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Gas or Diesel

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Posted August 1, 2011 by admin in Articles
diesel

For the most part, the answer to this question depends on your background and how you want to go down the road. The majority of novice MotorHomers are most comfortable with the gasoline powered MotorHome. The obvious reason is that almost everyone is familiar with the gasoline-powered engine. “Diesels areok, but . . . .” “I know how a gas engine works and I?m not familiar with the diesel engines.” “Diesels are smelly!” “Gas is safe.” Either engine is okay, but before you make a decision let me help you understanding the advantages and disadvantages of both.

Power and Engines

The traditional gas engine has been around since before rubber wheels went around. Both gas and diesel engines are internal combustion, of course, and get their power from a fuel source. There is less power (heat) in gasoline than there is in diesel. However, the more heat generated by the fuel the more substantial the engine components must be. And, the excess heat has to be carried away by the coolant. This means that the gasoline engine does not have to be as heavy duty as the diesel engine. The more substantial diesel engine carries a higher cost. All MotorHome gas engines are four cycles (intake, combustion, power, and exhaust). Most of the diesel engines are the same. The more ambient (cool) air available the more power the engine can make with the available fuel. Altitude also affects the availability of air for combustion. An engine equipped with a turbo charger can make up for altitude air loss and can give immediate throttle response in almost any situation. Both types of engines can be equipped with turbo chargers. Almost all MotorHomes with diesel engines have turbo chargers. Gasoline powered MotorHomes will have to be equipped with turbo chargers as an after market item.

Cooling

Typically gasoline powered MotorHomes are front engine driven. The engine is located under the dash and somewhere between the driver and passenger seat area. The radiator is in front of the engine. Air flows through the radiator and across the engine carrying heat away. The area that contains the front engine is limited in size, however, due to its location. These engines sometimes suffer from heat buildup due to inconsistent airflow over the engine resulting in fuel vapor lock, extreme exhaust header temperatures and peripheral component failure. After market engine components can sometimes relieve these problems. Most MotorHomes with diesels are called pushers because the engine is in the rear. Cool air flows through a rear-facing radiator or from the side through a side-facing radiator. A hydraulic pump providing a constant fan speed regardless of engine RPM drives most side radiator fans.

Fuel Economy and Engine Life

Fuel economy for a gasoline powered MotorHome will depend on the MotorHome gross vehicle rated weight, driving habits and conditions and will probably range from 5-9 mpg depending on how hard the engine has to work. Fuel mileage for a diesel-powered coach will range from 8 to 14 mpg depending upon operating conditions. Large bus conversions with 2-cylce diesel engines may get less fuel economy.

RPM operating range of a gas powered MotorHome is almost always higher than a diesel engine. Engine life, with prescribed care, moderately loaded in terms of engine demand (hot weather, mountains), can be typically in the 70-90,000 mile range. This means that if you plan to take your MotorHome on numbers of extended trips, you are going to reach the wear-out point fairly quickly with a gas engine. MotorHome owners who are out for a weekend or a yearly vacation may drive 4-5000 miles a year. Those that are full timers may go 10-15,000 miles a year. There are exceptions. My wife and I both work full time jobs and managed to put 13,000 miles on our Patriot in the past year. Engine life for a diesel MotorHome, on the other hand, can easily top 250-500,000 miles when cared for in accordance with the manufacture?s recommendations. Basic rules in caring for diesel engines are: clean fuel, clean oil, clean air, clean coolant. Manufactures recommended schedule for periodic maintenance is the most important part of extending your engine life.

Most gasoline powered MotorHome chassis? are in the 16-21,000lb capacities and are between 18 and 38 ft in length. The greater the length, the lower the payload capacity. Payload means the amount of weight you can load into your MotorHome above its dry weight. The sum equals the vehicle gross weight. In other words if your MotorHome has a dry weight of 22,000 pounds and has a gross vehicle weight rating of 23,000 pounds your payload is 1000 lbs of people, food, water, etc. Typically, diesel MotorHomes have a stronger chassis in order to accommodate greater length and larger payloads—28 to 40+ feet. Also, since the diesel engine has a longer life, the chassis also needs to be more durable.

Making aDecision

So, what?s the bottom line here? Again, it mostly boils down to how you want to go down the road. If money is an issue, as it is for most of us, you may have to make your choice according to what you need instead of what you want. Both types are adequate means of getting out and enjoying the country, but diesels are more expensive. A diesel pusher will cost somewhere between $20,000 and $30,000 more than a gasoline powered coach of the same size. High line coaches are of course diesel powered and more expensive. Generally speaking, a gasoline engine is not practical if the coach is over 23,000 pounds. So, if you need a larger coach you will need to go with a diesel engine. After a particular weight class the gasoline engine just isn?t practical. In my opinion, this would be the case in classes above 23,000 lbs. For a diesel engine, a good rule of thumb is that you need a minimum of 10 horsepower for each 1000 pounds of GVRW. The absolute minimum diesel engine horsepower you would need for a MotorHome in the 23,000 pound class is 230. Engine torque is an important issue. A 230hp diesel engine will give you much more “staying” power than a 230hp gasoline engine.

Other issues related to engines are transmissions and torque—the right application for the intended purpose. Watch this site for future articles OR check out my consulting services to get specific answers to specific questions.

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