Heat Balance Provides Insight into Modern Engine Fuel Utilization

HEAT BALANCE STUDIES were conducted on a 1975 production 5.74ℓ V-8 and an experimental 3.69ℓ V-6 to determine sources of fuel economy differences when they were installed in a vehicle. Heat balance results, friction and fuel economy were explored during dynamometer tests simulating road load. Comparisons were made with and without certain emission control features.

With comparable calibrations, the road load indicated efficiency was nearly the same for each engine as it would be installed in a vehicle with an appropriate axle ratio. The results suggest that engine friction and not combustion efficiency accounted for the major fuel economy difference.