Diesel engines are heavier so a 2500 cc diesel engine will be heavier than a 2500 cc petrol engine because stronger parts are needed for their operation, this extra weight will reduce their performance levels. The turbo diesel engine will gain a higher percentage of the increase in horsepower but will not automatically become faster than a similar sized gasoline engine with a turbocharger offering the same amount of boost. Complexity is reduced in a diesel engine as there is no ignition system but this is not a total advantage as they can be noisy and may require frequent maintenance intervals when compared to a petrol engine.
Diesel engines can pull or carry heavier loads for longer distances because they produce more torque. That would explain why most trucks, pickups and vehicles that transport large amounts of cargo or have a high towing capacity have diesel engines. A petrol engine is a faster engine than its diesel counterpart because they generally have more horsepower. So the 2500 cc petrol engine will cover the 1/4 mile in a faster time than a 2500 cc diesel engine and it will accelerate from a standstill to 60mph in a shorter time.
A diesel engine produces a smaller amount of carbon monoxide in its exhaust gases but petrol is still considered to be a cleaner fuel as there is black soot and aerosols in the diesel exhaust gases. A diesel engine can offer some of the performance of the gasoline engine with the aid of a turbocharger. The engine retains all the advantages including better fuel economy than even smaller sized petrol engines and gains a significant increase in speed.
Common rail technology has moved diesel engines closer to their gasoline counterparts not just in speed but in quietness and refinement but common rail is also used to improve the petrol engine. Although the diesel engine may seem like the better engine and it is if you want the vehicle for heavy duty work or commercial purposes, it is my opinion that the petrol engine is the better option if money is not an issue as this engine provides a better refined driving experience.
There are very good diesel engines in some luxury models but the petrol versions usually out perform them when it comes down to the petrol vs. diesel debate. Yes, but you would be better off with a turbo due to the natural low end torque of the diesel engine. The turbo would give more power at the higher rpm were the diesel is weaker. Supercharging it would make the low end very powerful but the top end weak, think severe turbo lag in reverse. http://www. howstuffworks. com/gasoline2. htm Gasoline is made from crude oil.
The crude oil pumped out of the ground is black liquid called petroleum. This liquid contains hydrocarbons, and the carbon atoms in crude oil link together in chains of different lengths. http://www. eia. gov/tools/faqs/faq. cfm? id=9&t=5 Why has diesel fuel been more expensive than gasoline? On-highway diesel fuel prices have been higher than regular gasoline prices almost continuously since September 2004, a break from the historical pattern of diesel fuel prices usually being lower than gasoline prices except in cold winters when demand for heating oil pushed diesel fuel prices higher.
The main reasons why diesel fuel prices have been higher than gasoline prices in recent years are: High worldwide demand for diesel fuel and other distillate fuel oils, especially in Europe, China, India, and the United States, and a tight global refining capacity available to meet demand during the period of high economic growth from 2002 to mid-2008. The transition to less polluting, lower-sulfur diesel fuels in the United States affected diesel fuel production and distribution costs.
The Federal excise tax for on-highway diesel fuel of 24. 4 cents/gallon is 6 cents per gallon higher the gasoline tax. http://www. wisegeek. com/why-is-diesel-fuel-more-expensive-than-gasoline. htm Diesel fuel, the kind of fuel commonly used in commercial trucks, has not always been more expensive than the standard gasoline used in passenger vehicles. On paper at least, diesel fuel is a less refined petroleum distillate than gasoline, so it should always be cheaper to produce than gasoline.
The problem with diesel fuel prices has more to do with the laws of supply and demand for various petroleum products, not the actual cost of production. A barrel of crude oil can be “cracked,” or broken down into a number of different products, from home heating oil to gasoline to kerosene. Oil refiners can only process a fixed number of these products at one time, however, so they tend to choose the products in highest demand at the time. This generally means gasoline for passenger vehicles takes precedence over diesel fuel for commercial vehicles.
When the supply of diesel fuel is low, the price naturally goes higher. At some point in the year, oil refiners concentrate their efforts on another product similar to diesel fuel: home heating oil. At this point, usually just before winter, diesel fuel becomes more plentiful and the price usually drops. This trend doesn’t always hold true, however, since a particularly cold winter can keep demand for home heating oil high and once again put diesel fuel production lower on the refiner’s agenda.
In recent years, the federal government has mandated changes to the acceptable sulfur level of diesel fuel, and refiners must comply with these mandates to create an ultra low sulfur diesel fuel product. This means significant investments in new technology and several distillations before the finished fuel is deemed acceptable by government inspectors. All of these additional regulations and high-tech equipment can cost billions of dollars, and these expenses are often passed onto consumers through higher prices.
There are also higher federal excise taxes placed on diesel fuel compared to standard gasoline. Some critics suggest the federal government is less eager to impose higher taxes on millions of private drivers than thousands of commercial drivers who use a less popular fuel. Part of the reason diesel fuel is more expensive than gas is the total amount of federal and state taxes added to each gallon. In many other countries, diesel fuel is still much cheaper than petrol, and there are significantly more diesel-powered passenger vehicles on European and Asian roadways.
If more drivers in the United States were willing or able to switch to diesel-powered vehicles, the price per gallon of diesel fuel might begin to fall below that of gasoline. More refineries would have the financial incentive to process more diesel fuel during peak driving months, and more fueling stations would offer standard diesel or the more ecological friendly bio-diesel at competitive prices. Volkswagen has long put faith in diesel technology as a way of offering both performance and economy to car buyers. In October, buyers will be granted a second option, however–with the launch of the 2013 Volkswagen Jetta Hybrid.
Using a 1. 4-liter, turbocharged and hybrid-assisted four-cylinder, the Jetta Hybrid will put out 170-horsepower, and uses a 7-speed dual-clutch DSG transmission. That’s enough to out-punch the already nippy Jetta TDI, a Volkswagen stalwart and a popular choice with those who want to save money on fuel. Rated at 30 mpg city, 42 highway and 34 combined–with the potential for more–it’s a quick and frugal sedan with well-proven technology. But will the Jetta Hybrid make it obsolete? Volkswagen estimates a 45 mpg combined rating from the EPA, which puts it 11 mpg ahead of its diesel stable mate.
It’s also likely to be significantly better than the diesel in city driving, with VW touting a 1. 2-mile electric range when it debuted at the 2012 Detroit Auto Show. Volkswagen even claimed, back at Detroit, that the Jetta Hybrid would be competitively priced with other compact hybrids. We expect that means it’s closer to the $24,000 Honda Civic Hybrid than the $20,000 Toyota Prius C, but anywhere in that range will make it an option for buyers looking at the $22,990 Jetta TDI. So where exactly does that leave the diesel Jetta?
Well, with less weight than the hybrid–3,161 lbs plays roughly 3,300 lbs–the TDI might still be the more nimble choice, and for many partisan Volkswagen buyers, diesel provides all the performance and economy they need–and let’s not forget, the EPA’s fuel efficiency ratings for the Jetta TDI are proving fairly conservative. When it comes to traversing great distances at highway speeds, the diesel engine’s higher compression ratios and lean-burn combustion provide an efficiency that no gas engine can currently match—at least not without a major assist from an expensive hybrid system.
Over the diesel’s operating range, the average thermodynamic efficiency—how much work the engine produces from the fuel—is in the mid 30 percent range, at least 15 percent better than a gas engine. Not even close, right? The reality is that this lead is shrinking. As emissions regulations stiffen, diesels are slowly losing their edge; the same pricey after-treatment systems that scrub diesel exhausts also happen to crimp efficiency. Meanwhile, gas engines continue to improve. There is certainly a convergence in efficiency levels between gasoline and diesel engines,” says Uwe Grebe, GM’s director of global advanced engineering. “While diesels will always maintain a slight advantage, the gap will nearly close in as little as 10 years. ” Over the past decade, once-exotic efficiency-enhancing hardware such as variable camshaft timing, direct fuel injection and turbochargers have become commonplace on spark-ignited engines. Certainly, these technologies aren’t new, but incremental improvements in electronics and materials have pulled them into the mainstream.
And there’s more on the way, like lean-burn combustion and homogeneous charge compression ignition (HCCI), a gas-combustion technology that blurs the line between gas and diesel engine cycles. Ricardo is working on a turbocharged engine that uses E85, a lofty compression ratio and high boost levels to achieve diesel-like efficiency. Rod Beazley, Ricardo’s VP of spark-ignited engines, boasts that“Ethanol-boosted concept engine achieves thermal efficiency in the low 40 percent range. ” But don’t expect the diesel engine to lie down and play dead. We’ll continue to see incremental improvements in diesel efficiency,” says Marc Trahan, Audi’s North American director of quality and technology. “It won’t be as large as going from sequential port fuel injection to direct injection, but there are still more gains to be made. ” Trahan says these smaller gains will come from hardware such as variable valve timing and independent cylinder combustion control, as well as improved after-treatment systems. Moreover, there are other factors in play.
As GM’s Grebe points out, diesel fuel contains about 14 percent more energy by volume than gasoline. This gives compression-ignition engines a significant edge in fuel economy, as opposed to thermal efficiency. Of course, everything will change if and when spark-ignited engines switch to more energy-dense fuels. This race is far from over. Read more: Gas vs. Diesel Engines in Fuel Economy – Gas or Diesel for Environment – Popular Mechanics http://www. answerbag. com/q_view/81096 Just ask VW, theyve done it to their golf on a 1. liter engine. I suspect the reason is one of fuel efficeincy without the lag of a turbo system. That is, turbo=more effient (generally) and supercharger= more responsive down low. Mix the two together and you get a responsive small literage motor with decent hp up top. They switch their supercharger off once above about 3500rpm to avoid excess fuel consumption… and by that pint, the turbo is making the required boost anyway. Read more: Can a car be turbocharged and supercharged at the same time?