Exclusive - Emissions crackdown exposes Renault-Nissan engine trouble

By Laurence Frost and Gilles Guillaume PARIS (Reuters) - The Renault-Nissan alliance is replacing its top executive in charge of combining the carmakers' engines and gearboxes, sources told Reuters, as tightening emissions regulations expose the slow pace of integration so far. Alain Raposo, global head of powertrain engineering, will be moved to an advisory role, and a successor announced this week, four people with knowledge of the matter said. A Renault-Nissan spokeswoman said there would be