What happened to the turbocharged engines?
They were banned by the new-car rules in January 1997. There were several reasons for this: • Elimination of the expensive turbocharger and its control systems. • Control of horsepower and speeds. • Improved engine reliability and reduced costs. • Elimination of the need for the troublesome and controversial pop-off valves, which were used to enforce limits on turbo boost, but often malfunctioned and caused engine failures and numerous allegations of cheating. (NASCAR fans can draw a comparison to the NASCAR restrictor plates.) • Something to distinguish the IRL cars from CART. Also, it should be noted that the elimination of the turbochargers was part of a larger strategy of moving away from pure-race engines to engines based on production blocks and heads; see question 4.1. As of the 2000 season, the IRL will be abandoning the requirement for engines to be based on production blocks, but despite this it is very unlikely that the turbos will ever return.
