The New Toyota V12 Gasoline Engine
The newly developed 5.0-liter V12 engine installed standard in the remodeled Century represents Toyota's latest advances in gasoline engine technology. Combined with other advanced powertrain components, the finely crafted BEAM S* 1GZ-FE's performance characteristics are ideally suited for Toyota's flag ship luxury vehicle, providing smooth power across the rpm band while boasti ng impressive fuel economy.
Characteristics
Shortening of the interval between combustion cycles in each cylinder minimizes torque variation. Combined with the slant-squish combustion chambers, iridium electrode spark plugs, and Variable Valve Timing-intelligent (VVT-i), this stabilizes combustion and enables smooth engine operation like that fo und in electric motors.
Increased rigidity of moving and structural components, such as pistons and the cylinder block, decreases vibration by about 10% over the Celsior's (Lexus LS400) 4.0-liter V8 engine (1UZ-FE), which itself is renowned for its quietness.
Working in tandem with the VVT-i, a variable intake system alternates between two set intake levels, providing excellent torque in the low- to mid-range, which is most common during daily driving.
Compact combustion chambers provide a high compression ratio (10 · 5:1). VVT-I reduces intake loss, while titanium coated shims and a newly developed, low viscosity engine oil minimize friction loss. Along with the engine's ability to stabilize combustion when under a light load and to operate at very low rpms while idling, these increase the new Century's fuel efficiency by 13% over the previous model to 7.2 km/liter (10 · 15 mode).
*Breakthrough Engine with Advanced Mechanism System
Machining of engine components and engine assembly are performed by skilled technicians on production lines dedicated to the 1GZ-FE, while specialists carefully conduct final engine inspection using stethoscopes. Feedback from intensive durability testing of individual components was vital to the R&D p rocess. The fail-safe system, in which the two six-cylinder banks each have fully dedicated operating systems, further guarantees the dependability of this marvelous system.
Technologies
Slant-Squish Combustion Chambers
The squish area (the small niche formed between the piston and the cylinder head) is aligned with the wall of the combustion chamber so that the flame can quickly spread to the edge of the combustion chamber, improving combustion efficiency. Also, the openings around the intake valves have been widened, providing for greater amounts of air to be taken in and raising torque.
Mass Production of Iridium Electrode Spark Plugs a World First
Iridium increases the longevity of the center electrode, allowing for a smaller electrode diameter (0.7mm) and better ignition, thus stabilizing combustion.
VVT-I
Continuously controlling valve timing to best suit driving conditions increases torque, output, and fuel efficiency, while also reducing NOX and HC emissions.
Titanium-Coated Shims
The valve lifter shim surface that contacts the cams is mirror-finished and then hardened significantly with a titanium nitride coating. Moreover, the coating's microscopic protrusions further polish the surfaces of the cams that they come into contact with. This results in unsurpassed smoothness between all contact surfaces, reducing wear and rotational resistance with the camshaft.
Electronic Throttle Control System-intelligent (ETCS-i)
Computer signals electronically control the throttle valve in response to accelerator pedal movement. This control provides even torque even when the accelerator is pushed rapidly, smoothing the Century's progress.
Electronically Controlled Hydraulic Cooling Fan
In order to reduce engine cooling fan noise, the fan is controlled electroni cally to avoid its rotation rate from moving in stages and to operate it at the minimum speed necessary to cool the engine.
Cylinder Block and Oil Pan Rigidity
Toyota engineers used the latest computer technology to study the strength and rigidity of moving and structural parts, and sought the ideal engine layout through measurement and analysis of component movement, as well as their angles and positioning. The seam between the oil pan and the cylinder block, which is crucial for controlling vibration, is slightly bell-shaped. With in the cylinder block itself, internal parts are joined by bridge-type ribs, while the left and right sides are also connected, thus increasing bending and twisting rigidity, providing unsurpassed quietness.
Fail-Safe, Independently Controlled Cylinder Banks
Intake systems components such as air cleaners, electronic throttles, and surge tanks, as well the sensors and control units necessary to operate fuel injectors and ignition, are located independently in both the right and left six-cylinder banks. This fail-safe system is equivalent in ability to that of an airplane, allowing for the engine to continue operating even if the vital electronic control system of one cylinder bank should break down.
KEY SPECIFICATIONS OF THE BEAMS 1GZ-FE ENGINE
Total displacement (cc) 4,996 Valves DOHC 4-valve; chain and gear drive
Number of cylinders 60degree V12 Maximum output (PS/rpm) 280/5,200 net
Bore x stroke (mm) 81.0 x 80.8 Maximum torque (kg-m/rpm) 49.0/4,000 net
Combustion chamber Pent roof type Fuel supply system Electronic Fuel Injection (EFI)
Compression ratio 10.5:1 10 - 15-mode fuel
consumption (km/l) 7.2