Toyota revamps 1.0L 3-cylinder engine for new AYGO; up to 60 mpg in ECO version
5 March 2014
|New AYGO. Click to enlarge.|
Toyota’s new AYGO, introduced at the Geneva Motor Show, is equipped with an improved version of Toyota’s award-winning 3-cylinder, 1.0-liter VVT-i gasoline engine. Still one of the lightest engines in its class, the unit incorporates numerous revisions that enhance performance and help deliver class-leading fuel efficiency and CO2 emissions.
Gasoline engines are chosen by 85% of A-segment customers in Europe. “We wanted to improve performance, as well as economy. In the A-segment, running costs are paramount—customers don’t want to spend a fortune on fuel bills. But at the same time, we didn’t want to resort to costly technology to reduce consumption, as this would have driven the vehicle price up too much. So our challenge was to come up with relatively simple yet clever ways to achieve our targets,” said David Terai, Chief Engineer of new AYGO.
The combustion character of the 998 cc engine was improved. The compression ratio has been increased from 11.0:1 to 11.5:1. The combustion chamber now benefits from better cooling, and a high tumble intake port ensures an optimal air/fuel mix in the cylinder. The Variable Valve Timing program has also been optimized.
Friction losses were reduced through the adoption of a low-friction timing chain with an auto-tensioner. Diamond-like Carbon (DLC) valve lifters and a twin-tank oil pan further contribute to reduced internal resistance.
What was already one of the lightest engines of its type was made even lighter by fitting a cylinder head with a built-in exhaust manifold.
The engine now develops greater power and torque: 51kW (69 DIN hp) at 6,000 rpm and 95 N·m (70 lb-ft) at 4,300 rpm. 85 N·m 63 lb-ft) of torque is available from as little as 2,000 rpm.
New AYGO comes in both standard and Eco-versions. The latter benefits from a longer 4th and 5th gear, low Rolling Resistance Coefficient.
The standard version achieves a drop in fuel consumption from 4.4 to 4.1 l/100 km (fuel economy of 53.5 mpg US increasing to 57.4 mpg US), which translates into a 7 g/km drop in CO2 emissions to 95 g/km. The Eco unit does even better, with fuel economy of below 3.9 l/100 km (60 mpg US) and CO2 emissions of less than 88 g/km.
Extensive work was also done on the aerodynamics of the car to further enhance efficiency. This includes the optimisation of airflow around the bodywork to reduce air resistance, the use of front and rear spoilers, floor undercovers and rear spats to control the underfloor airflow, and the adoption of a four-way duct to optimize airflow to the engine bay.
As a result, the drag coefficient of new AYGO has been reduced from Cd 0.30 to Cd 0.29, with a further reduction to Cd 0.28 for the Eco variant.
X-shift. The x-shift transmission is available as an option on new AYGO. This improved automated manual transmission has a fully automatic shift mode and no clutch pedal, using computer control to synchronize engine, clutch and transaxle for quick and precise shifting.
The transmission’s gear ratios have been revised for a better balance of driving pleasure and fuel economy.
Selecting E (Easy Mode), M (Manual) or R (Reverse) allows the car to ‘creep’ like a conventional automatic. In E mode, the system selects a suitable gear according to the accelerator pedal, vehicle speed and driving conditions.
New AYGO’s x-shift is equipped with the kick-down function standard to automatic transmissions. Moreover, it is possible to override the system temporarily by using the steering wheel-mounted paddles.
Selecting M mode allows the driver to manually change gear via either the shift lever itself or with the paddle switches.
When equipped with x-shift, new AYGO returns fuel consumption of 4.2 l/100 km (56 mpg US) and generates CO2 emissions of 97 g/km.
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