Mitsubishi 4B1 engine

The Mitsubishi 4B1 engine is a range of all-alloy straight-4 engines built at Mitsubishi's Japanese "World Engine" powertrain plant in Shiga on the basis of the Global Engine Manufacturing Alliance (GEMA).^[1][2][3] Although the basic designs of the various engines are the same, their exact specifications are individually tailored for each partner (Chrysler, Mitsubishi, and Hyundai). The cylinder block and other basic structural parts of the engine were jointly developed by the GEMA companies, but the intake and exhaust manifolds, the cylinder head’s intake and exhaust ports, and other elements related to engine tuning were independently developed by Mitsubishi.^[1]

All engines developed within this family have aluminium cylinder block and head, four valves per cylinder, double overhead camshaft layouts, and MIVEC continuous variable valve timing. The 4B1 engine family is the first to have the continuously variable valve timing MIVEC system applied not only to its intake valves but also to its exhaust valves. The intake and exhaust cam timing is continuously independently controlled and provide four optimized engine operating modes.^[1][4]

4B10

Specifications

Applications

• 2007 Mitsubishi Lancer
• 2010 Mitsubishi RVR
• 2010 Proton Inspira 1.8E

Characteristics

4B11

Specifications

Applications

• 2007 Mitsubishi Lancer
• 2009 Mitsubishi Outlander (Facelift Europe)
• 2010 Mitsubishi ASX
• 2010 Proton Inspira 2.0P

Characteristics

The engines's bore and stroke both measure 86.0 mm, which engineers refer to as square. According to Mitsubishi, the new cylinder dimensions contribute to a free-revving character (max power at 6,500 rpm, redline at 8,000 rpm), linear power delivery and wide torque curve. Mitsubishi used a timing chain instead of a belt for better reliability and iridium spark plugs to lower emissions and to help extend major service intervals for lower cost of ownership. To reduce weight, Mitsubishi used a plastic cam cover and intake manifold and double-layer stainless steel exhaust manifold. The exhaust manifold has a rear location on the transverse engine, compared to the front location for the previous engine, yielding important benefits such as better emissions performance. To lower vibration, Mitsubishi used a 4-point inertial axis system with cylindrical hydraulic engine mounts on the left and right sides. A lightweight, high-rigidity squeeze-cast aluminium bracket on the right side mount (engine side) lowers engine noise under acceleration. A lightweight, high-rigidity steel plate bracket on the left side mount (transmission side) lowers gear noise. A custom-tuned insulator was developed for the front and rear mounts to help control both idle vibration and acceleration shock.^[4]

4B11T

Specifications

Applications

• 2007 Mitsubishi Lancer Evolution
• 2008 Mitsubishi Lancer Ralliart (detuned)

Characteristics

Peak power and torque figures of 206 kW and 422 N·m are for Japanese market Lancer Evolution models^[5] and figures of 217 kW and 407 N·m are for US market models.^[6]

The 4B11T is the first engine in the Lancer Evolution series that uses a die-cast aluminium cylinder block versus the cast-iron block used in the previous turbocharged 4G63 engine that powered all previous models. The engine weight has been reduced by 12 kg (26 lb) compared to the 4G63, even with the addition of a timing chain instead of a belt and MIVEC continuous variable valve timing on both the intake and exhaust camshafts (the 4G63 had MIVEC valve timing & lift switching type on the intake only). A revised turbocharger offers up to 20-percent quicker response at lower engine speeds compared to previous 4G63. The 4B11T offers a broader torque curve, producing more torque than the 4G63 at all engine speeds, helped by the engine's square bore and stroke design (both measure 86.0 mm). Redline starts at 7,000 rpm, with a fuel cutout at 7,600 rpm to protect the engine.^[6]

A semi-closed deck structure, an integrated ladder frame and four-bolt main bearing caps contribute to engine strength, durability and lower NVH levels. Unlike the 4G63, the 4B11T does not use a balancer shaft. The semi-floating pistons of the 4G63 have been replaced with a fully floating pistons for the 4B11T. Aluminium is also used for the timing chain case and cylinder head cover. The engine features an electronically controlled throttle, an isometric short port aluminium intake manifold and the stainless steel exhaust manifold is positioned at the rear of the engine. The use of a direct-acting valvetrain eliminates the need of the roller rocker arm configuration previously used in the 4G63. The 4B11T features built-up hollow camshafts and its valve stem seals are integrated with the spring seats. The internal components of the 4B11T engine have been reinforced to withstand high levels of boost.^[6]

4B12

Specifications

Applications

• 2007 Mitsubishi Delica
• 2008 Mitsubishi Lancer
• 2008 Citroën C-Crosser
• 2008 Peugeot 4007
• 2009 Mitsubishi Lancer Sportback GTS

Characteristics

The cylinder head intake and exhaust ports and intake and exhaust manifolds are shape optimized for better volumetric efficiency. Mitsubishi lowered the friction of the engine by including elastic grinding of the valve stems, adopting a high-efficiency shroud equipped plastic impeller in the water pump and using 0W-20 low-viscosity oil. Mitsubishi increased the combustion efficiency by optimizing the design of the cylinder head intake and exhaust ports, by incorporating the MIVEC system on both intake and exhaust valves and by using injectors that give an ultra micro droplet fuel spray. To lower the engine's weight, Mitsubishi used die-cast aluminium for the cylinder block, plastic for the cylinder head cover and intake manifold, and stainless steel for the exhaust manifold. The engine features a compact balancer shaft module with an integrated oil pump. A silent chain is used to drive the camshafts. The compact balancer module, the silent chain, the stable combustion yielded by the intake and exhaust MIVEC system, and high rigidity designs for the cylinder head and cylinder block realize low vibration and noise.^[1]

See also

• List of Mitsubishi engines

References