CUMMINS TURBO DIESEL ENGINE (2003 Ratings)
"Cummins Turbo Diesel"
Figure 1: Cummins Turbo Diesel Engine
49-State High Output Engine
49-State Standard Output Engine
California Standard Output Engine
The high-output Cummins Turbo Diesel engine with manual transmission gives Ram the highest GCWRs (Gross Combined Weight Rating) in the heavy-duty pickup segment. It is rated at up to 23000 pounds GCWR. Rear axle ratios are now 3.73 or 4.10
GCWRs have also increased for most other models as well. Rear springs have been
selected to keep the tail gate height below 57.5 inches (1460 mm) to accommodate
more fifth-wheel trailers than the 2002 models did.
Cummins Turbo Diesel Engine
Extensive redesign of the Cummins Turbo Diesel engine included major emphasis on minimizing traditional diesel engine noise. Noise level of all versions of the engine have been reduced substantially and now approach those of gasoline engines. The most notable areas of noise reduction are at idle, especially when the engine is cold, and under light-load acceleration and cruising conditions.
The major contributing factor to combustion noise reduction is new high-pressure common rail electronic fuel injection. This system uses pilot injection, the injection of a small amount of fuel that starts combustion, before the main, power-producing, fuel charge is injected. This has the effect of smoothing out combustion pressure in the cylinder, which is the primary source of low-speed noise in diesel engines. In addition to the use of pilot injection to smooth combustion pressure, the fuel injection calibration -
For California, Ram Pickups powered by the Cummins Turbo Diesel engine include an underfloor oxidation catalytic converter as in 2002. For the other 49 states, the exhaust need no after-treatment to meet emission standards
Extensive improvements to the proven Cummins diesel engine for the 2003 model year provide
The Cummins engine continues with both Standard and High Output versions. Starting in January 2003, the High-Output engine will be available with automatic transmission.
Figure 2: Cummins Turbo Diesel Engine
Power and Performance
The high-output engine, which is not available in California, produces nearly 25 percent more peak power and 10 percent more torque than the 2002 version. The Standard-Output engine available in 49 states produces over 6 percent more power than in 2002. A Standard Output California-version is also available.
All versions of the Cummins engines feature a 400 rpm-wider maximum torque range than in 2002 - 200 rpm below and 200 rpm above the previous range. The maximum torque occurs 400 rpm lower than the GM Duramax, and 200 rpm lower than the Ford Power Stroke. These engines also produce 20 percent more torque at 1000 rpm, and 10 percent higher clutch engagement torque than their predecessors. These performance improvements result in:
49-State High Output Engine
49-State Standard Output Engine
California Standard Output Engine
The engine responds faster to changes in accelerator pedal position as a result of Cummins' proprietary engine control system and a state of the art common-rail electronic fuel injection.
A gear driven injection pump delivers a fuel to the rail that is electronically controlled to optimize fuel pressure at the individual injectors. The system provides injection pressures up to 23,200 psi (1600 Bar) that are less dependent on engine speed than the traditional pump-line injection system. The result is cleaner combustion and higher low speed torque with better vehicle response and acceleration.
Cummins' controls and the electronic fuel injection ensures that the engine combines optimum fuel economy and performance with emission control capabilities to meet increasingly stringent emissions regulations. In addition, the common-rail architecture and electronic controls are capable of providing new features, such as multiple injection pulses, and independent control of injection pressures. This provides both noticeably quieter operation and improved cold start capability..
Both engines share a higher compression ratio that contributes to the increased power and torque. For the standard-output engine, the increase to 17.2:1 is almost one full ratio.
Figure 3: High-Pressure Common-Rail Fuel Injection System
Improved combustion and fuel systems management, and a higher compression ratio provide better cold starting capability at extremely cold temperatures. Benefits include:
For cold starting, the engine continues to use an electronically controlled intake air heater grid, mounted at the inlet to the intake manifold, that is inherently more reliable than the glow plugs used in competitive engines.
The Cummins Turbo Diesel engine is renowned for its durability, being used in commercial medium-duty and heavy-duty applications worldwide. The simple inline-six cylinder design has up to 40 percent fewer parts than competitive V-8 diesel engines. And the Cummins engine has an average life to overhaul of 350,000 miles, compared to 250,000 for competitive engines. Because of its longevity, the Cummins engine is rated as a "medium-heavy duty" engine, compared to the "light-heavy duty" designation for GM Duramax and Ford Power Stroke diesels.
All versions of the engine use valve seat inserts for added durability. And the High-Output engine employs gallery cooled pistons -internal oil passages in the pistons that lower piston operating temperatures for longer life at the higher power levels this engine produces.
The new self-priming fuel system enables fast and easy re-starts after routine fuel filter changes, and avoids manual priming and costly road service calls if the vehicle runs out of fuel.
The redesigned combustion system reduces NOx and hydrocarbon emissions by 25 percent on California. For the 49-State engines, power and performance are enhanced while still meeting current emissions regulations. The new controls and fuel system technology also enable the engines to meet increasingly stringent future emissions standards.
The redesigned engine provides the following key serviceability improvements:
In normal service the oil change interval increases from 7,500 to 15,000 miles; the trailer towing (severe service) oil change interval also increases - from 3,750 to 7,500 miles. Soot reduction resulting from cleaner combustion is the primary enabler for the extended oil change intervals. Oil change capacity remains at 12 quarts including oil in the filter.
Enhanced oil filter accessibility results from relocating air conditioning refrigerant lines and coolant lines. The addition of flutes to the filter housing allows use of a cap-style filter wrench for easier removal and installation.
The new fuel system enables fast and easy re-starts after routine fuel filter changes, and avoids manual priming and costly road service calls if the vehicle runs out of fuel.
All accessories are driven by a single serpentine belt with automatic tensioner, whereas the power steering pump was previously gear driven. Accessory drive ratios have been optimized for improved performance over a wide range of conditions.
Figure 4: Cummins Turbo Diesel Engine Accessory Drive System
2500 and 3500 Ram Pickups with gasoline engines use the same air cleaner and filter element as the 1500s. With these engines, the air cleaner inlet extends through a shield that separates the outer fender area from the engine compartment to provide cooler air to the engine. With diesel engines, a larger air cleaner assembly and filter are used because of the higher air consumption of these engines. As in 2002, the air cleaner housing includes a Filter Minder device to help determine when the filter needs to be replaced. Both air cleaner housings mount on the frame rail in the right front corner of the engine compartment.
The 48RE automatic transmission will be optional on 2500 and 3500 series with both
Cummins diesel engines and with the 8.0-liter gasoline engine beginning in January 2003. It is a beefed up version of the 47RE automatic transmission, which it replaces. Extensive internal modifications give it the torque capacity and durability required to work with the redesigned High Output Cummins diesel engine. This is the first automatic transmission available with the High Output engine. The internal modifications also give the transmission a design life of 150,000 customer-equivalent miles. Contributing to the durability and long life is electronic torque management - limiting engine torque build up when initiating acceleration from a stop. The 48RE transmission retains all the features of the 47RE, including the electronically controlled governor, and the same gear ratios.
For states that require vehicles to meet the California Emission Standards, the Cummins Turbo Diesel exhaust system includes a single underfloor catalytic converter. For those states which do not require vehicle to meet this standard the converter is replaced by an exhaust resonator.
Full-width radiators are standard with Cummins Turbo Diesel and 8.0-liter MagnumŽ V-10 gasoline engines due to higher cooling demands. In these cases, the air-conditioning condenser, where used, mounts ahead of the radiator in a conventional manner. All models with the new 5.7-liter HEMIŽ MagnumŽ V-8 engine have the radiator and air conditioning condenser mounted side-by-side, as on all 2002 models. Benefits of this arrangement remain the same: reduced fan power loss and quieter fan operation.
An electronically controlled viscous fan drive is included with the Cummins Turbo Diesel engine. It reduces noise and fuel consumption, compared to the prior thermostatically controlled viscous drive system, when added cooling air provided by the fan is not needed. This form of control also allows the use of a larger fan than in the past to maximize cooling under extreme conditions. The fan can consume up to 25 horsepower at high rpms. The PCM operates a solenoid valve on the fan drive that controls flow of the viscous material, determining when fan engages and disengages and also how fast it turns. Coolant temperature and air conditioning refrigerant pressure are the primary inputs that determine fan operation. Previously, only underhood air temperature was used to determine whether the fan ran or not. Electronic control also enables electronic diagnostic capabilities for fan drive operation. Viscous coupling of the fan to the engine continues to limit fan speed at high engine speed.
The Cummins Turbo Diesel engine for 2003 is noticeably quieter than in prior model years. The noise levels of all versions of the engine have been reduced and approach those of gasoline engines. Noise is lower across the entire operating speed range, especially at idle and during cruise conditions.
The following features contribute to noise reduction: