Why does a diesel engine operate more economically than a gasoline engine?
A. There are two basic reasons why a diesel engine operates so much more economically than a gasoline engine. First we must take a look at the fuels themselves. Diesel fuel is much heavier than gasoline with densities of around 0.85 for diesel and about 0.74 for gasoline. The higher density of the fuel the higher the heating value. This translates to a net heating value of about 130,000 BTU per gallon for diesel, and about 115,000 BTU per gallon for gasoline. Therefore, diesel has about 12% more energy per gallon. Next, we look at how the fuel is combined with air and ignited. There are some fundamental differences: A gasoline engine mixes the ambient air and fuel before drawing it into the cylinders. The diesel forces the air (turbo charger) into the cylinder, compresses it, and then injects the fuel into the cylinder. The gasoline engine ignites the fuel/air mixture with a single spark. The resulting flame front grows during the compression and power cycles. The diesel engine uses th
A. There are two basic reasons why a diesel engine operates so much more economically than a gasoline engine. First we must take a look at the fuels themselves. Diesel fuel is much heavier than gasoline with densities of around 0.85 for diesel and about 0.74 for gasoline. The higher density of the fuel the higher the heating value. This translates to a net heating value of about 130,000 BTU per gallon for diesel, and about 115,000 BTU per gallon for gasoline. Therefore, diesel has about 12% more energy per gallon. Next, we look at how the fuel is combined with air and ignited.
