BMW N45

The BMW N45 was a naturally aspirated four-cylinder petrol engine produced from 2004 to 2011 that replaced the N40, built alongside the N46 and sold only in countries where vehicle taxes favoured small displacement. It is based on the N46 but has no balance shafts and no Valvetronic variable valve lift, while keeping double-VANOS variable valve timing, and a 2007 update was called the N45N. The direct-injected N43 was introduced in 2007 as its successor but could not be sold where fuel is high in sulfur, so the N45 continued until the turbocharged N13 arrived with new generation vehicles. The N45B16 powered the E81 and E87 116i and the E90 and E91 316i. The N45B20S, enlarged to 1,997 cc with double overhead camshafts and sixteen valves, homologated the limited-production E90 320si for the World Touring Car Championship, chosen over the N46 because the lack of variable valve lift allows higher engine speeds.