TORQUE:
The definition of torque is twisting force and the duty of a marine engine is twisting a propeller. There are two different types of torque curves to be understood when comparing marine engines.
1. A Peak Style Torque Curve gives high horsepower and torque measurements for a short duration (500-700 rpm). On the high and low side of the optimum torque range such as wide open and cruising rpm ranges, the engine is not in its optimum torque range, therefore the engine is operating with a minimum efficiency caused by overfueling.
2. A Broad Style Torque Curve gives high horsepower and torque measurements for a long duration (approx 2500 rpm). At planing, cruising and wide open rpm ranges, the engine is operating within the optimum torque ranges resulting in maximum efficiency through a wide range.

All Chief designs have broad torque curves because the advantages of this method allow maximum efficiency throughout the whole rpm range, thus increasing the practicality and performance of the marine engine. Engines having a steep power curve give you a high horsepower rating but their power declines sharply when brought back to cruising range.

FUEL EFFICIENCY:
Engines must be designed with components that favor each other such as induction, combustion and exhaust systems. Many times engine designs are misfitted and decrease engine endurance. For example, if an engine is over fueling or running lean in certain RPM ranges due to incorrect component profiles, then detonation, lubrication dilution, spark plug fowling, rough operation and low power output cause premature part failure.

Chief Engines utilize Brake Specific Fuel Consumption (BSFC) numbers. BSFC is the volume by weight of fuel used by an engine to produce one horsepower for one hour. This measurement is used in several ways: allows proper precision tuning, prompts research and development, confirms proper component