Envirofit - Media - Publication Archive :: BAQ 2004 Emissions Characterization of 2-Stroke Engine

EMISSIONS CHARACTERIZATION OF A DIRECT INJECTION RETRO-FIT KIT FOR SMALL TWO-STROKE CYCLE ENGINES

By Tim Bauer, Nathan Lorenz, Dr. Bryan Willson
2004

ABSTRACT
The Asian Development Bank estimates that there are over 100 million motorcycles in Asia (not including India). Current estimates are that at least 50 million of these are powered by two-stroke cycle ("2-stroke") engines, and that these 2-stroke motorcycles have the potential to emit some species of air pollution in quantities roughly equivalent to 2.5 billion modern automobiles. In Asian countries 2-stroke engines are responsible for powering motorbikes, mopeds, "three-wheelers", "autorickshaws", "tuk-tuks", and "tricycles". Emissions from these vehicles’ 2-stroke engines are characterized by high levels of unburned hydrocarbon’s (UHC’s), carbon monoxide (CO), and particulate matter (PM). Direct in-cylinder fuel injection ("direct injection", "DI") is a technology that has shown significant ability to greatly reduce UHC, CO, and PM emissions while simultaneously improving fuel economy. A 2-stroke Kawasaki HDIII 125cc motorcycle was retrofitted with direct injection and an electronic engine management system. The motorcycle was coupled to an eddy current dynamometer and a test protocol was devised to simulate the Indian Drive Cycle. Steady state measurements were taken in the carbureted and DI states to characterize potential improvements. Using the DI system, fuel efficiency was increased by 32%, hydrocarbon emissions were reduced by 88%, and CO emissions were reduced by 72%. PM emissions were not quantified during this study, but all visible exhaust smoke was eliminated. A non-profit corporation has been formed to disseminate the DI retrofit technology and a field test is currently being launched in the Philippines. Plans are presented for the field test, further technical development, and the overall dissemination strategy.

INTRODUCTION
The Asian Development Bank estimates that there are over 100 million motorcycles in Asia (not including India). Current estimates are that at least 50 million of these are powered by two-stroke cycle ("2-stroke") engines, and that these 2-stroke motorcycles have the potential to emit some species of air pollution in quantities roughly equivalent to 2.5 billion modern automobiles. In Asian countries 2-stroke engines are responsible for powering motorbikes, mopeds, "three-wheelers", "autorickshaws", "tuk-tuks", and "tricycles". Emissions from these vehicles’ 2-stroke engines are characterized by high levels of unburned hydrocarbon’s (UHC’s), carbon monoxide (CO), and particulate matter (PM). Direct in-cylinder fuel injection ("direct injection", "DI") is a technology that has shown significant ability to greatly reduce UHC, CO, and PM emissions while simultaneously improving fuel economy. A 2-stroke Kawasaki HDIII 125cc motorcycle was retrofitted with direct injection and an electronic engine management system. The motorcycle was coupled to an eddy current dynamometer and a test protocol was devised to simulate the Indian Drive Cycle. Steady state measurements were taken in the carbureted and DI states to characterize potential improvements. Using the DI system, fuel efficiency was increased by 32%, hydrocarbon emissions were reduced by 88%, and CO emissions were reduced by 72%. PM emissions were not quantified during this study, but all visible exhaust smoke was eliminated. A non-profit corporation has been formed to disseminate the DI retrofit technology and a field test is currently being launched in the Philippines. Plans are presented for the field test, further technical development, and the overall dissemination strategy.

In order to address one of the largest contributors to air pollution in the developing world, EnviroFit International Ltd., was established as a non-profit corporation. The company is focused on improving global health through the development and dissemination of technology solutions to environmental problems in the developing world. EnviroFit is initially focusing on air pollution; specifically on the dissemination of retrofit technology that reduces emissions from 2–stroke cycle ("two-stroke", "2-stroke") engines. Two-stroke engines are used in motorcycles, "three wheelers", "autorickshaws", "tuk tuk’s", and "tricycles" throughout Asia and Africa for basic transportation. While powerful and reliable, they are a major source of air pollution. In the Philippines, 2-stroke engines are used to power over 1.3 million threewheeled "tricycles" which are used as taxis. The pollution from these tricycles contributes heavily to the 2000 premature deaths, 9000 cases of severe respiratory illness, and $430 million in economic costs which occur each year as a result of poor air quality. EnviroFit seeks to improve health by reducing 2- stroke emissions in Asia and Africa, thereby eliminating millions of tons of carbon monoxide, unburned hydrocarbons, particulates, and greenhouse gases.

Over the past three decades, emissions levels in the U.S. and Europe have been reduced dramatically. Until recently, however, less effort has been focused on addressing the soaring levels of emissions in the developing world. The Engines and Energy Conversion Laboratory (EECL) at Colorado State University (CSU) is a leader in developing technology to reduce emissions and fuel consumption from internal combustion engines and has developed a number of products which are now in widespread commercial production. One successful example is electronic direct-injection retrofit technology for the large 2-stroke engines which are used in stationary industrial applications. In 2002, the EECL demonstrated a retrofit direct injection system which dramatically reduced emissions from 2-stroke snowmobiles. The results attracted the attention of several groups who were looking for technology solutions to emissions from 2- stroke engines. After extensive exploration, the EECL decided to apply its expertise to develop an emissions reduction system that can be retrofitted onto existing 2-stroke "tricycle" engines in the Philippines. A Philippine tricycle consists of a simple 2-stroke engine which is bolted to a covered sidecar and operated as a taxi. If the retrofit technology is to have significant impact, it must be disseminated on a large scale. In order to facilitate the rapid development and dissemination of the DI retrofit solution, a nonprofit 501(c)(3) corporation, EnviroFit International, has been formed. EnviroFit’s initial focus is to disseminate high-quality retrofit kits - initially in the Philippines but then potentially to other countries in Asia and Africa with large populations of 2-stroke vehicles. In the Philippines, EnviroFit is working closely with local stakeholders, including NGOs, foundations, aid agencies, environmental gropus, universities, local governments, and representatives of the tricycle drivers’ unions.

Typical 2-stroke engines lose approximately 35% of their fuel in the process of "scavenging" the engine. Scavenging of a 2-stroke engine involves using pressurized air or an air/fuel mixture to flush the exhaust products from the cylinder. During the scavenging process, approximately 35% of the scavenging air or air/fuel mixture "short-circuit" through the engine and are lost. In the simple "crankcase-scavenged" engines used in most small vehicles, air and fuel are mixed in a carburetor before entering the engine, and scavenging is performed with this air/fuel mixture, resulting in the loss of approximately 35% of the fuel. These scavenging fuel losses are responsible for the high emissions and high fuel consumption of simple crankcase-scavenged 2-stroke engines. The retrofit system being developed by EnviroFit, the "EnviroKit™", utilizes "direct injection" (DI) of fuel into the cylinder to eliminate scavenging fuel losses. The EnviroKit™ combines patented direct injection technology from the Orbital Engine Corporation (Perth, Australia) with the EECL’s prior experience in developing retrofit solutions for large 2-stroke engines. An initial "alpha unit" DI tricycle prototype was developed in 2003 and demonstrated in Manila in November and December of 2003. The enthusiastic response from drivers, government officials, and the environmental community prompted the development of a plan for a large-scale dissemination effort, preceded by a field test validation program.

A retrofit program only makes sense if there are significant reductions in emissions. And, for the retrofit program to be self-sustaining, the technology should provide an economic benefit that will entice drivers to invest in the solution. Thus, the retrofit kit must provide a significant reduction in emissions and fuel consumption. The primary goal of the initial research and development done at the EECL was to validate the performance improvements of the EnviroKit™ retrofit kit

It should be emphasized that the EECL and / or EnviroFit did not invent the DI technology. The EECL has played a large role in developing DI technology for large industrial engines, and is now working to adapt DI technology as a retrofit technology for small engines. One of the leaders in developing DI technology for small engines is the Orbital Engine Corporation in Perth, Australia. Their technology is manufactured by Synerject, a joint venture of Orbital and Siemens located in the United States. The EnviroKit™ uses an Orbital fuel injector manufactured by Synerject. Orbital / Synerject DI systems are in widespread use in many OEM (original equipment manufacturer) applications such as outboard motors and personal watercraft. In order to achieve the goals of the retrofit program, EnviroFit needed to demonstrate that the EnviroKit™ produces comparable emissions reductions to previous retrofit and OEM efforts undertaken by both the Orbital Engine Corporation and the EECL3,4. The engine test program described in this paper was undertaken to document the emissions and fuel savings from the EnviroKit™.