A Brief Guide to Diesel Fuel

Diesel fuel is the backbone of our logistics networks, backup generator power, and many other industrial and home use applications. It fuels the majority of big rigs on the roads, many personal automobiles, boats, and even locomotives. It is one of the distillate fuels produced from crude oil. It recently lost its dirty reputation because the Environmental Protection Agency (EPA) passed laws in 2015 requiring distillers to lower the sulfur content of diesel to reduce the pollutants in the air. The EPA has also passed laws that require automotive manufacturers to install Diesel Particulate Filters (DPFs) that reduce emissions by 90 percent or more.

How Does Diesel Fuel Run Engines?

The diesel engine uses compression-ignition to burn diesel fuel. It was invented by Rudolf Diesel in Germany. Before this time, gasoline and diesel were considered to be waste products of the fuel cracking process. Kerosene was the product in chief demand from companies like Standard Oil for heat and lamps.

The compression-ignition mechanism that powers diesel engines is based upon the physics of compressing a fuel/air mixture until it is hot enough to self-ignite. When an engine operates in this manner, it does not need spark because the compression produces just enough heat to combust the fuel/air mixture.

The science of determining calculating reactions like efficient fuel combustion is called Stoichiometry. When fuel is mixed with the ideal air mixture and compressed, it would be operating at the ideal stoichiometric ratio. The stoichiometric ratio for diesel is 14.5 parts of air for every 1 part of fuel. The parts can be liters, gallons, metric tons, or what have you.

The compression-ignition process is more efficient than spark-ignition systems that run on gasoline. Manufacturers are now trying to imitate the compression-ignition of the industrial injection diesel engine, in part, by using perfectly timed direct injection.

Direct injection directly injects the fuel into the combustion chamber instead of the head. But, like a diesel engine, the fuel is burned more completely because it is injected into the engine when the pistons have fully compressed the combustion chamber. Other attempts to create a gasoline engine without spark have yet to produce a production motor. Because diesel engines are more efficient, they are known for increasing or even doubling the fuel economy of a vehicle.

What Are the Power Differences Between Diesel and Gasoline Engines?

The big noticeable difference between a diesel engine and a gasoline engine is the powerband. Most diesel engines have power in the low-end torque band and not in the horsepower range. The torque range is the low-end twisting force of the engine and capacity to haul heavy loads. The horsepower is its power to get up and go spontaneously. For this reason, most people see diesel vehicles as sluggish and prefer gasoline for snappy throttle response and performance. However, when it comes to work trucks, hauling, fuel economy, and durability, diesel is hard to compete against.

Diesel engines are also built better than most gasoline engine. Because they have to endure greater pressures, the parts are usually beefed up. Try one for yourself and compare.