Airbus announced a revamp of its twin-aisle A330 passenger jet on Monday, sharpening a contest with Boeing for up to $250 billion of orders at the core of the market as the start of the Farnborough Airshow fueled a debate about new technology. The European planemaker’s decision to add new, more fuel-efficient Rolls-Royce (RR.L) engines to its best-selling long-haul jet comes as it tries to preserve market share against Boeing’s (BA.N) all-new 787 Dreamliner and amid disappointing sales of its own new A350-800 model.