Over the past couple of months, we’ve learned that two major off-highway engine manufacturers have been able to meet Tier 4 Final emissions standards while scrapping some of the pollution control equipment we’ve all grown to hate. This time, it’s John Deere’s turn in the spotlight. The company’s new PowerTech PWL 4.5L engine, designed for 75hp to 140hp applications, will debut without a diesel particulate filter (DPF).
How They Did It
Deere was able to get around using a DPF by optimizing internal combustion efficiency, thanks to the PowerTech PWL 4.5L’s newly refined piston design, higher-flowing turbocharger and, of course, its high-pressure common-rail fuel system. Increased injection pressures and more precise injection events and fuel quantities mean a cleaner burning engine and less particulate matter to deal with. On the flip side (and knowing that hotter, cleaner combustion equals more NOx emissions), Deere uses an improved selective catalytic reduction system (SCR) to convert NOx into carbon dioxide and nitrogen. In addition to SCR, the PowerTech engine will also have a diesel oxidation catalyst (DOC) and cooled exhaust gas recirculation (EGR) technology. The company calls this its Integrated Emissions Control system.
The Benefits of No DPF
According to John Deere, eliminating the DPF reduces cost while making engine packaging easier for its customers. For serviceability, being void of a DPF rules out a potential failure point within the emissions system, as there is no particulate trap to clean or replace, and no extra fuel is consumed during regeneration intervals. While on the subject of fuel consumption, Deere also states that diesel exhaust fluid (DEF, for the SCR system) consumption will be just 1 to 4 percent of diesel fuel consumption on all its Tier 4 Final-compliant engines. This means the DEF tank’s size can be much smaller (taking up less vital space in each application), longer DEF filter service intervals can be observed, and operators will have lower bulk storage requirements.
Once again, we’re hopeful that the simplification of emissions control devices on off-highway diesels makes its way into the on-highway segment in the future. Higher injection pressures, dead-on injection events, and perfected SCR technology are the wave of the future, and we’re constantly seeing more and more advancement in all of these areas. If this trend continues, we could even see DPFs and EGR go away altogether one day.
Engine: John Deere PowerTech PWL 4.5L
Block: Cast iron
Head: 4-valve, cast iron
Bore and Stroke: 4.2 x 5.0 inches
Horsepower: 75 hp to 140 hp (depending on application)
Induction: Single wastegated, fixed-geometry turbocharger, air-to-air intercooled
Fuel System: High-pressure common-rail
Emissions Compliance: EPA Tier 4 Final/European Union Stage IV
Emissions Equipment: EGR/SCR