Like the new-generation Mitsubishi Eclipse coupe, the 2007 Eclipse Spyder is available in two performance levels: The Eclipse Spyder GS is powered by a MIVEC-enhanced 2.4-liter four-cylinder engine mated to either a standard five-speed manual or optional four-speed automatic transmission with Sportronic¨ that allows the driver to select the shift points. The four-cylinder engine delivers 162 hp at 6,000 rpm and 162 lb.-ft. of peak torque at 4,000 rpm with the aid of its patented Mitsubishi Innovative Variable timing Electronic Control (MIVEC) system.
The Eclipse GT is powered by a 3.8-liter SOHC MIVEC V-6 engine mated to a choice of either a standard six-speed manual or optional five-speed Sportronicú transmission. The V-6 develops 260 hp at 5,750 rpm and 258 lb.-ft. of peak torque at 4,500 rpm. (Note: The Eclipse GT coupe is rated at a slightly higher 263 hp and 260 lb.-ft. due to differences in the two models' exhaust systems.)
In addition to utilizing Mitsubishi's Torque Roll Axis Mount system to help control engine movement, the 2007 Eclipse Spyder uses vibration-dampening fluid-filled mounts are utilized for all key engine and transmission mounting points.
Mitsubishi Innovative Valve Timing Electronic Control system (MVEC)
Many carmakers today equip their engines with some type of variable valve control system, which can optimize power and torque by changing valve opening times and/or duration. Another type of system controls valve lift or stroke, which affects airflow into to the combustion chamber. Some of these valve control systems optimize performance at low and mid-range engine speeds. Others focus on enhancing only high-rpm power.
The Mitsubishi Innovative Valve Timing Electronic Control (MIVEC) system provides both of these benefits by controlling valve timing and lift. The Eclipse GS four-cylinder and GT V-6 engines both employ the MIVEC system.
In essence, MIVEC serves the same function as 'swapping cams,' something that car owners and racers might do when modifying older-design engines to produce more power. With MIVEC, the 'swap' occurs automatically at certain engine rpm at wide-open throttle (4,300 rpm in the four-cylinder engine and 4,000 rpm in the V-6). The cam switch operation is transparent to the driver, who is simply rewarded with a smooth flow of power.
Despite its technological complexity, the basic operation of the MIVEC system can be expressed quite simply: MIVEC alters the cam profiles, tailoring engine performance in response to driver input.
Under low-rev conditions, MIVEC selects a smaller cam profile, yielding medium lift on the valves to provide stable combustion and lower emissions. When the throttle is opened wide and engine speed reaches the switchover point, MIVEC gives the intake valves a longer duration and higher lift, providing maximum and efficient power and torque over a broader range of engine speeds.
How MIVEC Works
In the MIVEC system, three distinct cam profiles are used to provide 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 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, which are retained by springs in a lowered position while the engine speed is below the MIVEC switchover point, to avoid contacting the high-lift T-shaped levers.
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.
In summary, MIVEC switches to the higher cam profile as engine speed increases, and drops back to the lower cam profile as engine speed decreases; the low-and high-speed modes overlap for a brief period, boosting torque.
Eclipse Spyder GT: 3.8-Liter MIVEC V-6 Engine
The 2007 Mitsubishi Eclipse Spyder GT is powered by the transversely mounted 3.8-liter, 60-degree, SOHC, 24-valve V-6 engine introduced for the Eclipse coupe in 2006. This new engine was the first V-6 from Mitsubishi to be equipped with the MIVEC valve timing and lift system. Improved liquid-filled engine mounts help reduce vibration and harshness.
An oversquare 95.0 mm bore and 90.0 mm stroke yield the 3,828 cc displacement. In the interest of durability, the 3.8-liter V-6 uses high-pressure cast pistons, forged steel connecting rods and a heat-treated forged steel crankshaft. The durable high nickel content cast-iron 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.
The aluminum cylinder heads employ single-overhead-cam, four-valve-per-cylinder valvetrains. The intake and exhaust port volumes and valve diameters have been designed to maintain optimal mixture velocity at low- to mid-range rpm to help deliver the best off-the-line and passing response. The new engine's key friction surfaces -- such as journals and ring surfaces -- have been treated for lubrication or coated to reduce friction and help optimize fuel efficiency. The 3.8-liter engine's oil pan features 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 engine, the V-6 engine produces a peak of 260 hp at 5,750 rpm and 258 lb.-ft. of peak torque at 4,500 rpm. Just as impressive, the V-6 is producing 220 lb.-ft. of torque before it even reaches 2,000 rpm, giving the Eclipse Spyder GT outstanding off-the-line response.
Induction
Fuel and air delivery to the combustion chambers of the Eclipse Spyder's 3.8-liter V-6 is governed by a throttle-by-wire control system that eliminates the mechanical linkage 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 Spyder GT - the throttle control computer receives data from wheel speed sensors to govern engine speed to help regain traction when necessary.
The V-6 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 electronically controlled throttle body assembly features a double-sided cut throttle shaft for improved airflow.
Cold Air Intake System
All Eclipse models are equipped with a cold-air induction system that feeds ambient air to the intake manifold. The shape of the air inlet duct is designed to draw large volumes of cool, dense, onrushing air from the grille opening while guarding against the intake of water or snow. A sound-absorbing resonator attached to this intake helps reduce intake suction noise. 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 on the 3.8-liter V-6 engine is designed with a smaller secondary air intake port to capture additional cold ambient air while controlling intake noise.
Fuel Delivery
A sophisticated electronically controlled multi-point fuel injection system ensures precision fuel delivery. Six injectors mounted in a lower injection manifold are fed pressurized fuel by a plate-style delivery rail. The plate-style fuel rail design absorbs fuel pulsation and helps generate consistent fuel spray patterns for better atomization. Compared to previous fuel injectors, the new injectors are designed with additional tiny nozzle holes that help decrease mean droplet size, improving fuel atomization by fifty percent.
The electric fuel pump module integrates the fuel filter and high-volume/high-pressure pump into one assembly, reducing the number or parts and connections and enhancing reliability. Carbon, rather than copper, is used for the commutator's brushes to improve the fuel pump's durability. A return-less fuel system minimizes heat transfer to the fuel, which in turn reduces vapor emissions.
Exhaust System
The Eclipse 2.4-liter four-cylinder engine uses a high-flow, welded tubular exhaust manifold. Dual catalytic converters are integrated into the tubular steel assembly near the cylinder heads to more quickly reach operating temperature, thereby promoting quicker, more efficient catalyzation. The stainless steel exhaust system uses a minimum number of hanging points to help reduce vibration transmitted to the body. A high-flow muffler minimizes backpressure while also producing a deep, sporty exhaust note.
The Spyder GT V-6 engine features 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.
Four Different Transmissions
The 2007 Mitsubishi Eclipse Spyder uses four different transmissions across the GS and GT trim levels. The Eclipse GS comes equipped with a standard five-speed manual transmission and offers an optional four-speed automatic transmission.
The Eclipse Spyder GT offers the performance of a standard six-speed manual transmission or an optional five-speed automatic. The six-speed transmission features triple synchronizers on the first three forward gears for smoother engagement. The six-speed shifter utilizes a dual cable linkage for easy, smooth and quick shifting performance. A dual-mass flywheel assembly helps suppress driveline vibration, which along with a self-adjusting clutch, helps to extend clutch life. In addition, a hydraulically operated clutch contributes to smooth, easy and rewarding shifting feel.
Eclipse Automatic Transmissions
The automatic transmissions used in Eclipse models are equipped with a Sportronic¨ mode that offers dynamic manual shifting. Simply moving the shift lever into the sports mode gate gives the driver more fun-to-drive control of manual gear selection.
In both the four-speed automatic (Eclipse GS) and five-speed automatic (Eclipse GT), the latest version of the INVECS II processor helps the transmission match its shifting actions to road conditions and driver input. The INVECS II processor executes optimal shift points. A 'learned control' function in the computer measures the timing of the driver's accelerator inputs and tailors shift action accordingly for softer or firmer shifts.
by Mitsubishi
by Mitsubishi