Automotive Valve Wear

Dr. Roger Lewis 

Dr. Tom Slatter

In March 2007 the EU Heads of State set a series of demanding climate and energy targets, which included a pledge to reduce EU greenhouse gas emissions to at least 20% below 1990 levels. This has led to a reduction of the amount of oil being used in the air streams of automotive diesel engines.

Unfortunately, the less oil used, the greater the friction and the greater the wear on the engine valves as they oscillate on their seat inserts. Increased wear can lead to leakage, creating a less efficient engine, reducing engine life and somewhat ironically, creating higher exhaust emissions.

By using a specially developed impact wear rig and valve testing rig, we are able to simulate the wear of both inlet valves and seat inserts used in diesel engines. The results have been used to develop RECESS, a computer code that can predict how valves will wear, based on factors such as their composition, speed, shape and position in the engine. It is also capable of recommending modifications to their properties, in order to produce the most efficient valves possible.

The drive to reduce carbon emissions is an ambitious target, which will be met by making adjustments on a minute but no less significant level.