Lancer Evolution: Technological marvel

ENGINE

The proven 2.0-liter inline four-cylinder 16-valve DOHC intercooler-turbocharged 4G63 engine - shared across all three iterations of the Lancer Evolution - is now more powerful than ever.

For higher output at mid to high engine speeds, the turbocharger uses the largest possible turbine nozzle. The result is more torque in the 2000-5000 rpm range, as well as output characteristics that keep pulling from the peak output speed of 6,500 rpm all the way to the rev limit.

The turbocharger wastegate valve is now more circular in shape and lighter weight. Turbo boost is 20.3 psi at 3500 rpm and 17.4 psi at 6500 rpm. The 2.0-liter power plant generates class-topping torque of 286 lb-ft at 3500 rpm, and 276 horsepower at 6500 rpm.

MR EDITION EXCLUSIVE EQUIPMENT: SIX-SPEED MANUAL TRANSMISSION

The Lancer Evolution MR Edition is the first Mitsubishi since the 3000GT to be equipped with a six-speed manual transmission. Designed to handle high-torque capacity while providing quick, smooth shifts, the W6MAA unit 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 added to the shift lever provides 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 six-speed transmission and helps to reduce vibration noise.

The six-speed manual transmission is standard equipment on the Evolution MR Edition and is not available on other Lancer Evolutions.

BODY

The Lancer Evolution MR Edition and RS are 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 increase cabin strength, diagonal braces reinforce the roof joints at the front, center and rear pillars.
Aluminum Roof

ACTIVE CENTER DIFFERENTIAL

First employed on the Japanese-market Evolution VII, Mitsubishi's Active Center Differential (ACD) makes its North American debut in Lancer Evolution MR Edition, and also is made standard on all Lancer Evolutions in 2005. Combined with a front helical limited slip differential, the ACD helps raise 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 Edition. 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 MPa to 1 MPa (0 to 145 psi).

FRONT HELICAL LIMITED-SLIP DIFFERENTIAL

With the adoption of the ACD, the front differential is changed from an open differential to a helical limited-slip differential, the same unit found in the Lancer Evolution RS. The helical-type limited slip differential provides better durability and higher performance when it's needed most-while turning. 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.

SPORTS ABS

A Sports antilock braking system (ABS) is standard on Lancer Evolution and MR Editions. 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 under 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, integral with 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.

IMPROVED HANDLING STABILITY, RIDE COMFORT

The Lancer Evolution MR Edition 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 Edition.

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.
Less load transfer means improved grip.

VORTEX GENERATORS

To help streamline the MR Edition, eight small (25 mm in 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 more down force 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 blue 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

As part of Mitsubishi Motors "Best-Backed Car" program, all models are backed by a comprehensive new vehicle 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 "Best-Backed Car" 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 and Canada. Mitsubishi Motors sells coupes, convertibles, sedans and sport utility vehicles through a network of approximately 650 dealers. For more information, contact the Mitsubishi Motors News Bureau at (888) 560-6672 or visit media.mitsubishicars.com.