SwRI studying low-emissions propane tractor engine
Author: Diesel Progress North American Edition

The Environmental Protection Agency' proposed Tier 3 emission standards for off-road engines promise significant, long-term improvements in air quality. The standards also represent major challenges to engine manufacturers and may encourage the use of alternative fuels such as propane to meet the most stringent aspect of the regulations.

Emissions reduction in off-road vehicles and equipment can be particularly challenging because the equipment uses a broad range of engine sizes for greatly varying applications. Demanding operating environments include excessive heat, dust, and moisture. Additionally, these engines are frequently naturally aspirated. Therefore, solutions to the emissions challenges used in the on-highway vehicle market which are typically turbocharged, are not always practical.

Researchers at the Southwest Research Institute (SwRI), San Antonio, Texas, haw developed a propane-fueled engine for off-highway vehicles that represents a low emissions alternative to traditional diesels. The propane engine, which features a lean-burn combustion system and electronic controls, meets the Tier 3 emission standards scheduled to go into effect in 2008 while rivaling the performance and fuel economy of a diesel engine. The 77 lip Deere engine has replaced an 81 hp diesel engine in a John Deere 5410 tractor for development and testing purposes. The technology can be modified for other naturally aspirated off-road vehicles used in agricultural, construction, and power generation.

The Propane Education and Research Council (PERC), Texas Alternative Fuels Council, John Deere Product Engineering Center and Texas Railroad Commission were also involved in the development program. The tractor is undergoing field testing under real-world conditions, initially for park maintenance with the city of San Antonio. Operators will assess the tractor's performance and reliability as well as provide feedback and real-world fuel-use data.