Diesel Engines


Diesel engines are internal combustion engines that work mechanically the same way as their gasoline counterparts. In modern times they are four stroke engines that share the same major components of a gasoline engine. The main difference is the fuel and combustion process. In a gasoline engine, fuel is sprayed into the cylinder with a ratio of air and then is ignited by a spark. Diesel engines rely upon compression to heat the air which enters the cylinder to ignite the fuel/air mixture. Gasoline engines rarely have compression ratios greater than 11:1 so lower octane fuels can be used without engine detonation occuring, diesel engines run compression ratios usually between 15:1 and 25:1 to compress the air to a temperature that will ignite the fuel. In a gasoline engines intake stroke an air/fuel mixture is drawn into the cylinder head. In a diesel engine air is aspirated alone on the intake stroke, then the cylinder is sealed to allow the air to compress and heat to temperatures around 1400 degrees fahrenheit. As the diesel engines piston approaches top dead center, a fuel oil mix is sprayed into the cylinder which is already hot enough to ignite the fuel. The rest of the four-cycle process is the same as that of the gasonline engine.


Diesel engines do have one foe. Cold weather presents a problem for a diesel fuel'd vehicle because the mass of the cylinder head and block absorb the heat needed to ignite fuel. This is why if you have ever ridden in a diesel powered vehicle that was being started cold, you more than likely had to wait with the ignition turned on for a while until turning over the engine. Most diesel engines use a device called a glow plug that helps ignite the fuel. A glowplug is no more than a small heat device. Other engines may use resistive grid heaters in the engines intake manifold to warm air as it enters the engine to help the combustion process.

Why use diesel to power an engine? Diesel engines are more fuel efficient than gasoline motors of their same power. The common marketed number is that new turbodiesel engines are 40% more fuel efficient than gasoline motors of their same power. In todays market with fuel prices sky rocketing this is important allowing consumers to get more miledge to their dollar.

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