Niagara Gazette — Diesel engines use direct fuel injection into the combustion chamber. Diesel fuel is injected directly into the engine’s cylinder when the piston is at the height of travel (TDC) of the compression stroke and thus, the chamber is ready to ignite the fuel and initiate the power stroke.
Gasoline engines use an extremely rich air/fuel mixture (which is highly volatile in the presence of an ignition source) to achieve cold starting.
When a diesel engine is cold, the compression stroke may not raise the air to a temperature hot enough to ignite the fuel; therefore a glow plug or other means are used to prepare the combustion chamber for ignition. A glow plug is an electrically heated device that helps ignite the fuel when the engine is cold. On diesel engines that have an ECM, (Engine Control Module) the ECM reads air temperatures and if it senses that its cold outside, it retards engine timing and sprays fuel at a later time than at TDC. This makes for greater compression of air, thus raising combustion chamber temps and making cold starting easier. Additionally, block heaters are used to keep the engine’s cooling system warm, this keeps the oil in the crankcase from gelling up and creating higher resistance to the crankshaft as it turns ensuring the engine cranks fast enough to start. Finally, diesel fuel during cold weather tends to gel up, creating resistance to flow, it is recommended you use anti-gel compound to ensure the fuel does not stop flowing through the delivery system. This anti gelling compound is added to the fuel tank.
The Difference Between the Fuels
When crude oil is processed at refineries, it is separated into several different kinds of fuels, including gasoline, jet fuel, kerosene and diesel. Diesel fuel is heavier and oilier than gasoline. Plus, diesel fuel has a higher energy density than gasoline.