MIVEC 2.4 4G69 INFO **Ralliart**
#1
07-25-2006, 11:48 PM
MIVEC 2.4 4G69 INFO **Ralliart**
New For 2004: Mitsubishi's 4G69 MIVEC Engine
October 31, 2003 -- Cypress, CA. -- The 2.4-liter SOHC four-cylinder engine found in the 2004 Mitsubishi Lancer Ralliart, Lancer Sportback and Outlander 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.
VARIABLE LIFT TECHNOLOGY
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 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.
BETTER PERFORMANCE AT THE FLIP OF A SWITCH
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.
SUMMARY
Under low-rev conditions the low- and mid-lift cam lobes drive the intake valves, providing slightly 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.
ENGINE MODIFICATIONS
Besides being enhanced with MIVEC, 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 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. The weight of each connecting rod was reduced from 623 g to 530 g. 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.
Write up thans to DirtWagon
October 31, 2003 -- Cypress, CA. -- The 2.4-liter SOHC four-cylinder engine found in the 2004 Mitsubishi Lancer Ralliart, Lancer Sportback and Outlander 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.
VARIABLE LIFT TECHNOLOGY
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 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.
BETTER PERFORMANCE AT THE FLIP OF A SWITCH
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.
SUMMARY
Under low-rev conditions the low- and mid-lift cam lobes drive the intake valves, providing slightly 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.
ENGINE MODIFICATIONS
Besides being enhanced with MIVEC, 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 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. The weight of each connecting rod was reduced from 623 g to 530 g. 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.
Write up thans to DirtWagon
#2
06-14-2011, 06:43 AM
Hi,
Just like to say it's a nice post. You've done a good job posting such informative post. Keep up the good work.
Just like to say it's a nice post. You've done a good job posting such informative post. Keep up the good work.
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jazziat
Mitsubishi Lancer and Lancer Sportback
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11-08-2009 03:00 AM
2006, 24, 4g69, compression, diameter, engine, exhaust, liter, maintenance, mitsubishi, mivec, parts, performance, piston, ralliart, superchargers
