[CPretenteriS]

BMW is in the early stages of making an all-new, super-efficient, Euro4 compliant water-cooled replacement for its iconic Boxer engine.

The new engine is being developed because of tough Euro4 emissions which come in to force from 2012, and the current air-cooled engine doesn’t meet the new standards.

Air-cooling is a problem for engineers seeking lower emissions and reduced fuel consumption because efficiency is lost not just at higher engine temperatures, but also from cold.

By contrast, a liquid-cooled engine doesn’t get as hot when used hard, but also warms up faster because of the water-jacket’s insulation.

If you can control an engine’s running temperature and keep it within its ideal operating range, it can burn the fuel/air mix more cleanly and efficiently.

Insiders at the Munich development centre let slip to a specialist German BMW magazine that a top-secret project is underway to replace the air-cooled engine that can trace its ancestry back to the first boxer BMW bikes nearly 90 years ago with a new liquid-cooled replacement.