Kohler 3403TCR SCR; Compact Commercial Workhorse
Kohler’s Compact Turbocharged Commercial Workhorse
Gone are the days of smoking, overweight, underpowered diesel engines. Today’s oil-burners must be lighter, cleaner, and more powerful. These modern diesels have strict emissions and fuel economy standards placed on them that require manufacturers to be creative in order to remain competitive in the marketplace. But the stringent standards for new engines make it difficult for preexisting powerplants to remain relevant.
Kohler understands the tougher requirements and addresses them with the “Best Fit” line of Kohler direct-injection engines. KDI powerplants are smaller and feature equally compact emissions equipment, creating the best-fitting, most versatile units possible.
The KDI3403TCR-SCR is the largest engine in the KDI group of small diesels, and it is the highest-output engine the company produces. It is designed for heavy-duty commercial applications that require robust power and torque while maintaining good fuel economy. The KDI3403 is able to produce 134 hp and 369 lb-ft of torque, while only displacing 3.4L. The smaller displacement and healthy performance output put it in direct competition with larger engines and make it ideally suited to such vehicles as tractors and wheeled loaders. Maximum torque also comes in at just 1,400 rpm, allowing the engine to do demanding work while conserving fuel.
Along with the good performance numbers, the KDI3403 meets EPA Tier 4 and EU Stage IV emissions standards without using a diesel particulate filter. Its ability to meet these standards and still produce good power comes from the integration of different technologies. Better combustion starts with Kohler’s innovative high-pressure, common-rail-injection system that operates at 29,000 psi and uses G3S solenoid-type injectors. The injectors are centered vertically between the two intake and two exhaust valves for each cylinder. With this orientation, fuel is precisely metered and injected directly onto pistons that feature combustion bowls specifically designed for better atomization and mixing with air coming through inlet ports that are shaped for promoting optimal combustion. A mechanical-rotary pump pressurizes the fuel for the injection system.
A geardriven camshaft—operated via hydraulic tappets, pushrods, and rockers—drives each of the four valves per cylinder. Airflow is maintained by a fixed-geometry turbocharger tuned to minimize turbo lag and produce maximum air volume. The turbo’s charged-air cooler is integrated into the radiator.
The KDI3404’s engine block is designed with a combination of bedplate (supporting frame/sub-crankcase) and crankcase, which creates a strong foundation that helps reduce noise and vibration. It also houses the counter-rotating crankshaft that is used to make the engine run smoothly.
An electronically controlled EGR valve optimizes the recirculation of exhaust gases through the water-to-air heat exchanger. The EGR valve is installed on the hot side of the system to prevent the valve from seizing, improving reliability. Exhaust gas is routed across the cylinder head for preliminary gas cooling before entering the EGR valve. This helps to reduce the overall size of the unit.
Along with the EGR, the engine features a selective catalyst reduction system that houses the diesel oxidation catalyst, the mixing pipe (for diesel exhaust fluid), and the SCR, which all work to reduce NOx emissions. With the addition of a DPF for meeting EU Stage V emissions standards, the compact SCR system is being engineered with the future in mind.
SPECIFICATIONSEngine: Kohler KDI3403TCR-SCR
Displacement: 3.4L (205 ci)
Engine Layout: I-4
Valvetrain: Four valves per cylinder
Bore x Stroke: 3.8 x 4.6 inches (96 x 116 mm)
Head material: Cast iron
Block material: Cast iron
Power: 134 hp
Torque: 369 lb-ft
Emissions: EPA Tier 4/EU Stage IV
Induction: Fixed-geometry turbocharger
Exhaust: Cast iron
Cooling System: Oil- and air-cooled
Fuel System: High-pressure common-rail direct injection
Lubrication System: Wet sump
Lubrication Capacity: 16.5 quarts (15.6 L)
Dry Weight: 868 pounds (394 kg)
Length: 28.2 inches
Width: 22.8 inches
Height: 32.1 inches