GM’s new 3.6-liter direct-injection V6 engine, debuting in the 2008 Cadillac CTS, features a unique patent-pending injection system that is isolated from the cylinder head, resulting in improved noise, vibration and harshness characteristics that reduce overall noise levels to those compared to a port-fuel injected engine. The injectors, which inject fuel at pressures as high as 12 megapascals, are housed in an isolation cuff made of stainless steel which acts like a spring, absorbing energy created by the pulsing of the injectors as they deliver fuel into the cylinders. “The cuff separates the injector from the cylinder head, which results in a less harsh ticking sound that you hear outside the vehicle. It is on all six injectors and it has been one of the biggest hurdles we have been working on since we started the development of the DI system,” said Jeff Mantey, design engineer-duel delivery systems at GM’s Powertrain division.— KMK