Engine
Since its inception, the Lancer Evolution series of vehicles has relied on the proven 2.0-liter inline four-cylinder 16-valve DOHC intercooler-turbocharged 4G63 engine. The ninth edition of this race-bred vehicle is powered by the most technologically advanced production version of this engine to date.
The Lancer Evolution is the first vehicle in the series to feature MIVEC (Mitsubishi Innovative Valve timing and Electronic Control). The Lancer Evolution's MIVEC system operates on the intake camshaft, helping to optimize the engine's valve timing to optimize the combustion in all running conditions. This technology results in more torque and horsepower while improving fuel economy across the entire rev range. The improved breathing afforded by this valve train enhancement moves the engine's redline to 7000 rpm.
The MIVEC system can alter the intake camshaft sprocket's phase angle to retard the timing of the closure of the intake valves at higher rpm. This valve event timing creates more power because of the more efficient and complete filling of the combustion chamber thanks to the intake charge's inertia effect. Meanwhile at lower rpm, the MIVEC system will retard the timing of the opening of the intake valves to decrease intake/exhaust overlap timing, helping promote more stable combustion, while reducing fuel consumption and emissions.
The Lancer Evolution's MIVEC system uses the engine's oil pressure to engage movement of the intake camshaft's front sprocket. As the camshaft control signals are received from the ECM, a spool valve at the oil control valve moves the sprocket toward the advance or retard side depending on the ECM signal. As the intake camshaft's actual and target sprocket angles meet, the oil pressure in the advance and the retard chambers is held to maintain the phase angle of the camshaft. The MIVEC system's oil control valve is a closed loop system so that the actual and target phase angels are identical.
The Lancer Evolution 's 4G63 engine is also fed intercooled air by an updated turbocharger that is more responsive than previous designs, achieving 5 percent faster boost. The shape of the TD05HR-16G6C-10.5T turbocharger's compressor cover has been enhanced to optimize responsiveness and durability. The result is more torque in the 1800-5000 rpm range, as well as higher output from the peak output speed of 6500 rpm all the way to the 7000 rpm limit. The turbocharger's wastegate valve is now more circular in shape, and lighter in weight. Turbo boost is 139kPA (20psi) at 3500 rpm and 111 kPA (16 psi) at 6500 rpm. The 2.0-liter power plant generates class-leading torque of 289 lb-ft at 3500 rpm, and 286 horsepower at 6500 rpm.
Several mechanical revisions help the Lancer Evolution attain its level of performance and improve durability. The use of MIVEC system on the engine necessitated a revised cylinder head casting. The casting's cooling passages have been revised for improved durability and the tempering process was also improved. The cylinder head uses longer-reach sparkplugs that help control combustion chamber temperatures. A five-layer metal head gasket design with revised coolant passage holes replaces the three-layer metal unit to better withstand the engine's elevated, forced induction fed cylinder pressures. The pistons in the Lancer Evolution are made of a stronger alloy and are sealed to the cylinder wall using a more efficient two-piece ring package, replacing the previous three-piece ringset. This revised ring arrangement helps reduce the engine's oil consumption by 10 percent. A new bell housing cover made of a vibration dampening steel was employed to help reduce exterior noise. A new design cast magnesium valve cover highlighting the engine's MIVEC feature is also new for 2006. A revised fuel pump with 7 percent higher capacity also appears in the Lancer Evolution along with a redesigned muffler that enhances the exhaust note at low to mid-range engine speeds.
Enhanced Five-Speed And Mr S-Speed Manual Transmission
The five-speed transmission found in the Lancer Evolution RS and has been upgraded with more closely spaced gears, with the fifth gear changed to a 0.761 ratio from a 0.721 ratio. Meanwhile first through fourth gear are more closely spaced than in previous model years' five-speed. The five-speed transmission has a 4.529 final drive ratio.
The s-speed transmission in the Lancer Evolution MR is designed to handle high-torque capacity while providing quick, smooth shifts. The W6MAA gearbox makes use of its additional ratio to maximize the engine's potential in each and every gear.
The close-ratio gearbox employs low-friction Teflon-lined shift control cables to create a positive shift feeling with easier engagement. A shift stroke stopper was combined with the shift lever to provide a precise feel for a completed shift and a pull-ring mechanism helps to prevent accidental shifting into reverse.
The clutch also was revised. A wide-angle damper was adopted to match the increased operating gears in the s-speed transmission and helps to reduce vibration noise.
Lancer Evolution MR vehicles use a 4.583 final drive ratio. The s-speed manual transmission is standard equipment on the Evolution MR and is not available on other Lancer Evolutions.
Body
The Lancer Evolution RS and MR were the first steel monocoque-bodied Japanese production cars with an aluminum roof panel. The use of aluminum reduces the upper body weight by approximately 8.8 lbs (4 kg), which in turn lowers the center of gravity and reduces the roll moment, helping to improve handling performance. With the new roof, the Evolution's center of gravity was lowered by 3 mm. By comparison, to achieve the equivalent center of gravity, a conventional steel roof would have to be lowered 50 mm.
To join the steel frame and aluminum roof panel, Mitsubishi employed an innovative manufacturing method that makes use of self-piercing rivets - which expand radially into the steel of the structural member below - and structural adhesive.
A single longitudinal design bead in the roof panel solves the problem of thermal warping that would normally occur in the manufacturing process due to aluminum's thermal expansion coefficient, which is nearly twice that of steel. For increased cabin strength, diagonal braces reinforce the roof joints at the front, center and rear pillars.
Active Center Differential
First employed on the Japanese-market Evolution VII, Mitsubishi's Active Center Differential (ACD) made its North American debut in Lancer Evolution VIII MR, and is standard equipment on all Lancer Evolutions. Combined with a front helical limited slip differential, the ACD helps raise the Evo's dynamic handling performance to a new level.
The ACD uses a center differential to split torque up to 50:50 between the front and rear wheels using an electronically controlled hydraulic multi-plate clutch. An ECU optimizes clutch cover clamp load for different driving conditions, regulating the differential limiting action between a free state (where torque is split equally between front and rear wheels) and locked states according to driving conditions. The result is better steering response and better traction. From a switch on the dash, the driver may select between three ACD modes - Tarmac, Gravel, and Snow - for response to changes in road surfaces.
The ACD computer receives data from various sensors to calculate the limited-slip torque suitable for a variety of conditions. For instance, steering wheel angle, throttle opening, wheel speeds, and longitudinal and lateral movements of the vehicle are constantly measured to determine the vehicle's path of travel, which helps to determine whether limited-slip torque should increase or decrease at any given time.
The viscous coupling unit (VCU) limited-slip mechanism from the Lancer Evolution's center differential has been replaced by a hydraulic multi-plate clutch in the Evolution MR. The maximum limited-slip torque of the multi-plate clutch is about three times that of a conventional VCU. The hydraulic unit housed in the engine compartment regulates the hydraulic pressure of the multi-plate clutch within the range of 0 to 145 psi.
Front And Rear Limited-Slip Differentials
With the adoption of the ACD, the front differential is changed from an open differential to a helical limited-slip differential. The helical-type limited slip differential provides better durability and higher performance when it's needed most - while steering. Unlike an open differential, which shifts power to the wheel with less grip, the helical limited-slip constantly shifts the bias toward the wheel that has more traction.
Under straight-line acceleration, power remains evenly split between the front wheels. While cornering (e.g., accelerating out of a turn), the helical LSD directs power away from the inside wheel and toward the outside wheel, allowing the driver to begin accelerating earlier and exit the turn at a higher speed, without losing traction.
All Lancer Evolution models use a reliable, mechanical, plate-style, 1.5-way limited slip differential at the rear. This unit's effective design has proven itself in competition providing traction and durability.
Sports-ABS
Sports Antilock Braking System (S-ABS) is standard on Lancer Evolution IXs and MRs. The ECU uses information from a steering wheel sensor that detects steering inputs as well as lateral G and vehicle speed sensors to apportion pressure to each of the four wheels independently. The result is improved steering response while braking.
Sports-ABS has undergone detail tuning for dry tarmac and other high-friction surfaces and now slows the vehicle faster even on an undulating surface. Mitsubishi's Electronic Brake force Distribution (EBD) system, an integral part of Sports-ABS, optimizes allocation of braking force between the front and rear wheels. Increasing the pressure applied to the rear wheels when braking close to the limit, EBD reduces the load acting on the front wheels for better anti-fade performance. The system also compensates for changes in surface and vehicle load conditions to ensure predictable and consistent stopping performance at all times.
MR: Iproved Handling Stability, Ride Comfort
The Lancer Evolution MR inherits the highly acclaimed suspension of the Lancer Evolution while adding several improvements of its own. For a suspension system to achieve the highest levels of all-wheel control, it must keep the tires on the pavement. To improve the MacPherson strut front and multi-link rear suspension, Mitsubishi turned to Bilstein(R), renowned for their high-performance, superior-response shock absorbers. Working together, engineers created a shock absorber designed exclusively for the MR.
Bilstein(R) shock absorbers feature quick responses, as they are capable of switching instantly from the compression to extension process. By lowering the damping force generated by the shock absorbers, grip on the road has improved along with ride comfort. Quicker response time increases: high speed handling stability; traction on uneven road surfaces, while accelerating and through corners; and body attitude under braking.
Vortex Generators
To help streamline the MR, eight small (25 mm height) fins - called vortex generators - were added to the rearward edge of the roof to increase the flow of air down the rear window. This places additional downforce on the window and reduces the resistance of air passing over the roof.
Each of these delta-shaped fins is set to create yaw of approximately 15 degrees on the air current that passes over it. The flow generates a yaw of 15 degrees at the center of the car, and 0 degrees at the outer edges.
The amount of air separation at the rear window (shown in the diagram below) decreases when the vortex generator is present. When the area of separation decreases, the main air current over the roof flows more widely over the window, increasing down force and causing a streamline effect by decreasing the air resistance of the car. Lift and air resistance are lowered in equal proportion.
Warranty and Manufacturing
All Mitsubishi cars and sport utility vehicles are backed by a comprehensive limited warranty that covers the vehicle from bumper-to-bumper for five-years/60,000 miles. In addition, the powertrain is covered by a 10-year/100,000-mile limited warranty, while body panels have a seven-year/100,000-mile anti-corrosion/perforation limited warranty. The program also includes 24-hour emergency roadside assistance with free towing to the nearest authorized Mitsubishi retailer for warranty-related repairs for five years/unlimited miles.
Mitsubishi Motors North America, Inc., (MMNA) is responsible for all manufacturing, finance, sales, marketing, research and development operations of Mitsubishi Motors Corporation in the United States. Mitsubishi Motors sells coupes, convertibles, sedans and sport utility vehicles through a network of approximately 570 dealers.
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