The 2006 Mitsubishi Eclipse is available with a choice of two powerful new engines. The Eclipse GS is equipped with a MIVEC-enhanced 2.4-liter four-cylinder engine mated to either a five-speed manual or four-speed automatic transmission with Sportronic(TM) that allows the driver to select the shift points. The four-cylinder engine (designated 4G69) delivers 162 horsepower (6000 rpm) and 162 lbs.-ft. of torque (4000 rpm) with the aid of its patented Mitsubishi Innovative Variable timing and lift Electronic Control (MIVEC) system.

Breaking new ground in performance, the Eclipse GT is powered by a high-displacement, high-output 3.8-liter SOHC MIVEC V6 engine (6G75) mated to a choice of either a six-speed manual or five-speed Sportronic(TM) transmission. The new V6 in the Eclipse GT develops 263 horsepower and 260 lbs.-ft. of torque, the highest torque rating in its class.

4G69: 2.4-Liter SOHC Four-Cylinder Engine

The 2.4-liter SOHC four-cylinder engine utilizes advanced Mitsubishi Innovative Valve timing and lift Electronic Control (MIVEC) system technology to improve power output over a wide rpm range without sacrificing emissions or fuel economy in the process.

The MIVEC system features separate cam profiles for high and low engine speed modes, which translates to higher maximum power and increased usable torque in the widest variety of driving conditions. Under low-rev conditions, MIVEC selects the smaller cam profile, yielding medium lift on the cam profile which provides stable combustion and lower emissions. But when the throttle is opened wide and engine speed reaches 4300 rpm, MIVEC allows the intake valves a longer duration and longer stroke, thus providing maximum and efficient power and torque over a broader range of engine speeds.

The enhanced power output of the MIVEC system is achieved by its ability to vary the lift and duration of the intake valves. In the MIVEC system, there are three distinct cam profiles that create two engine modes: a low-speed mode, consisting of low- and mid-lift cam profiles; and a high-speed mode. The low- and mid-lift cams and rocker arms - which drive separate intake valves - are positioned on either side of a centrally located high-lift cam. The high-lift cam is directly connected to a T-shaped lever, which controls valve lift and duration of both intake valves in the high engine-speed mode.

At lower engine speeds, the T-shaped levers connected to the high-lift cams reciprocate freely without contacting intake-valve rocker arms, thus allowing the low- and mid-lift cam lobes to control corresponding intake-valve lift and timing. The intake rocker arms contain internal pistons retained by springs in a lowered position at less than 4300 rpm, to avoid contacting the high-lift T-shaped levers. The benefit of the dual-profile low-speed mode is to induce swirl within the cylinder, which helps create stable combustion and improve emissions.

The high-speed mode opens the valves longer due to its higher lift. At high engine speeds, the pistons within the rocker arms elevate when MIVEC sends increased oil pressure through an oil control valve. The high-lift cams' T-shaped levers are then able to directly contact the elevated rocker-arm pistons, overriding the low-speed cam lobes and fully controlling intake-valve lift and duration.

The switch occurs at approximately 4300 / 4000 rpm 4G69 / 6G75), when the powertrain control module opens the valves longer to increase the amount of intake airflow, resulting in higher engine output. More precisely, MIVEC switches to the higher cam profile as engine speed increases, and drops back to the lower cam profile as engine speed decreases; the output torque of the low- and high-speed modes overlap for a brief period. This also means that the cam switch operation is transparent to the driver, who is simply rewarded with more power.

Under low-rev conditions the low- and mid-lift cam lobes drive the intake valves, providing better fuel economy and lower emissions. But when the throttle is opened wide and engine speed increased, MIVEC gives the valves a longer duration and higher lift, thus providing maximum and efficient power and torque over a very broad range of engine speeds. Despite its technological complexity, the basic workings of the MIVEC engine system can be expressed quite simply: MIVEC alters the cam profiles, tailoring engine performance to suit your driving needs.

6G75: 3.8-Liter MIVEC V6 Engine

The 2006 Mitsubishi Eclipse GT is powered by a transversely mounted 3.8-liter, 60-degree, SOHC, 24-valve V6 engine, which is equipped with the MIVEC system for the first time.

The new 3.8-liter displacement is the result of an oversquare 95.0 mm bore combined with a 90.0 mm stroke to achieve its 3828 cc displacement. In the interest of durability, the 3.8-liter engine's pistons are high-pressure castings attached to forged steel connecting rods that swing from a heat-treated forged steel crankshaft. The durable high nickel content cast-iron, 60-degree engine block features revised oil passages for improved lubrication and durability. In addition, the 3.8-liter block is a new casting that has been structurally enhanced for additional cylinder-bore rigidity and includes improved liquid-filled mounting points to reduce vibration and harshness. A pair of single-overhead-cam, four-valve-per-cylinder aluminum heads sit atop this cast-iron block; their intake and exhaust port volumes and valve diameters have been carefully designed to maintain optimal mixture velocity at low- to mid-range rpm to help deliver the best off-the-line and highway passing response. The new engine's key friction surfaces such as journals and ring surfaces have been treated to improved surfaces for lubrication or coated to reduce friction, and help improve gas mileage. The 3.8-liter engine's oil sump includes additional baffling to help control oil flow and ensure oil supply under high cornering loads.

With the help of the same MIVEC technology found on the 2.4-liter four-cylinder, the V6 engine produces a peak of 263 horsepower at 5750 rpm and 260 lbs.-ft. of torque at 4500 rpm.

Induction

Fuel and air delivery to the combustion chambers of the Eclipse's 3.8-liter motor is governed by a throttle-by-wire control system that eliminates the mechanical control between the accelerator pedal and the throttle plate. The throttle-valve-control microprocessor has been integrated into the vehicle's main ECU. In this arrangement, inter-processor communication that would otherwise be transmitted by a complex body of harnesses and connectors is now handled by a circuit board, improving the system's reliability. Acting in conjunction with traction control- a standard feature on the Eclipse GT- the throttle control computer receives data from wheel speed sensors to govern engine speed and regain traction when necessary.

The 6G75 engine achieves its excellent throttle response characteristics thanks in part to a tuned intake manifold and modified throttle body assembly. Port diameters, runner lengths, and plenum volume were optimized for mid-range power and responsiveness. The Eclipse's electronically controlled throttle body assembly features a double-sided cut throttle shaft for improved airflow.

Cold Air Intake system

The Eclipse is fitted with a cold-air induction system that feeds ambient air to the intake manifold, which helps improve engine performance. The shape of the air inlet duct is designed to guard against the ingestion of water or snow, and draws large volumes of cool, dense, onrushing air from the grille opening. A sound-absorbing resonator attached to this intake ducting helps reduce intake suction noise. The Eclipse intake system removes particulate from the incoming air using a low-restriction filter element that is contained in a sturdy air cleaner housing. A resonator is also used on the injection molded thermoplastic intake hose that leads from the air cleaner assembly to the engine. The cold air intake system equipped on the 3.8-liter V6 engine is designed with a smaller secondary air intake port to capture additional cold ambient air while controlling intake noise.

Fuel Delivery System

The 2006 Mitsubishi Eclipse relies on a sophisticated electronically controlled multi-point fuel injection system to ensure precision fuel delivery. The injection system is coupled with a throttle-by-wire control that offers the advantage of computer controlled and instantaneous acceleration response. The fuel delivery is handled by six injectors mounted in a lower injection manifold that are fed pressurized fuel by a plate-style delivery pipe.

A plate-style fuel-rail design absorbs fuel pulsation and helps generate consistent fuel spray patterns for better atomization. Compared to previous fuel injectors, the Eclipse's injectors are designed with additional tiny nozzle holes that help increase mean droplet size, improving fuel atomization by 50 percent.

The Eclipse's electric fuel pump module integrates the fuel filter and high-volume/high-pressure pump into one assembly, reducing the number or parts, connections, and potential for leaks while also improving overall system reliability. To improve the fuel pump's durability, the material used for the commutator's brushes are composed of carbon instead of copper. The in-tank mounted fuel pump moves fuel from the rear of the vehicle to the engine bay using a return-less fuel plumbing system. By eliminating the need for a return line, the amount of heat transferred from the engine to the fuel tank has been minimized to help keep the fuel supply as cool as possible, resulting in a reduction in fuel vapor emissions.

Exhaust

The engines in four-cylinder equipped Eclipse coupes utilize high-flow, welded tubular exhaust manifolds to expel the engine's spent fumes. Dual catalytic converters are integrated into the tubular steel assembly near the cylinder heads to more efficiently achieve operating temperature, retain heat and promote quicker, more efficient catalyzation to help reduce emissions. The rest of the stainless steel exhaust system is designed to utilize a minimum number of hanging points, which reduces the amount of vibration transmitted to the body. A high-flow muffler minimizes backpressure while also producing a pleasant, sporty exhaust note.

The Eclipse's six-cylinder engine removes spent fumes through a pair of efficient, clamshell-type exhaust manifolds. A catalytic converter housed within the clamshell of each manifold helps improve exhaust emissions performance particularly under cold start conditions.

Cooling System

The Eclipse is equipped with an efficient aluminum radiator core with plastic tanks that is very effective at transferring heat from the circulating coolant. This radiator uses dual electrical fans that are mounted in an airflow-efficient shroud for optimal cooling at low vehicle speeds. The radiator core size is 757 mm x 350 mm x 16 - 1.125 mm for all models of Eclipse with 320 mm dual fans and an efficient shroud for both engines.

Transmissions

The 2006 Mitsubishi Eclipse offers four different transmissions across the GS and GT trim levels. The 2.4-liter equipped Eclipse GS is available with either a five-speed manual transmission or a four-speed automatic transmission. The six-cylinder equipped Eclipse GT achieves improved fuel economy and performance with the help of a five-speed automatic and a six-speed manual transmission. The new six-speed transmission features triple synchros for smoother engagement on the first three forward gears. The six-speed shifter utilizes a pull ring to bypass a reverse shift inhibitor, and is actuated by a smooth dual cable linkage for easy, smooth and fast shifting motions. The six-speed equipped Eclipse models utilize a dual-mass flywheel assembly that helps suppress driveline vibration, which along with a self-adjusting clutch, helps to extend clutch life. The clutch assembly is engaged to the flywheel by a concentric, hydraulic slave cylinder that affords superior clutch pedal feel.

Dual Mass Flywheel (DMF)

• Newly developed Dual Mass Flywheel
• Superior noise and vibration suppression

Self Adjustment Clutch (SAC)

• Constant clutch pedal effort over clutch life
• Extended clutch life

Concentric Slave Cylinder (CSC)

• Superior clutch pedal feeling according to high efficiency
• Weight reduction

Automatic Transmissions

The Eclipse is available with two different automatic transmissions, depending on engine. These transmissions integrate next-generation electronic controls with more refined mechanical technologies to offer superior driving satisfaction, performance and durability. The Eclipse's version of the four-speed automatics builds upon years of accumulated development in design and production technologies to produce transmissions with superior structural rigidity, enhanced durability, improved efficiency and reduced weight.
Both of the Eclipse's automatic transmissions are equipped with the latest version of the INVECS II processor that helps the transmission match its shifting actions to both the road conditions and the operator's driving style and inputs. INVECS II provides drivers with what they perceive to be the optimum shift points. It also includes a "learned control" function whereby the computer measures the timing of the driver's accelerator inputs and tailors shift action accordingly for softer or firmer shifts. In addition, both automatic transmissions are equipped with a Sportronic(TM) mode that offers dynamic manual shifting by simply moving the shift lever into the sports mode gate for more fun-to-drive control.

Fluid Filled Engine Mounts

In addition to utilizing Mitsubishi's Torque Roll Axis Mount system to help control engine movement, the 2006 Eclipse uses optimally tuned fluid-filled mounts as an additional measure of engine vibration control to provide increased ride comfort. Vibration dampening, fluid-filled mounts are utilized for all key engine and transmission mounting locations.