| Mitsubishi 3B2 engine | |
|---|---|
 | |
| Overview | |
| Manufacturer | Mitsubishi Motors |
| Production | 2005–2020 |
| Layout | |
| Configuration | Three cylinder |
| Displacement | 0.7–1.0 L (659–999 cc) |
| Cylinder bore | 65.4 mm (2.57 in) 72 mm (2.83 in) |
| Piston stroke | 65.4 mm (2.57 in) 81.8 mm (3.22 in) |
| Cylinder block material | Aluminum die cast |
| Cylinder head material | Aluminum die cast |
| Valvetrain | Direct acting DOHC, 12 valves, intake continuously variable valve timing MIVEC |
| Compression ratio | 8.8:1-10.8:1 |
| Combustion | |
| Turbocharger | On 3B20T only |
| Fuel system | Fuel injection |
| Fuel type | Gasoline |
| Cooling system | Water-cooled |
| Output | |
| Power output | 38–50 kW (52–68 PS) |
| Torque output | 57–95 N⋅m (42–70 lb⋅ft) |
| Dimensions | |
| Length | 286 mm (11.3 in) |
| Height | 191 mm (7.5 in) |
| Dry weight | 67 kg (148 lb) |
| Chronology | |
| Predecessor | Mitsubishi 3G8 engine |
| Successor | NMKV BR06 engine |
The Mitsubishi 3B2 engine is a family of all-alloy three cylinder engines developed by Mitsubishi Motors, first produced in December 2005 at the company's Mizushima powertrain facility in Kurashiki, Okayama,[1] for introduction in their 2006 Mitsubishi i kei car. All engines developed within this family have aluminum cylinder block and head, double overhead camshafts, four valves per cylinder, and MIVEC continuous variable valve timing.[1][2]
The 3B20 was designed with the "rear midship" layout in mind but is not limited to that. The basic dimensions chosen reduced the powerplant's height, the cylinder block's structure was simplified, a timing chain was adopted, modularized components were used for the oil and water pumps, engine mounts, and fuel system.[1] The aluminum construction and lightweight parts and materials in the manifolds helped reduce the weight of the engine by 20 percent compared with its iron-block 3G83 predecessor, while gains were also seen in torque, fuel economy and emissions.[1] Bore pitch is 80 mm.
The preliminary version of the 0.7 L (659 cc) engine was first seen in the "i" Concept test car introduced in 2003, and used Mitsubishi's Smart Idling system which turns off the engine automatically when the vehicle is stationary, and can restart it within 0.2 seconds.[3] So equipped, Mitsubishi claimed the prototype was capable of fulfilling the "three litre initiative" for gasoline engines, meaning fuel consumption of no more than 3 L/100 km (94 mpg‑imp; 78 mpg‑US).[3]
The larger 1.0 L (999 cc) capacity of the development engine was outside the limits of the kei class in Japan and was introduced in the second generation of the smart fortwo.[4]