G3500 Engines Caterpillar

Air/Fuel Ratio

The correct air/fuel ratio is important for the following considerations:

• Margin of detonation

• Control of emissions

• Achieving optimum service life for the engine

If the air/fuel ratio is not appropriate for the fuel and the operating conditions, a failure of the engine may occur. The service life of the turbocharger, the valves, and other components may be reduced.

Any changes to the air/fuel ratio may affect the exhaust emissions. After adjustment, use an emissions analyzer to measure the exhaust emissions. Ensure that the engine is in compliance with local regulations for emissions.

Fuel Supply Pressure

The engine can operate with a minimum fuel pressure of 10.3 kPa (1.5 psi). Fluctuations of the fuel pressure prior to the fuel control valve will have a negative effect on the stability of the engine rpm. Control of emissions can also be affected. Ensure that the engine has a stable fuel pressure of ± 0.25 kPa (± 0.04 psi).

Fuel Temperature

The system is designed for fuel temperatures less than 60 °C (140 °F). For optimum performance, the maximum recommended differential temperature for the fuel and air is 2.8 °C (5 °F).

Temperature of the Air Supply

Change in the temperature of the air supply affects the air/fuel ratio. In addition to seasonal changes, the air temperature changes overnight. Control of the temperature in the engine room will help to maintain the air/fuel ratio.

To avoid hot air from a generator, use ducting. For more information, refer to Application and Installation Guide, LEKQ7250, "Air Intake". Consult your Caterpillar dealer for assistance.

Refer to the performance specification for the ambient temperature derate.

Exhaust Bypass (Wastegate)

The engine has an adjustable exhaust bypass valve. This valve controls the flow of exhaust gas to the turbine wheel to maintain the desired boost pressure. Excessive boost pressure can result in overloading of the engine, overheating, detonation, and turbocharger surge. For the adjustment procedure, refer to the Systems Operation/Test and Adjust manual.

Oil Consumption

The rate of oil consumption is called Brake Specific Oil Consumption (BSOC). The unit of measure is grams per brake kilowatt hour or pounds per brake horsepower hour. The BSOC depends on the engine model, the aspiration, the operating load, and the oil that is used. For information on calculating the BSOC, refer to Engine Data Sheet 96.2, LEKQ4028, "Oil Consumption Data".

Table 1 lists the normal mid-life BSOC for G3500 Engines under the following conditions:

• Load factor of 100 percent

• Maintenance is performed according to this Operation and Maintenance Manual, "Maintenance Interval Schedule" (Maintenance Section).