MIVEC
From Wikipedia, the free encyclopedia
MIVEC™ (Mitsubishi Innovative Valve timing Electronic Control system)[1] is the brand name of a variable valve timing engine technology developed by Mitsubishi Motors. MIVEC, as with other similar systems, varies the lift of the valves by using two different camshaft profiles. At low speeds, a mild (low-lift) cam lobe provides "normal" performance, while above a fixed engine speed a second set of cam lobes are activated, providing higher lift and duration; therefore a greater quantity of air into the combustion chamber which increases the power output.
MIVEC was first introduced in 1992 in their 4G92 powerplant, a 1,597 cc naturally aspirated DOHC 16 valve straight-4.[2] The first cars to use this were the Mitsubishi Mirage hatchback and the Mitsubishi Lancer sedan. While the conventional 4G92 engine provided 145 PS at 7000 rpm,[3] the MIVEC-equipped engine could achieve 175 PS at 7500 rpm.[4] Similar improvements were seen when the technology was applied to the 1994 Mitsubishi FTO, whose top-spec GPX variant had a 6A12 1997 cc DOHC 24 valve V6 with peak power of 200 PS at 7500 rpm.[5] The GR model, whose otherwise identical powerplant was not MIVEC-equipped, produced 170 PS at 7000 rpm by comparison.[6]
Although initially design to enhance performance, the system has subsequently been developed to improve economy and emissions, and has been introduced across Mitsubishi's range of vehicles, from the i kei car to the high-performance Lancer Evolution sedan. Many implementations only vary the valve timing (the amount of time per engine revolution that the intake port is open) and not the lift.
[edit] MIVEC-MD
In the early years of developing its MIVEC technology, Mitsubishi also introduced a variant dubbed MIVEC-MD (Modulated Displacement),[7][8] a form of variable displacement. Under a light throttle load, the intake and exhaust valves in two of the cylinders would remain closed, and the reduced pumping losses gave a claimed 10–20 percent improvement in fuel economy. Modulated Displacement was dropped around 1996.[7]
[edit] Current implementations
Engine code | Capacity | Configuration | Year |
---|---|---|---|
3A91 | 1124 cc | Straight-3 | (2003–present) |
3B20 | 659 cc | Straight-3 | (2005–present) |
4A90 | 1332 cc | Straight-4 | (2003–present) |
4A91 | 1499 cc | Straight-4 | (2003–present) |
4B11 | 1998 cc | Straight-4 | (2007–present) |
4B12 | 2359 cc | Straight-4 | (2005–present) |
4G15 | 1468 cc | Straight-4 | (2003–present) |
4G19 | 1343 cc | Straight-4 | (2002–present) |
4G63T | 1997 cc | Straight-4 | (2005–present) |
4G69 | 2378 cc | Straight-4 | (2003–present) |
6B31 | 2998 cc | V6 | (2006–present) |
6G75 | 3828 cc | V6 | (2005–present) |
[edit] Footnotes
- ^ "Latest MMC technologies and near-future goals", Mitsubishi Motors website
- ^ History of Mitsubishi, 1990-1999, Mitsubishi Motors website
- ^ 1992 Mitsubishi Lancer RS specifications, English.auto.vl.ru
- ^ 1992 Mitsubishi Lancer Cyborg specifications, English.auto.vl.ru
- ^ 1994 Mitsubishi FTO GPX specifications, English.auto.vl.ru
- ^ 1994 Mitsubishi FTO GR specifications, English.auto.vl.ru
- ^ a b "Mountain of MIVECs", Michael Knowling, AutoSpeed, Issue 346, September 3, 2005
- ^ "Mitsubishi Motors History - Engine Technology", Mitsubishi Motors South Africa website
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