At the most basic level, modern car engines work on the principle of four simple strokes: intake, compression, power, and exhaust. Repeat this cycle enough times per minute, and it has the ability to make any gear-head grin. Whether diesel or gasoline powered, the four engine strokes are the same, but there are key differences as to how the strokes are executed.
Engine Operation Differences
For gasoline engines, the intake stroke generally involves pulling air and fuel into the combustion chamber. At this point, a diesel engine is only pulling in air. Next is compression, where both engine types squeeze down the air into a small pocket. Ignition is controlled separately for each fuel type. Gasoline engines use a spark plug to time and start the power stroke. This small arc of electricity ignites the air fuel mixture and the powerful blast forces the piston down, churning out that highly craved horsepower. A diesel engine, on the other hand, only has a pocket full of hot air before the power stroke. As the piston approaches the top of its compression stroke, the air is hot enough from being squeezed down so small that when diesel fuel is injected, it immediately ignites. Thus, the timing of ignition for diesel engines is driven by the fuel injectors. Both engine types function similarly for the exhaust stroke, where a valve opens up and the piston forces the spent fumes out of the cylinder.
Efficiency Differences
While diesel engines continue to build a reputation of struggling with emissions, they actually have highly impressive fuel economy numbers in comparison to their gasoline counterparts. Indeed, diesel engines are significantly more efficient in most cases, especially when the throttle pedal is only partially depressed. Much of this is due to differences in the strokes described above, in combination with the self-ignition temperature. The self-ignition temperature is the temperature at which an air-fuel ratio will combust simply from heat alone. In gasoline engines, it is critically important that the self-ignition temperature is never reached during the compression stroke, as this would cause combustion to occur before the spark plug fires, potentially destroying the engine. As a result, gasoline engines have relatively low compression ratios (the amount the air and fuel is squeezed down during the compression stroke), because compression causes a rise in temperature. As diesel engines do not have fuel in the mixture during the intake stroke, they can compress the air much more, exceeding the diesel fuel’s self-ignition temperature. Higher compression ratios equate to higher efficiency, so diesel engines take advantage of this by injecting fuel into the air after it is compressed.
Another diesel efficiency benefit comes from the lack of a throttle body. When you press the accelerator pedal a gasoline vehicle, this opens a valve in your engine’s intake, allowing more air to enter the engine, and thus create more power. The engine’s computer realizes it needs to inject more fuel for the additional air, but you can think of the accelerator pedal as an “air pedal” in this case. For diesel engines, a throttle valve is not necessary. In this case, the accelerator pedal regulates how much fuel is injected. The throttle body used in gasoline engines acts as a restriction, especially when the throttle is only partially open, and this is part of the reason why diesel vehicles have better fuel economy in low load scenarios.
Air/Fuel Ratio Differences
What allows diesel engines to operate based on how much fuel is injected? One reason is the ability of diesels to operate within a very wide range of air/fuel ratios. Gasoline engines generally operate within a range of about 12 to 18 parts air to 1 part fuel (by mass). Usually, this ratio stays pretty close to 14.7:1, as at this ratio all of the fuel and oxygen is completely used up. A diesel engine, however, generally operates from 18:1 to as high as 70:1, and is capable of operating in super lean ratios. When you press the accelerator pedal in a diesel engine, this drops the air/fuel ratio. Significantly more fuel is injected relative to the air ingested, which increases horsepower. Soot is created when diesel engines operate in low air/fuel ratios, which is why you may see black smoke from diesel trucks when they floor the throttle pedal. Ultimately, while the four major strokes are the same for both diesel and gasoline engines, the finer details reveal the highly unique characteristics of each engine type.
Along with the differences outlined above, there are also major distinctions in how each fuel type is capable of slowing down a vehicle, known as engine braking. For more information, check out the video below.
Jason Fenske is the brains behind Engineering Explained and is here to make sure you know how your car works. Subscribe to his YouTube channel.
Class A Gas Motorhome versus Class A Diesel MotorhomePublished: Thursday, July 26, 2007Considered in the past as the exclusive pastime of the rich and elite, holidaying in recreational vehicles, has today become the favorite recreation of almost all classes of the American society. As with improvement in the nation’s overall economic conditions, a larger section of the population is enjoying disposable income on hand, people from diverse age groups are today resorting to travel by recreational vehicles as modes of enjoying quality family time and relaxing holidays. In order to cater to the specific requirements and special preferences of different people, most manufacturers of recreational vehicles today are designing vehicles in a wide range of structures, internal designs and equipped with a variety of comfort facilities. Available primarily as towable and motorized entities, the recreational vehicle industry today enjoys a market of $15.75 billion per year. Depending on your budget, space requirements and lifestyle preferences, you can select from the various travel trailers, fifth wheels, Motorhomes, truck campers and park models available today. Among the rest, Class A Motorhomes are some of the best recreational vehicles you can opt for in modern times. Spacious, luxurious and provided with all comfort facilities of home, Class A Motorhomes provide you home away from home with all comforts you have ever dreamt of. Powered either by diesel or gas, Class A Motorhomes are, no doubt, expensive units to maintain, but once you experience traveling in them, holiday trips will acquire a whole new meaning for you.For large families and people preferring to enjoy their holiday trips with large groups of families and friends, diesel pushers form the best options. While the best quality diesel powered Motorhomes available in the present day recreational vehicle market are priced far higher than their gas powered counterparts, these diesel pushers are also some of the most spacious and luxurious travel vehicles available today. As a diesel powered Class A Motorhome is more fuel efficient than a gas engine, in the long run, you get to save more in running the vehicle. Whereas, the engine of a diesel pusher is situated at the rear of the vehicle, the fuel tank of these vehicles also has larger capacities. Another main advantage of diesel powered Motorhomes is that because of their strength and power, you can conveniently tow along a boat or car while going on RV trips. Once you reach the destination site, you can simply detach the towed entity and use it independently for exploring the new locale. If you are planning to holiday in steep mountainous regions, diesel pushers can prove more convenient as they are better geared to travel uphill with lesser engine strain. Whereas, brand new diesel pushers are some of the most expensive vehicles present in the recreational vehicle market, today, you can also get second hand diesel powered vehicles that are available at prices comparable to that of gas powered Motorhomes. While diesel Motorhomes are more expensive to maintain, life span of these vehicles is also usually longer. In comparison to gas powered Motorhomes, however, diesel pushers generate more noise and are slower in movement. However, diesel pushers are quiet in their cockpit areas and because of air suspension offer smooth rides. Spacious, comfortable and equipped to provide you all comforts of home, gas powered Motorhomes are more affordable than diesel pushers as far as initial investments are concerned. With a starting price usually around $70,000, you can select gas powered Class A Motorhomes complete with comfortable living, dining, sleeping areas, kitchens and private baths. For small families looking forward to relaxing weekend getaways and short trips, conventional gasoline powered Motorhomes form both affordable and luxurious options. When properly maintained, a gas chassis can efficiently serve for at least 150,000 miles if not more. Although for diesel pushers, this mileage is better, the fact that the cost of oil and filter change and other labor rates are far higher for diesel driven vehicles, make gas powered Class A Motorhomes a more affordable option. Diesel pushers are equipped with air brakes and air rides, but as these entities require regular, expensive servicing, gas Motorhomes prove more economic to maintain in the long run. While both diesel and gas driven Motorhomes have their own set of advantages and disadvantages, there are certain factors you should always keep in mind while purchasing either. Quality always comes at a premium. Make sure all parts of the motorhome you are selecting, both in its external structure and internal infrastructure, are in best working conditions at the time of purchase. The price of new recreational vehicles depreciate quickly; so before investing in one it is wise to calculate how much you stand to gain out of the deal. Class A Motorhomes come in a variety of lengths and sizes. As many camping grounds have facilities to accommodate vehicles up to specific dimensions only, make sure to select a model that will be allowed entry at most places you visit. Deciding on a budget from beforehand goes a long way in making wise RV selection. While purchasing a Motorhome, you can compare the facilities provided by diesel and gas driven models available within the same price range. As the basic advantages of a diesel pusher can be best experienced only after covering a lot of mileage, it is better to keep in mind the type of leisure travel plans you have while selecting a Motorhome. From the general perspective it can be said that while for a family traveling less than 6000 miles every year, a gas driven Motorhome forms a better option, for those intending to indulge in extensive cross country travels all through the year, diesel pushers may prove more profitable. Starting and smoothly operating the vehicles in cold climatic conditions and hilly roadways are other factors that significantly differ in gas and diesel driven engines. Unlike gas powered Motorhomes, as diesel driven engines are more susceptible to bacterial growth, regular addition of fungicides in the fuel tank, especially at hot humid times, is absolutely essential for the upkeep of diesel powered Motorhomes.
The RV, the perfect way to live life on the open road.
There’s such a romantic appeal to the thought of being able to take the creature comforts of home anywhere in the world. Be it a cross-country family vacation or you just have an itch to spend your life traveling instead of staying in one place, the RV is perfect for both.
In a world full of options and variety, the perspective wanderer has two options, the gas RV or the diesel RV.
If you’re left scratching your head and don’t have any clue where to begin your search, look no further. We are going to break down the gas RV vs. the diesel RV and hopefully help make your decision a little easier.
1. Price
We are going to start with the price first because it’s often the factor most consider before anything else.
Before you even begin comparing the two, I highly recommend establishing your ideal budget, so you have an idea of where to start.
For the sake of argument, let’s say you’re looking to buy a new RV.
The average price of a brand-new gas RV has an MSRP of approximately $80,000 to $150,000 depending on the options you want to include.
A new diesel RV is considerably more expensive with an average MSRP of $170,000 to $200,000.
Personally, I feel like a diesel RV is a better a better long-term investment because they have higher resale value should you decide to upgrade in the future.
To summarize, the gas RV is the best option if you’re on a budget but the diesel RV cost more but will yield a higher return should you put it on the market in the future.
2. Fuel Economy
Before we go any further let’s acknowledge the fact that fuel is expensive, fuel prices alone can be a huge factor in your decision so let’s look at the average mile per gallon for both engines and a few other fuel economy factors to consider.
3. Upkeep and Mechanical Considerations
Maintenance and the mechanics of the vehicles are where we begin to notice the fundamental differences between the two engine types.
One engine is faster while the other can pull anything up a hill.
Servicing of the two engines couldn’t be more different, one requiring specialized training while the other requires a general knowledge of basic engine repair.
Pay attention because these categories are significant in deciding between the two RVs.
Servicing
Historically speaking, gas engines are much easier to maintain and repair compared to a diesel engine. If you have a general knowledge of gas engines, you can probably do a bulk of the repairs and maintenance yourself, plus gas engine parts are much easier to find than their counterparts.
The downside of a gas engine is they run at higher RPMs, meaning the engine will always be working harder than a diesel engine, so more frequent upkeep is required to keep your gas RV running at optimum condition.
Diesel RV engines are much more expensive to maintain compared to gas RV engines. If you’ve ever seen a diesel engine, you know they are very complicated and require specialized training to service.
However, diesel engines run at a lower RPM, there is less strain on the engine so you can put in more miles between servicing.
OilMotorhome Class A Gas Vs Diesel Pusher
Both RV engines require oil, gas engines use about three times less oil than diesel engines, but you’ll need to change the oil in a gas engine every six months, diesel engines consume more oil but only need to be replaced once a year or every 15,000 miles.
In a gas engine, if you know how to change oil, you can do it yourself, diesel oil changes are more complicated, so you’ll probably have to take it to a professional mechanic to make sure the oil changes are correct.
Brake Systems
The braking systems of the two RVs can differ substantially as well.
Most diesel RVs have air brakes due to the increased torque, so if you’re uncomfortable with actuated braking systems when, say, driving on a steep downgrade, you’ll probably be more comfortable with the standard braking operation of a gas RV.
Torque and Horsepower
Here’s where it gets a little tricky.
Gas engines typically have higher horsepower and less torque, so you can accelerate and maintain higher speeds but having less torque adds more strain on the engine while towing and climbing inclines.
Diesel engines are designed for higher torque at lower speeds but offer lower horsepower than gas engines.
Increased torque means slower acceleration speeds but greater towing power and ease of coaching the vehicle up steep inclines.
Let’s Sum Everything Up
As you can see, both diesel and gas RVs are very similar yet remarkably different.
There are some pros and cons to both, but ultimately, the decision boils down to personal preference and budgetary concerns.
Not to sound biased but I would choose diesel for its fuel economy, higher torque and historically higher resale values opposed to gas RVs.
What is your preferred RV? We would love to hear your thoughts on gas and diesel RVs so please feel free to comment and tell us your best RV stories.
Thank you for taking the time to read our break down of the two, and I hope you’ve gained some insight. Safe travels my friends.
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What's the difference between a diesel engine and a gas engine? Is one better than the other? Depending on what you need it for, and your personal preferences, in some instances a diesel engine may be a better option than gas. For instance, fuel economy is a big consideration for many people when considering which vehicle is a good fit for them.
To make that decision, it's useful to understand the differences between the two types of engines.
Gas Versus Diesel Engines
In a modern gasoline engine gas, or fuel, is delivered to each cylinder of the engine by a fuel injector. The injector sprays a fine mist of fuel into each cylinder just above the intake valve. This mixes with air that comes in through the air filter and related air intakes, then flows through the intake valve of each cylinder.
In a diesel engine, the fuel is injected directly into the cylinder. mixing with the air there. The diesel injector is within the combustion area of the engine, so diesel fuel needs to be 'tougher' than gasoline.
Fuel Economy and Diesel Engines
Diesel engines get better fuel economy simply because they do not need to burn as much fuel as a gas engine to get the same power. Diesel engines are also built heavier than a gas engine to sustain the added stress of the higher compression ratio. Diesel engines do not have an ignition system so you will never have to give them tune-ups. Exhaust systems last longer because diesel fuel exhaust is not as corrosive a gasoline engine exhaust.
Diesel Engines and NoiseClass A Diesel Vs Gas Motorhomes
One big downside of diesel engines: They are very noisy. You will get the typical diesel clatter at idle, but that goes away off idle. At normal driving speeds, they are as quiet as a gasoline engine. You won't get the same acceleration that you get from a gasoline engine, but a turbo diesel will get up and go fairly quickly. You will need to adjust your driving habits somewhat also.
Maintenance of Diesel Engines
With gas engines but especially with diesel engines, regular oil changes are a must. Diesel fuel is not as refined as gasoline and the oil will get dirtier than a gasoline engine. Replace air and fuel filters once a year. If you live in a cold climate, you will need to switch to a winter blend fuel to prevent fuel gelling. There are additives you can put in the fuel to help prevent this as well.
Keeping Diesel Engines Warm
Replace glow plugs (the heating devices used to warm diesel engines so they start) every two years as well. If temperatures drop below 10 degrees Fahrenheit, it's probably not a bad idea to use a block heater. This will ensure that your diesel engine starts easily in cold weather, especially with the heavier grade oil that diesel engines require. Just be sure you know what you're doing; ask a mechanic for assistance if you want to install a block heater.
Should I Buy Diesel Or Gas TruckEngine Operation Differences
For gasoline engines, the intake stroke generally involves pulling air and fuel into the combustion chamber. At this point, a diesel engine is only pulling in air. Next is compression, where both engine types squeeze down the air into a small pocket. Ignition is controlled separately for each fuel type. Gasoline engines use a spark plug to time and start the power stroke. This small arc of electricity ignites the air fuel mixture and the powerful blast forces the piston down, churning out that highly craved horsepower. A diesel engine, on the other hand, only has a pocket full of hot air before the power stroke. As the piston approaches the top of its compression stroke, the air is hot enough from being squeezed down so small that when diesel fuel is injected, it immediately ignites. Thus, the timing of ignition for diesel engines is driven by the fuel injectors. Both engine types function similarly for the exhaust stroke, where a valve opens up and the piston forces the spent fumes out of the cylinder.
Efficiency Differences
While diesel engines continue to build a reputation of struggling with emissions, they actually have highly impressive fuel economy numbers in comparison to their gasoline counterparts. Indeed, diesel engines are significantly more efficient in most cases, especially when the throttle pedal is only partially depressed. Much of this is due to differences in the strokes described above, in combination with the self-ignition temperature. The self-ignition temperature is the temperature at which an air-fuel ratio will combust simply from heat alone. In gasoline engines, it is critically important that the self-ignition temperature is never reached during the compression stroke, as this would cause combustion to occur before the spark plug fires, potentially destroying the engine. As a result, gasoline engines have relatively low compression ratios (the amount the air and fuel is squeezed down during the compression stroke), because compression causes a rise in temperature. As diesel engines do not have fuel in the mixture during the intake stroke, they can compress the air much more, exceeding the diesel fuel’s self-ignition temperature. Higher compression ratios equate to higher efficiency, so diesel engines take advantage of this by injecting fuel into the air after it is compressed.
Another diesel efficiency benefit comes from the lack of a throttle body. When you press the accelerator pedal a gasoline vehicle, this opens a valve in your engine’s intake, allowing more air to enter the engine, and thus create more power. The engine’s computer realizes it needs to inject more fuel for the additional air, but you can think of the accelerator pedal as an “air pedal” in this case. For diesel engines, a throttle valve is not necessary. In this case, the accelerator pedal regulates how much fuel is injected. The throttle body used in gasoline engines acts as a restriction, especially when the throttle is only partially open, and this is part of the reason why diesel vehicles have better fuel economy in low load scenarios.
Air/Fuel Ratio Differences
What allows diesel engines to operate based on how much fuel is injected? One reason is the ability of diesels to operate within a very wide range of air/fuel ratios. Gasoline engines generally operate within a range of about 12 to 18 parts air to 1 part fuel (by mass). Usually, this ratio stays pretty close to 14.7:1, as at this ratio all of the fuel and oxygen is completely used up. A diesel engine, however, generally operates from 18:1 to as high as 70:1, and is capable of operating in super lean ratios. When you press the accelerator pedal in a diesel engine, this drops the air/fuel ratio. Significantly more fuel is injected relative to the air ingested, which increases horsepower. Soot is created when diesel engines operate in low air/fuel ratios, which is why you may see black smoke from diesel trucks when they floor the throttle pedal. Ultimately, while the four major strokes are the same for both diesel and gasoline engines, the finer details reveal the highly unique characteristics of each engine type.
Along with the differences outlined above, there are also major distinctions in how each fuel type is capable of slowing down a vehicle, known as engine braking. For more information, check out the video below.
Jason Fenske is the brains behind Engineering Explained and is here to make sure you know how your car works. Subscribe to his YouTube channel.
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