Toyota Motor Corporation is developing a series of engines belonging to its ESTEC (Economy with Superior Thermal Efficient Combustion) development concept. Subsequent to the launch of the 2.0-liter DI Turbocharged 8AR-FTS, this paper describes the development of the 8NR-FTS, a 1.2-liter inline 4-cylinder spark ignition downsized turbocharged direct injection (DI) gasoline engine. Following the same basic concepts as the 8AR-FTS engine [1], the 8NR-FTS incorporates various fuel efficient technologies such as a cylinder head with an integrated exhaust manifold, the Atkinson cycle using a centre-spooled variable valve timing with mid-position lock system (VVT-iW), and intensified incylinder turbulence to achieve high-speed combustion. Instead of the D-4ST system that incorporates port and direct injection, the 8NR-FTS emphasizes compactness by adopting the D-4T system that performs only DI in each cylinder. In combination with a single-scroll turbocharger, high torque is achieved from low engine speeds by cooperative control with the VVT system. This engine also adopts a stop and start control strategy that achieves speedy and shock-free re-start performance by starting the engine with stratified injection in the first compressed cylinder. The engine can be mated with either a 6-speed manual transmission (6MT) or continuously variable transmission (CVT). Especially with the CVT, turbocharger lag duration is reduced by shifting control, and both fun-to-drive dynamic performance and excellent fuel economy of 10% better than a naturally aspirated (NA) 1.8-liter engine can be realized by switching between normal and sport driving modes.
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