Intake & Fuel Systems

The Mitsubishi 4B1 engine is the newest 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). more...

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Although the basic designs of the various engines are the same, their exact specifications are individually tailored for each partner. 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.

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.

4B10

Specifications

Applications

2007 Mitsubishi Lancer;

Characteristics

4B11

Specifications

Applications

2007 Mitsubishi Lancer;

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 (6,500 rpm redline, 8000 rpm final), linear power delivery and wide torque curve. Mitsubishi used a timing chain instead of a belt for better reliability, 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.

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