Wobble: it's not the most scientific term to emerge from the field of mechanical engineering but it describes perfectly a particularly important event that no other word can. Important because it's the phenomenon that, to a large degree, helps explain the minute variations between the cycles of an IC engine that have bedeviled engineers for years.

Granted, one needs a huge x-ray machine and the world's fifth-largest supercomputer (see Processing power) to witness it in detail, and then calculate and model its effects on the complex and explosive world of an injection-fed combustion chamber, but doing so gives a much clearer understanding of its implications.

Certainly, witnessing the wobble and its consequences was an experience Sibendu Som, principal investigator
A pioneering project that simulates the events that occur inside fuel injectors is providing the key to understanding the causes of engine cycle variation
and mechanical engineer at the Center for Transportation within the US Department of Energy's (DoE) Argonne National Laboratory (ANL), will never forget.

"It was a eureka moment," Som says. He's describing the time, 18 months into ANL's Virtual Engine Research Institute and Fuels Initiative (VERIFI) program, when he and his colleagues observed how the needle valve that permits fuel to pass through the orifices of an injector and into the combustion chamber, moves rapidly and minutely from side to side under pressure.

Read more in Engine Technology International's article, The Missing Link.