In racing valvetrains, there is always an imperative to reduce reciprocating mass, as it allows the valvetrain engineer to be more aggressive with his cam profiles in an attempt to improve the valve lift curve, by increasing lift, increasing the area under the curve and so on. This will generally require greater valve acceleration or deceleration.If we are constrained to using the existing valve design, we may be able to cope with increased forces and stresses due to increased...
While pushrods may not have a place in (relatively) unrestricted, top-flight racing engines any more, they are still a part of the racing landscape in many forms of racing, whether by regulation or through financial expediency.NASCAR, of course, mandates the use of a pushrod engine in all its racing series, along with a single block-mounted camshaft and a controlled height above the crankshaft. Like almost every part of a racing engine, pushrod design is the subject of a number of opposing...
If a valve spring for a race engine is to survive a service life of 1400 race miles or 1600 absolute miles then it needs to be robust and reliable. In the Indy Racing League's IZOD IndyCar Series, where the Honda Indy V8 is the sole motive power, Honda Performance Development (HPD) has gone with a steel, flat-top, double-valve spring without insert, to achieve the balance needed on road courses, street circuits, short ovals, speedways and superspeedways. HPD has tried different designs...
In the previous article on this subject we looked at the use of Inconel as a valve material. This month I'll look at an application of another high-temperature valve material, Nimonic alloys.These are nickel-based alloys which, similar to Inconel materials, maintain a high proportion of their room-temperature strengths at elevated temperatures. As with Inconel alloys they are commonly used in turbocharged or supercharged applications, where the high operatingtemperatures in these...
A strong and stable valvetrain is essential to power an NHRA Full Throttle Drag Racing Series Top Fuel rail down the 1000-foot dragstrip. For that reason, teams are always looking to improve stability of the pushrod. For a long time, Kenny Bernstein Racing used only hollow pushrods - and purchased those exclusively from Manton Pushrods in Lake Elsinore, California. While the Top Fuel team continues to work with Terry Manton for its pushrods, the specification has changed. "We've...