2-valve cylinder head
Cross-flow head design provides excellent breathing from a lower-cost 2-valve cylinder head.
Mechanical rotary fuel pump
The timing and fuel injection pressures are optimized to maximize performance and fuel economy at a given rated speed (4.5L).

Mechanical unit pump (MUP) fuel system

This system uses camshaft driven MUPs, connected to the injectors by a short fuel line. This short fuel line between the unit pumps and the injectors helps to alleviate after-injection, secondary injection, and other injection abnormalities (2.4L).
Fixed geometry turbocharger
Fixed geometry turbochargers are precisely matched to the power level and application.

Naturally aspirated
In naturally aspirated engines, the combustion air is drawn into the cylinder when the piston moves down. The amount  of air is limited by the displacement of the engine (2.4L).
Turbocharged
In turbocharged engines, the air is pre-compressed. Due to the higher pressure, more air is supplied into the combustion chamber allowing a corresponding increase in fuel injection, which results in greater engine output (2.4L and 4.5L).
Air-to-air aftercooled
This is the most efficient method of cooling intake air to help reduce engine emissions while maintaining low-speed torque, transient response time, and peak torque. It enables an engine
to meet emissions regulations with better fuel economy and the lowest installed costs (4.5L).
Compact size
Mounting points are the same as Tier 2/Stage II engine models.

Engine performance
• Lower-rated speeds available for reduced noise and improved fuel economy
• New power bulge feature (4.5L)
• New higher-peak torque speed
Additional features
• Self-adjusting poly-vee fan drive
• Forged-steel connecting rods
• Replaceable wet-type cylinder liners (4.5L)
• Either-side service
• 500-hour oil change
• Optional final fuel filter with water separator  and water-in-fuel sensor (4.5L)
• Optional balancer shafts

PowerTech M 2.4L engines
• Power range:
4024T: 36 – 37 kW (48 – 49 hp)
•Improved unit pumps
•Improved governor serviceability
•Improved timing cover access

PowerTech M 4.5L engines
• Power range:
4045T: 56 – 63 kW (75 – 85 hp)
4045H: 74 kW (99 hp)
• New power bulge feature — up to 1%
• Higher-peak torque speed
• World-class fuel economy
• Lower-rated speeds to reduce noise and improve fuel economy
• Cold-starting capabilities that meet or exceed Tier 2/Stage II
• Maintain Tier 2/Stage II compact size and mounting locations
Tier 3/Stage III A PowerTech M 4.5L engines

(Source – http://www.deere.com/common/docs/products/equipment/industrial_and_agricultural_engines/specs/Spec_Guide_update.pdf)