|Toyota Optimal Drive 1.33-liter Dual VVT-i gasoline engine with Stop&Start. Click to enlarge.|
Toyota is applying its new 1.33-liter, Dual VVT-i gasoline engine with Stop&Start in the Auris. The engine is also to be applied in the iQ. (Earlier post.) The new 1.33L engine in the Auris delivers a 19% improvement in fuel consumption and a 17% decrease in CO2 emissions compared to the previous 1.4L VVT-i unit.
The new Auris 1.33 Dual VVT-i Stop&Start is being branded as an “Optimal Drive” vehicle. (Earlier post.) Toyota Optimal Drive covers a range of different technologies that can be applied to achieve real-world results in decreasing fuel consumption and emissions without compromising driving pleasure. This approach, Toyota says, is in contrast to “some car manufacturers which have elected to launch special eco-themed models with design, engineering and equipment tweaks to achieve lower emissions and better fuel consumption, often at the cost of comfort and driving pleasure.”
All new Toyota models will benefit from Toyota Optimal Drive, with new iQ, Avensis and Auris 1.33 Stop&Start as the first instances.
The all-new 1.33-liter 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-liter VVT-i and weighs 13kg less. The result is a four-cylinder engine that is the same size as a three-cylinder 1.0-liter 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% 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 suits everyday driving. Output is 100 Nm per liter, with a maximum 132 Nm (97.4 lb-ft) developed at 3,800rpm.
Toyota engineers streamlined the intake channel and used computer simulation to optimize 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 aluminum 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 optimize performance and fuel consumption. This also yields more torque at low engine speeds and helps reduce exhaust emissions.
Auris is the first model in Europe to benefit from Toyota Stop&Start technology. When the car is stationary, with the transmission in neutral and the driver’s foot off the clutch pedal, the engine automatically and quietly stops to reduce fuel consumption and emissions. When the driver re-engages the clutch, the engine automatically restarts. This brings particular benefits in urban traffic, with a potential 15% improvement in the amount of fuel used and CO2 emissions.
Toyota’s Stop&Start system has a permanently engaged starter gear mechanism—the starter motor is in direct contact with the ring gear on the engine, which means the engine stops and starts quickly and quietly. Compared to the 1.4 VVT-i, the start-up noise level has been reduced by 9dB and starting time cut from 0.7 to 0.4 seconds.
The engine is matched to newly developed six-speed manual transmission, with ratios calculated to deliver the best possible balance of performance and fuel economy. The twin-shaft unit is 11% smaller and has 15% fewer components than the five-speed unit, but has a higher torque capacity. Friction is reduced and the driver enjoys an improved gear shift feel. Using an extra gear compared to the transmission used in the previous Auris 1.4, VVT-i, it also gives more refinement at high speed.
From October 2009, the 1.33-liter Dual VVT-i engine will be manufactured at Toyota Motor Manufacturing UK’s (TMUK) factory at Deeside in North Wales. Almost €115 million has been invested in the plant in the past year to prepare for production of the new engine, which comes in addition to the €1.12 billion invested in operations since the factory opened in 1992.
Deeside currently produces 1.4, 1.6 and 1.8-liter VVT-i petrol engines at a rate of about 185,000 units a year. It also undertakes casting and machining of engine sets for export to other Toyota plants around the world. Until Deeside production comes on stream Auris will be fitted with engines manufactured in Japan.
new Auris 1.33 Dual VVT-i vs Auris 1.4 VVT-i
|1.33 Dual VVT-i||1.4 VVT-i|
|Max. power (bhp/DIN hp)||100/101||96/97|
|Max. torque (Nm)||132||130|
combined cycle (L/100km)