In 2007, the Ford name was removed from the engine pieces as the manufacturer elected not to continue sponsorship of the series. Several other engine changes were made, notably the removal of the calibrated "pop off valve" designed to limit turbo boost pressure, replaced by engine electronics. The rated life of the engine was between rebuilds. Engines were sent by the race teams to Cosworth for the rebuild. In 2007, Champ Car switched to the new Panoz DP01 chassis, which was said to provide better ducting of airflow into the engine. The Champ Car World Series merged into the Indy Racing League IndyCar Series prior to the 2008 season, and Cosworth does not currently provide engines to any American open wheel racing series.