2004 Mitsubishi Galant - Powertrain

The 2004 Mitsubishi Galant is available with a choice of two powerful new engines. The DE and ES trim lines come equipped with a 2.4-liter four-cylinder unit that's mated to a four-speed automatic transmission. This engine delivers 160 horsepower and 157 pound-feet of torque with the aid of its patented Mitsubishi Innovative Variable timing and lift Electronic Control (MIVEC) system. For even more performance, the LS and GTS trim lines include a high-displacement, high-output 3.8-liter SOHC V6 engine mated to a four-speed Sportronic(TM) transmission that allows the driver to select shift points. The new V6 develops 230 horsepower and 250 pound-feet of torque, the highest torque rating in the class.

4G69: 2.4-Liter SOHC Four Cylinder Engine

The 2.4-liter SOHC four-cylinder engine found in the Galant DE and ES trim lines 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, which provides stable combustion and lower emissions. But when the throttle is opened wide and engine speed increased, MIVEC allows the 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 (160 horsepower and 157 pound-feet of torque) 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 that are retained by springs in a lowered position at less than 3500 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 help 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 3500 rpm, 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 at 3600 rpm as engine speed increases, and drops back to the lower cam profile at 3400 rpm as engine speed decreases; the output torque of the low- and high-speed modes overlap at those speeds. This also means that the cam switch operation is virtually 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.

2.4-Liter Engine Modifications

But beside the MIVEC system enhancement, the 2.4-liter (4G69) engine has received a number of other mechanical updates that help it breathe and exhale more efficiently, as well as several improvements to help reduce the weight of moving parts. All of the following feature comparisons are to the current 2.4-liter (4G64) engine:

• Intake. Several modifications were made to improve both efficiency and performance. Starting with the incoming air, the aluminum intake manifold's interior surface was smoothed to increase intake efficiency. The intake runners are also longer, and they feature a bell-mouth shape to reduce air intake resistance.
• Exhaust. More air coming in means more air needs to get out, so the exhaust manifold was switched from single to dual ports, which reduces interference and improves the flow of gases out of the combustion chamber.
• Rocker cover. For better noise reduction and to reduce weight, the rocker cover is made of aluminum instead of steel.
• Combustion. More efficient combustion has been achieved by increasing the compression ratio to 9.5:1 (from 9.0:1).
• Valves. To improve high-speed efficiency, the valve sizes were increased - intake valves are larger by 1 millimeter in diameter (to 34 mm), and exhaust valves were increased by 1.5 mm in diameter (to 30.55 mm).
• Pistons. With the compression height reduced, the piston height was reduced to match. Even though the pistons have a slightly larger diameter (87 mm versus 86.5 mm), they are significantly lighter in weight (278 grams per unit compared to 354 grams). For moving parts, lower mass also means better efficiency.
• Connecting rods. Each connecting rod was reduced from 623 g to 530 g of weight.
• Crankshaft. Once again engineers found a way to reduce the mass of a moving part. The crankshaft's weight was reduced from 15.8 kg to 14.9 kg. In addition, the crankshaft pulley's weight was reduced at the same time its size was increased. By using aluminum in the hub in place of steel, the pulley's weight was reduced from 2.9 kg to 1.8 kg, a savings of 1.1 kg.
• Timing belt. Weight and friction were reduced by shortening the width of the timing belt. To further reduce weight, the auto tensioner is now made of aluminum instead of cast iron.
• Serpentine drive belt. The 4G69 MIVEC engine uses a single serpentine belt to operate the engine's accessory drives for the power steering, alternator, and air conditioning unit. In addition to saving space compared to the dual-belt drive system used on the previous engine, the low-maintenance serpentine belt features an auto tensioner.

Cylinder Block

The height of the cylinder block was reduced to decrease weight, and the water jacket's length was shortened to help warm the engine faster for better fuel consumption. Also, air bleed holes were added to the main webs to reduce piston moving resistance, which is created by pressure pulsation when the piston is in motion. Also, the new cylinder block reroutes the oil returning from the head to reduce interference between the oil and the rotating crankshaft.

6G75: 3.8-Liter V6 Engine

The 2004 Mitsubishi Galant LS and GTS models are powered by a transversely mounted 3.8-liter, 60-degree V6 engine designed to engage drivers with a broad, responsive torque curve. The engine, designated 6G75, is an evolution of the smooth and powerful 3.5-liter V6 that powers the Mitsubishi Diamante.

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 high nickel content cast-iron, 60-degree engine block is dimensionally taller than the 3.5-liter engine's block and 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 chassis 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.

This free-revving engine package produces a peak of 230 horsepower at 5250 rpm with peak torque of 250 pound-feet occurring at 4000 rpm.

Induction

Fuel and air delivery to the combustion chambers of Galant'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 also been integrated into the vehicle's main ECU. With 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 Galant LS and GTS-the throttle control computer receives data from wheel speed sensors to govern engine speed and regain traction when necessary.

Cold Air Intake System

Galant 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 Galant's 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.

Fuel Delivery System

The 2004 Mitsubishi Galant 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 Galant's injectors are designed with additional tiny nozzle holes that help increase mean droplet size, improving fuel atomization by 50 percent.

The Galant'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 Galant utilizes high-flow, welded tubular exhaust manifolds to expel the engine's spent fumes. The catalytic converter is integrated into the clamshell assembly near the cylinder heads where they can sooner achieve effective operating temperature, retain heat and promote quicker, more efficient catalyzation and increase emissions performance. The rest of the stainless steel exhaust system is designed to utilize a minimum number of hanging points, which lessens the amount of vibration transmitted to the body. A high-flow muffler minimizes backpressure while also producing a pleasant, sporty exhaust note.

Cooling System

The Galant is equipped with a high-capacity aluminum radiator 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 400 mm x 16 mm.

Automatic Transmissions

The Galant is available with two different four-speed automatic transmissions. These transmissions integrate next-generation electronic controls with more refined mechanical technologies to offer superior driving satisfaction, performance, and durability. The Galant's versions of the four-speed automatics build 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 Galant's 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, the four-speed transmission mated to the V6 is 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.

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