Diesel Vs. Gas Motor

An internal combustion engine combines oxygen with a fuel to cause an exothermic reaction that drives mechanical parts. Though such a design can use a number of different fuels, the two most common fuels in use today are diesel and gasoline. As these fuels have substantially different chemical compositions, they require different types of engines in order to function properly. Both gasoline and diesel engines have their advantages, and the question of which design is superior is the subject of an ongoing debate.

History

• German inventor Nikolaus August Otto was the first person to successfully make an operating internal combustion engine. He built his first four-stroke engine in 1876.

  The first gasoline-powered automobile was also the first true automobile, created by Karl Friedrich Benz in 1885. This design had poor performance and was difficult to operate and repair. For this reason, electric motors were more popular among early automobile owners, and it remained so until Henry Ford developed the assembly line and made gasoline-powered cars available at low prices. This led to the general popularity of gasoline-powered engines in North America. Though other types of gasoline engines exist, such as two-stroke, six-stroke and rotary (Wankel) engines, Otto's four-stroke engine remains the most widely used.

  The diesel engine gets its name from its inventor, German scientist Rudolf Diesel. Knowing that compressing a gas would cause it to become hotter and have more of a tendency to engage in chemical changes, he sought to develop an engine that would use the actual pressure of the air involved to cause combustion. He built his first working prototype in 1893.

Function

• Otto's engine used four strokes of action to complete its purpose: intake, compression, combustion and exhaust. During the intake phase, it pulls in air and fuel. In the compression phase, it mixes and compresses them together to make them more combustible. In the combustion phase, a spark plug causes the fuel-air mixture to explode, which is what pushes the piston and powers the engine. In the exhaust phase, the piston pushes the smoke resulting from the reaction out of the engine.

  In diesel engines, there is no spark plug. Instead, during the compression phase, the fuel-air mixture becomes hot enough that combustion occurs naturally.

  Both types of engines normally use multiple pistons all operating at different strokes. This is because the only stroke in which a piston actually exerts positive force is the third stroke--in the other strokes, it actually causes friction that slows down the engine. By operating at different strokes, the various pistons power each other through the other strokes.

Benefits of Gasoline

• According to "Truck Trend Magazine," gasoline engines generally have an advantage over diesels in horsepower. Simply put, this means that they accelerate faster. This is why most race cars have gasoline engines rather than diesel engines.

  Another advantage of gasoline engines is the availability of fuel. In North America, not every fueling station open to the public carries diesel, but virtually every one of them will carry gasoline.

  Gasoline engines are also cheaper than diesel engines. The same light truck model will cost more with a diesel engine than with a gasoline engine. Also, the normal maintenance such as oil changes is cheaper for gasoline engines than for diesel engines.

  Finally, since gasoline engines have spark plugs that cause combustion, they perform better in cold weather. When they are cold, diesel engines sometimes cannot start, since the fuel-air mixture cannot reach the necessary temperature on its own.

Benefits of Diesel

• While gasoline engines have more horsepower, diesel engines have more torque. This means that they can perform better under stress--such as when they are pulling a heavy payload. This is why freight trucks, heavy industrial trucks and construction vehicles such as bulldozers generally use diesel.

  Another advantage of diesel-powered engines is that they are more efficient. Diesel fuel has a higher energy density than gasoline, so it takes less fuel to travel the same distance. However, this may not be much of a benefit if diesel fuel prices are higher than gasoline prices anyway.

  When it comes to service and maintenance, though simple upkeep is cheaper for gasoline engines, diesel engines are often cheaper to maintain in the long run. This is because they respond so much better under stress, causing them to wear out much more slowly than gasoline engines. In general, diesel engines can go about three times as far as gasoline engines before needing serious maintenance.

Misconceptions

• Because most consumer vehicles in North America use gasoline rather than diesel, many believe that diesel engines are not suitable for smaller vehicles. However, this is not the case. Many consumer vehicles in Europe use diesel rather than gasoline, and such diesel-powered consumer vehicles are becoming increasingly popular in North America due to their efficiency benefits.

Warning

• Mixing a little diesel with the gasoline in a gasoline-powered car can be beneficial, because it, being an oil, helps to break down oil-based gunk in your fuel system and engine. However, putting large amounts of gasoline in a diesel engine or diesel fuel in a gasoline engine can cause serious problems. In general, it is not good to put any fuel into your car or truck except for what it is designed to take.