The new 4-cylinder 1.5L turbocharged GDI engine from SAIC
SAIC Motor Corporation Limited (SAIC Motor) has developed a new 1.5 L 4-cylinder turbocharged gasoline direct injection engine to meet the market demand and increasingly stringent requirement of CAFÉ and tail-pipe emission regulations. A series of advanced technologies for improving engine fuel economy、engine-out emission and low-end torque performance have been employed, such as: central gasoline direct injection, integrated exhaust manifold, high tumble combustion system, Miller Cycle, cooled external EGR, 35MPa fuel injection system, multi-hole injector with variable hole size design, efficient turbo charging with EWG, etc. As a result, the engine is able to achieve over 39% brake thermal efficiency (BTE), as well as substantial fuel consumption reduction in vehicle driving cycle. It also delivers 275 Nm torque staring from 1750RPM, with fast low-end torque response. By integrating the 35 MPa high pressure fuel injection system and optimized multi-hole fuel spray, the engine-out particulate numbers (PN) emission is reduced by more than 70% over a previous base engine with 20Mpa fuel injection system. And the vehicle equipped with this new engine is capable of meeting China VI b standard emission regulatory requirement without gasoline particulate filter (GFP).
In this paper, the engine layout and design/optimization of the combustion system will be described. The detailed investigations of effects of the core technologies will also be presented: effect of high tumble port and masking design, effect of fuel spray pattern optimization, Miller cycle vs. Otto cycle, cooled LP-EGR vs. HP-EGR, 35MPa vs. 20MPa fuel injection system, EWG vs. pneumatic waste-gate turbo charger.