Innovative Use of Basic Technologies for a High-Efficiency, Low-Cost Small Displacement Gasoline Engine

In recent years, world-wide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent Corporate Average Fuel Economy (CAFÉ), Worldwide harmonized Light vehicles Test Cycles (WLTC) and Real Driving Emission (RDE) targets, as set by international and country’s local regulatory authorities. Many technologies have already been developed or are currently under study by automotive manufacturers for gasoline engines, to meet legislated targets. In-line with the above objective, Maruti Suzuki Engine Design and Development team worked to enhance the efficiency of a small gasoline engine (i.e 0.8 L) applicable for small entry level 5-door hatchback vehicles. Improvements were made in the engine’s thermal and mechanical efficiencies with minimum cost increment considering stringent entry level vehicle cost target. These improvements help to attain the minimum BSFC along with increasing the minimum BSFC area in engine map to decrease the fuel consumption in current Modified Indian Drive Cycle (MIDC) and upcoming World-wide harmonized Light vehicles Test Cycles (WLTC). In this paper, explanation of design methodology and their benefits in the actual engine in terms of fuel economy have been explained for below components:  Thermal Efficiency • Combustion system 1.Fast Combustion (High Tumble Intake port, Piston bowl, and Pent-roof/Combustion chamber, High energy Ignition coil) 2.Cooling Loss Reduction (S/V and Water Jacket optimization) 3.Knock Mitigation (Inter Bore Cooling, Injector spray target improvement, and low SMD for fuel cooling effect using open valve injection) 4.Pumping Loss Reduction (Cooled-EGR and Atkinson Intake cam adoption)  Mechanical Efficiency 1. Valve train architecture upgrade: from Sliding-type to Roller-type. 2. Block Honing: To reduce friction. 3. Low viscosity Engine OIL adoption: Benefit in friction reduction 4. W/P drive ratio optimization: To reduce auxiliary load. Target was to keep the same performance level of engine and vehicle. The overall vehicle level fuel economy target was set to fulfill the CAFÉ-2 requirements. Engine level BSFC improvement was taken based on weighted 6 major fuel consumption points based on MIDC. Additionally, it was mandated to expand the lambda 1 operation range to comply with upcoming RDE legislation. For the same Integrated Exhaust Manifold (IEM) type Cylinder Head (CH) was designed for this project which enabled lambda 1 till rated RPM. Further IEM supports faster Water Jacket (WJ) warm up which benefits in Fuel Economy (FE) improvement in test cycle. After design optimization as per above table with minimum changes to the manufacturing facilities, 8.11% FE improvement has been achieved by upgraded base engine without adding any variable and high-cost technology items like VVT, Variable Oil Pump, electric water pump etc.