Investigation of Cylinder Deactivation strategies for better fuel consumption using 1-D Simulation Method Izwan Hamid, Mohd Farid Muhamad Said*, Mohd Fadziel Mohamad Nor, Zulkarnain Abdul Latiff Automotive Development Centre (ADC) Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310, Skudai, Johor, Malaysia E-mail : mdfarid@utm.my ABSTRACT In order to meet consumer and legislation requirements, big investments on key technology strategies have been made to ensure fuel consumption is reduced. Recent technologies for gasoline engines are lean combustion technologies (including direct injection and homogenous charged compression ignition), optimizing intake and exhaust valve timing with valve lift and also cylinder deactivation system (CDA) have been practised to improve the engine efficiency. In this study, the purpose is to investigate the engine behaviour when running at different cylinder deactivation (CDA) strategies. One-dimensional engine model software called GT-Power is used to predict the engine performances. There are total of five strategies that have been studied which include normal mode, spark plug off mode, cylinder deactivation mode, intake normal with exhaust off mode, and intake off with exhaust normal mode. Engine performance outputs of each strategy are predicted and compared at BMEP of 3 bars with engine speed of 2500 rpm. Also, the effect of CDA strategies on in-cylinder pressure and pumping loss are performed. The study shows that all of these cylinder deactivation strategies are significantly reduce the pumping loss (PMEP) and fuel consumption, furthermore increasing the thermal efficiency of the engine. The results suggest that the most beneficial strategy for activating CDA is for the case whereby both the intake and exhaust valves are kept closed. This strategy successfully reduced the BSFC. It found that most of these cylinder deactivation strategies improve the engine performance during part load engine condition. Keywords: Cylinder Deactivation, GT-Power, Intake, Fuel Consumption, Pumping Loss 1. INTRODUCTION Deactivating cylinders is one of the proven method to reduce fuel consumption in a multi cylinder engine. The fuel improvement that benefit from deactivating cylinders ranging from 10% to 20% depending on the technological approaches [1-3]. Deactivation means that the cylinder is not producing combustion. There are several ways to deactivate the cylinder. The simplest method is just switching off the ignition. Since the fuel consumption is the main concern, the fuel injector must also be shut off. Other method includes shutting down the intake and exhaust valve from operating. In 1882, Mitsubishi Company tried several techniques of cylinder deactivation on its 1.4L, 4 cylinders Orion MD engine. The techniques are deactivate both intake and exhaust valves, or shut off the fuel supply while supplying fresh air without throttling, or shut off the fuel supply while re-circulating the exhaust gas, or just simply shut off the fuel supply. By doing so, it manage to reduce the fuel consumption up to 42% at certain engine condition [4]. This paper will look into several options of deactivating the cylinders. The methods of deactivating the cylinders will be implemented in a simulation engine model by using GT Power software. Different options of cylinder deactivation should affect the engine performance in different ways. Cylinder deactivation mainly focuses on reducing the pumping loss. Pumping loss is high at part load engine operation due to partially opened throttle valve [5]. This create negative pressure inside the intake manifold. The pumping loss should also be reduced by increasing the intake manifold pressure or by un-throttled operation [6]. Shutting down some cylinders operation will let the working cylinders to do extra work as to produce the same amount of work as if all the cylinders are running. In order to produce more work, the working cylinders need more air. The throttle opening should be opened wider to allow air access to the cylinders. When the throttle opening is open wider, it will increase the pressure in the intake manifold. This will reduce the