The all-new 1.33-litre Dual VVT-i engine represents the latest in Toyota lightweight powertrain technology. Benefiting from Toyota's motorsport experience, where compact and powerful engine design is crucial, the new unit is 54mm shorter and 127mm narrower than the previous 1.4-litre VVT-i and weights 13kg less. The result is a four-cylinder engine that is the same size as a three-cylinder 1.0-litre VVT-i. Its small bore and long stroke design gives a narrow block and reduces weight to give a very high power-to-weight ratio.
New pistons were developed with a smaller contact area to help produce quick and efficient combustion. Piston weight was also significantly reduced, from 280g to 180g - a 36 per cent saving - which means they use less energy. For leaner combustion, an oil jet was integrated into the design.
The new engine gives a solid torque curve that is ideal for everyday driving. Meticulous engineering has brought an output of 100Nm per litre, with a maximum 132Nm developed at 3,800rpm.
Toyota engineers streamlined the intake channel and used computer simulation to optimise airflow. Surfaces were made smooth and any angles or sharp edges were rounded off to help reduce turbulence.
More weight has been saved by using a cylinder head cover and resin intake manifold. In addition, the highly rigid aluminium crankcase is connected to the transaxle casing, improving rigidity of the joint in the powertrain and thus reducing noise and vibration. An all-new camshaft profile was designed, reducing weight and friction.
Dual VVT-i (variable valve timing - intelligent) provides continuous, variable control of both the intake and exhaust valves to optimise performance and fuel consumption. This also yields more torque at low engine speeds and helps reduce exhaust emissions.Published 19 November 2008