Heavy vehicles like trucks and trains need higher temperature and power for a quick ignition spark. In such types of vehicles, slow-combusting diesel has proven to be the most efficient fuel that can burn even at moderate temperature. No matter the size of the diesel engine, you can expect it to provide the greatest efficiency.
Trucks and other bulky vehicles need a significant amount of force to run even at the slowest speed. Keep in mind that petrol burns faster than diesel.
So, diesel engines can achieve a higher torque even at lower speeds. This is simply an essential requirement in any heavy automobile. Since petrol engines generate lower RPM, they result in quick fuel burning. Needless to say, petrol engines for heavy vehicles are simply not a practical option. On the other hand, diesel engines for trucks provide better fuel economy. This means that a gasoline engine makes it's torque at much higher RPM than a diesel.
This high end torque characteristic makes a gasoline engine hard to drive necessitating constantly keeping the RPM high. The only real draw back to this torque production is a limited RPM. This is compensated by a gear box with lots and lots of gears. If a gasoline engine was used it would have to be much larger. The much larger engine would make for greater fuel consumption. A major, but often overlooked, reason for the dominance of gasoline engines in passenger vehicles is the need for diesel engines in heavy vehicles.
A given quantity of crude oil, depending on its composition, will yield a given quantity of diesel, a given quantity of gasoline, a given quantity of candle wax, and specific given quantities of other petroleum products. Therefore, if we fix the amount of any one of these products that we need as constant, then we've also fixed all the other products' quantities as constant as well.
The heavy vehicles get the diesel-powered torque-producing motors. Let us fix the amount of diesel fuel needed to move a given nation's goods via diesel. Now, we've got a fixed quantity of gasoline that was produced as a byproduct of producing that diesel fuel. It makes much more sense to put gasoline engines in the passenger vehicles which can burn this leftover gasoline, than to put diesel engines in the passenger vehicles which will then compete for the fixed quantity of diesel being produced.
Thus, neither engine type would be economically well suited for use in all vehicles, regardless of technical considerations. Whenever fuel for one engine type is created, fuel for the other engine type is created as a byproduct and someone will come along with an engine that can burn that byproduct.
Diesel engines are significantly more expensive, but have lifetimes many times greater than gasoline engines. For a commercial vehicle that is on the road all day every day, it adds up to big savings because of the better fuel efficiency and less downtime for repairs.
Car companies claim that even if diesel powered consumer vehicles are superior to gasoline, consumers in the US won't buy them. It's not worth debating the validity of that claim here, but it is worth noting that in other places such as Europe, a large percentage of consumer vehicles are diesel. So the answer may be more cultural than scientific whether I mean US consumer culture or Big Three car company culture is open for interpretation.
Given two engines of similar weight, both operated at their respective optimum efficiency i. But a Diesel engine will generally offer slightly more power out of this, by giving more torque; that's how it's more efficient. However, such optimum efficiency is always reached at pretty low RPM. Now, piston engines actually offer most power at high RPM, albeit at the cost of reduced efficiency.
For trucks, this isn't economic though. Another consideration, in the United Kingdom at least, is that you can buy "red diesel" diesel fuel, dyed red for use in agricultural use, stationary generators etcetera with far less tax.
If a similar thing occurs in other countries this is no doubt one reason that diesel engines dominate these industries. You would not be able to make a petrol engine that would use sufficiently less fuel over its lifetime to recoup such a fuel cost differential. I don't know but I would venture to suggest that such a situation arose years ago when petrol engines simply couldn't produce the required torque or reliability at the required conditions so diesel was the preferred option.
Legislation on fuel tax for different uses will not keep up with modern rates of development by private companies. Granted, the red diesel argument doesn't cut it with road going vehicles, but when you consider the load pulled in a 40' trailer is comparable to that of a tractor and trailer in a field it is easier for engine manufacturers to make two similar engines tailored to the market.
I don't know anywhere near enough about who owns who when it comes to diesel engine manufacturers over the past fifty years but it is at least some food for doubt. Finally, if everyone used diesel, the police would have to check every vehicle for red diesel in the fuel tank, rather than the small percentage that could feasibly use it today. Biodiesel is made from non-petroleum sources such as fry oil or vegetable oil.
Indeed, the first diesel engines ran on peanut oil-derived diesel fuel. And while making your own gasoline at home is very complex, dangerous, and ill-advised, it is possible to safely make your own biodiesel using ready-made kits.
There is a large biodiesel community online that can answer questions about the popular alt-fuel. The per-gallon cost of bio-diesel may also be higher than pump fuel, but since you can make it yourself, it really depends on aggregating the cost of the equipment, the oil source which can be free , and your time. The output of gasoline and diesel engines is measured in terms of horsepower and torque.
Big amounts of both are great, but if you have a lot of horsepower with only a little torque, your vehicle is going to be slow to get going. What car manufacturers have found is that drivers love torque, both in pickups and cars. Step on the accelerator pedal and a diesel-powered car has brisk acceleration. Coupled with a capable transmission, modern diesel engines can get going fast in a hurry. And because they come from a workhorse heritage, they tend to be reliable and require relatively little care.
Also, a diesel engine is simpler than a gas engine since it runs without spark plugs and the associated electrical system needed for them. Now, cars and SUVs can run on diesel and have performance more akin to a gas engine, but with the added gas mileage and reliability of a diesel.
In general, a diesel engine will outlast a gas engine in terms of how many miles or hours it can run before it needs major service, so repair bills are smaller and typically further apart for a diesel engine. This is one reason diesels have traditionally had a hard time making inroads in the new car market — especially in the wake of Dieselgate — but technology has caught up and now diesels run cleaner than ever before.
This applies to big rigs, pickups, and cars, though, diesels can still be dirtier than cars because the fuel does not burn as cleanly as gasoline. Look for this link on your favorites: Save. Diesel vs. Gas Trucks: Pros and Cons. Torque and Towing : Diesel trucks are popular as work trucks and transport vehicles for their incredible torque, which often translates into sky-high towing capacity figures as well. Most diesel engines last longer than your typical gas-powered truck.
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