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Friday, April 1, 2011
The 2AZ-FE engine, standard across the Camry grade lineup (and now used in the Toyota Corolla), is based on the 2.4-liter four-cylinder engine from last year, but is substantially upgraded. This redesign employs optimized intake and exhaust systems, as well as strategies that reduce internal friction and enhance engine-block/crankcase rigidity. The result is improved power output with exceptional fuel economy and reduced noise and vibration levels.
This engine is based on bore/stroke dimensions of 3.48 x 3.78 inches (88.5 x 96mm) for a displacement of 2,362 cc, or 144.1 ci, and develops 158 SAE horsepower. During their revision of the existing engine, engineers boosted the compression ratio slightly to 9.8:1, altered the cam profile and paid particular attention to reducing friction through strategies such as reducing the tension of the piston rings while increasing their tensile strength. Finally, they reduced piston weight, optimized the balance shaft, improved sound insulation performance of the engine cover and improved the engine mounts. With this engine, Camry buyers have the choice of either five-speed manual or electronically operated five-speed automatic transmission.
For those looking for more power, the new 2GR-FE engine – a 24-valve, DOHC 3.5L V6 - is available in the LE, SE and XLE. This engine is designed to deliver up to 40 percent better acceleration over the 2006 model year Camry 3.3-liter V6. The V6 is based on bore/stroke measurements of 3.70 x 3.27 inches (94.0 x 83.0 mm) for a displacement of 210.9 ci, or 3,459cc, and uses a compression ratio of 10.8:1 to generate 268 SAE horsepower. The dual camshafts, which are chain-driven, employ Dual Variable Valve Timing with intelligence (Dual VVT-i) for optimal cam timing – and therefore maximum power production - at all RPM levels.
Engineers improved airflow through every element of the engine’s intake tract. This includes improving air-cleaner shapes, intake ducts and the intake manifold and cylinder head intake ports. In addition, valve openings were enlarged and exhaust pressure loss was reduced from the exhaust manifold to the muffler. Engineers modified the shape of the Camry’s taper-squish combustion chambers to make maximum use of that air. And they provided exhaust manifolds that incorporate catalytic converters for greater efficiency.
Harnessing this engine’s output is an all-new six-speed automatic transmission that uses 21 percent fewer parts than the conventional five-speed automatic transmission it replaces. This new transmission, which can be shifted sequentially, relies upon a newly developed gear train that uses a Ravigneaux-type compound planetary gear for reduced size, weight and friction.
This new transmission also uses a quick-response, low-friction clutch pack for enhanced fuel economy; an ultra-flat, low-inertia torque converter for high transmission efficiency; a set of high-response, low-slip clutch packs and new electronic and hydraulic control systems that incorporate an intelligent shift control that learns driver’s driving style and selects gears based on that style.
Labels: Toyota Cars
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