHRA) engines, Warren Johnson continues to move forward in his quest to tune the best possible GM DRCE3 Pro Stock engine. Johnson figures he's been working with this particular set-up for the past five years, and cites valve spring life as one of the larger challenges he faces on the 23-race tour. "The revs on these engines has gone up, and...
In previous articles we have looked at the various materials used for valves, and examined some of the relative merits of these materials. The 'super-alloy' materials are particularly suited to high-temperature applications, having been developed initially with a view to use in gas-turbine engines. But they are relatively heavy. Titanium is much more favourable in terms of component mass, and is widely used in motor racing. The material comes with problems though; titanium requires...