The new lexus gs 2012: engines and transmissions
• GS 450h with second generation Lexus Hybrid Drive system
• New Atkinson cycle V6 petrol engine with next generation D-4S direct injection technology
• Over 23% reduction in fuel consumption to 5.9l/100km and CO2 emissions now 137g/km
• Revised GS 350AWD powertrain with more power and improved efficiency
• New GS 250 available for the first time
In Europe, the new GS model range is available with a choice of three powertrains ; the GS 450h full hybrid, featuring a second generation Lexus Hybrid Drive system; a revised GS 350AWD, with increased power and greater efficiency; and the GS 250, featuring a 2.5 litre V6 which is new to the GS model range.
Reinforcing the company's commitment to the future of full hybrid drive technology, the new GS 450h is equipped with a second generation Lexus Hybrid Drive system.
Incorporating comprehensive improvements to every aspect of its full hybrid powertrain, the new GS 450h offers significant reductions in fuel consumption and CO2, NOx and PM emissions, with no loss of performance.
With a total system power output of 254kW/345DIN hp, the GS 450h will accelerate from 0-100km/h in 5.9 seconds and has a maximum speed of 250km/h. Conversely, fuel consumption has been reduced by 23% to 5.9l/100 km, and CO2 emissions have fallen to 137g/km.
Lexus Hybrid Drive System Architecture
As with every Lexus hybrid vehicle, the new GS 450h is a full hybrid capable of operating in petrol or electric modes alone, as well as a combination of both. Its Lexus Hybrid Drive system features an ultra-smooth running, 213kW/290DIN hp, 3.5 litre V6 petrol engine mated to a compact, high-output, water-cooled permanent magnet electric motor, the two powerplants driving the rear wheels both independently and in tandem, as appropriate.
In addition to the petrol engine and electric motor, the new GS 450h's hybrid drive system further comprises a generator, a high-performance nickel-metal hydride battery, a power split device which, via planetary reduction gears, combines and re-allocates power from the engine, electric motor and generator according to operational requirements, and a compact power control unit to govern the high speed interaction of the system components.
3.5 Litre Atkinson cycle V6
Adapted specifically for the hybrid powertrain, the 3.5 litre, DOHC, V6 petrol engine benefits from several technical improvements. It adopts the Atkinson cycle to optimise the fuel-efficient benefits of Lexus Hybrid Drive.
With conventional four-cycle petrol engines, there are times when 'fuel enrichment' becomes necessary, cooling exhaust gases to prevent degradation or destruction of the catalytic converters. Because the intake valves close late in an Atkinson cycle engine, compression is delayed. This creates a high expansion ratio for less compression, reducing intake and exhaust energy losses and converting combustion energy to engine power more effectively. As a result, the exhaust temperature is lower than that of conventional engines.
Further reductions in fuel consumption have been achieved through a high physical compression ratio of 13:1, a new, mid-port intake tumble generator and the adoption of next generation D-4S direct injection technology.
D-4S is the latest evolution of Lexus' stoichiometric, 4-stroke, direct injection technology. With one injector installed in the combustion chamber and a second mounted in the intake port, it combines the strengths of both direct and port injection, realising optimum engine efficiency throughout the power band and improving torque across the rev range, whilst minimising fuel consumption and emissions.
The new GS 450h's next generation D-4S system features new slit-type injector nozzles with a modified port shape, a higher fuel pressure for more efficient combustion, and idle port injection for improved NHV characteristics.
Engine noise, vibration and friction has been lowered through the adoption of lightweight chain technology, a piston pin offset change and a reduction in the number of drive belt reinforcement ribs.
In addition, engine durability has been improved through the removal of all external oil lines, and environmental performance enhanced by a new-specification catalyst which contains greatly reduced levels of precious metal.
Additional Hybrid System Component Improvements
The cooling performance of the hybrid system's Power Control Unit (PCU) has been improved through the adoption of dual cooling paths and a single-piece, integrated DC/DC converter.
System control has been enhanced. The PCU boosts motor drive voltage to a maximum 650V in SPORT S mode and limiting it to a maximum of 500V in ECO mode to provide a more environmentally—friendly driving performance.
The electric motor features lighter mounts and a reduction in friction. And the system's regenerative braking operation range has been expanded, contribution to further improvements in fuel efficiency.
In addition, the battery layout has been redesigned; a new stacked configuration maximising luggage space.
Expanding the powertrain line-up to offer further improvements in fuel economy and emissions, a 2.5 litre V6 petrol engine is available for the first time in the Lexus GS model range.
The V6 features D-4S direct injection, and Dual VVT-i (Variable Valve Timing-intelligent) to both intake and exhaust camshafts, enhancing engine performance.
It develops 154 kW/209 DIN hp at 6,400rpm and 253Nm of torque at 4,800rpm, accelerating the GS 250 from 0-100km/h in 8.6 seconds and giving a maximum speed of 230km/h. Fuel consumption is 8.9l/100 km, and CO2 emissions 207g/km.
The new 2.5 litre V6 is mated to Lexus' '6 Super ECT' close-ratio 6-speed automatic transmission, which features a sequential manual shifting mode. As with the 3.5 litre engine, it incorporates numerous technologies including faster shift speeds, earlier torque converter lock-up and downshift throttle blips- to support the range of driving modes available through the Drive Mode Select system.
The 3.5 litre V6 petrol engine of the new GS 350AWD has been revised to lower both fuel consumption and emissions.
The advanced V6 features D-4S direct and port injection, and Dual VVT-i (Variable Valve Timing-intelligent) to both intake and exhaust camshafts, significantly enhancing engine performance and reducing fuel consumption.
It develops 233 kW/317 DIN hp at 6,400rpm and 378Nm of torque at 4,800rpm, accelerating the GS 350AWD from 0-100km/h in 6.3 seconds and on to a maximum speed of 190km/h. Fuel consumption has been reduced to 10.2 l/100 km, and CO2 emissions are 237g/km.
The '6 Super ECT' close-ratio 6-speed automatic transmission features a sequential manual shifting mode. It incorporates numerous technologies including faster shift speeds, earlier torque converter lock-up and downshift throttle blips- to support the range of driving modes available through the Drive Mode Select system.
The GS 350AWD's electronically controlled all-wheel drive system is designed to improve traction and grip by automatically varying front-to-rear torque balance from 50:50 to as much as 20:80, providing exceptional stability under all driving conditions.