The assessment of using SI engines for medium-duty applications

Abstract

The price of diesel is projected to go up due to increasing demand. The price differential of diesel and gasoline is accordingly projected to increase. As a consequence of the diesel fuel price premium, a diesel engine must be significantly more efficient in terms of gallon/mile or liter/km, just to make up for the higher fuel cost in the US market. In the truck market, the sales of diesel engine share has been going down continuously for class 4 trucks. The decrease may be driven by high diesel fuel prices. This study is to investigate the applicability and economics of replacing a diesel engine with an SI engine in medium duty class 5 applications, where such a switch may have already began. The Ford F550 is offered with both diesel engine and gasoline engine option. From the Ford website, the price difference between the V-10 gasoline engine and the V-8 turbo diesel engine is more than $15,000, although with different performance (gasoline engine with more power, while diesel engine with more torque). The combination of high diesel fuel price relative to gasoline, and high diesel engine and aftertreatment prices opens an opportunity for a cost-effective, fuel-efficient gasoline medium truck engine. There are two main tools that were used in this study - ADVISOR and GEM (Greenhouse Gas Emissions Model). ADVISOR is a set of model, data, and script text files for use with MATLAB and Simulink. GEM is a vehicle simulation tool developed by EPA for compliance with the proposed greenhouse gas emissions standards and fuel efficiency standards for medium and heavy-duty engines and vehicles. The results from the engine simulations provide insight into the comparison of the usability and economy of using an SI engine and a diesel engine in medium duty trucks.After acquiring fuel consumption through various simulation, analysis of total cost of ownership was conducted for different cases..