Home Brew Electric Vehicle Conversions
The process of turning a gasoline power vehicle into a vehicle that
runs off of only electricity is called an electric vehicle conversion.
If you're not aware, there is a big movement going on across the country
in which people are doing "home brew" electric vehicles in order to
initially beat the ever-growing gas prices across the nation and to end
up ultimately end up making money by saving money in the end. After all,
it was Benjamin Franklin that said the famous quote, "A penny saved is a
penny earned." In the case of electric car conversions, this quote is
not only true, but it is also a life style.
Electric Vehicle Conversion Motors
In order to do your own electric vehicle conversion you have got to
be confident that you are knowledgeable in the field of electricity,
mechanics, and automobiles in general. If you're not, individuals can
always hire a mechanic in order to operate on your electric vehicle
conversion motors.
DC Electric Car Motors
If you are confident working on electric motors, then this article
is for you. Electric motors come in AC or DC versions. DC motors are
usually motors that have a wide range in voltage. Electric car
conversion motors can range anywhere between 96 and 192 volts. In fact,
almost all electric vehicle conversion motors come from the forklift
industry. Many lower power fork lifts are electrically powered motors in
order to do their lifting where as the heavy duty for lifts generally
use propane gas tanks which ride on the back of the fork lift.
AC Electric Car Motors
If the electric car conversion motor is of the AC variety it is most
likely three-phase running at 240 volts. Generally the 240-volt
electric vehicle conversion motor is accompanied by a 300-volt battery
pack. AC installations allow the individuals handling the electric car
conversion motors the use of almost any industrial motor. AC electric
car conversion motors are actually much easier to find in any size,
shape, or power rating.
Regardless of if you're the type of person
that prefers one of the electric car conversion motors over the other,
it should be known that if you are going to undertake the process of
doing an electric car conversion to your motor then you should be
thanked and praised for doing something that not only saves you money
but also saves the environment at the same time.
Selasa, 28 Februari 2012
Jumat, 24 Februari 2012
Fuel Efficient Cars Could Increase Your Carbon Footprint
It's always preferable for things to work in the most efficient
manner possible, especially if they run on harmful fossil fuels. This
logic has led many people, who wish to drive down the size of their
carbon footprint, to invest in a new, more fuel efficient car.
However, whilst there is no denying that owning a car which makes more use of the fuel you put into it will help you save money, especially in the light of astronomically high petrol prices, the question of whether your decision will actually benefit the environment is a lot less straight forward.
This is because you have to factor the emissions derived from the cars manufacture into the equation if you truly wish to base your decision on picking the greenest possible option. In some cases the truth of the matter is that, when the carbon footprint of manufacturing a new car is worked into the equation, you'd be better off finding a reasonably efficient second hand car. This is of course a recurring paradox for those who, as consumers, want to make greener choices- whilst fresh products are constantly being innovated and marketed as being 'eco-friendly', unless they are 100% recycled, it's normally more environmentally sound to buy something used, even if it is less 'green', than to buy anything new.
On top of this, when it comes to electric cars, it's important not to think of the vehicle as being zero emissions to run. Though they are called 'electric' cars, in reality they are, for the most part, powered by fossil fuels, as the plants that provided the power you use to charge the car will often run on substances such as coal.
Of course, it is much easier to make the case for such a switch if the car you currently drive is gas guzzling 4 x 4, or if, for example, you live somewhere where you can be sure that a decent amount of the electricity being supplied to the grid you'd use to charge the car comes from nuclear energy rather than fossil fuels, as would be the case in a country like France, for instance.
Whilst each case is different and has to be taken on its merits, it really is worth attempting to research the carbon footprint involved before buying a car, even if it is 'eco-friendly', and thinking about just how far you'd have to drive before the emissions you save by using it offset the emissions caused by its original manufacture.
However, whilst there is no denying that owning a car which makes more use of the fuel you put into it will help you save money, especially in the light of astronomically high petrol prices, the question of whether your decision will actually benefit the environment is a lot less straight forward.
This is because you have to factor the emissions derived from the cars manufacture into the equation if you truly wish to base your decision on picking the greenest possible option. In some cases the truth of the matter is that, when the carbon footprint of manufacturing a new car is worked into the equation, you'd be better off finding a reasonably efficient second hand car. This is of course a recurring paradox for those who, as consumers, want to make greener choices- whilst fresh products are constantly being innovated and marketed as being 'eco-friendly', unless they are 100% recycled, it's normally more environmentally sound to buy something used, even if it is less 'green', than to buy anything new.
On top of this, when it comes to electric cars, it's important not to think of the vehicle as being zero emissions to run. Though they are called 'electric' cars, in reality they are, for the most part, powered by fossil fuels, as the plants that provided the power you use to charge the car will often run on substances such as coal.
Of course, it is much easier to make the case for such a switch if the car you currently drive is gas guzzling 4 x 4, or if, for example, you live somewhere where you can be sure that a decent amount of the electricity being supplied to the grid you'd use to charge the car comes from nuclear energy rather than fossil fuels, as would be the case in a country like France, for instance.
Whilst each case is different and has to be taken on its merits, it really is worth attempting to research the carbon footprint involved before buying a car, even if it is 'eco-friendly', and thinking about just how far you'd have to drive before the emissions you save by using it offset the emissions caused by its original manufacture.
Rabu, 22 Februari 2012
Stagnation in Aerodynamics
The automotive industry has run into an invisible wall in
aerodynamics. In the last few years, most cars have aerodynamic
coefficients of around 0.3. This is a good value, however, it is hardly
pushing the boundaries of what is possible.
In 1989 the Opel Calibra was launched with a drag coefficient of 0.26.
Yes, the Calibra had some advantages in terms of the basic shape, it was a long, low coupe. But this is 2009, 20 years have passed since then. Yet, we have only a handful of cars that come anywhere near this value. One is the Toyota Prius with a Cd of 0.26 and the other is the Mercedes C Class Blue Efficiency with a Cd of 0.25. Meanwhile the 2009 Prius has been revealed and is claimed to have a Cd of 0.25.
So we are finally again at the point where we were 20 years ago. I find that very disappointing. I understand that there need to be some compromises for design, practicality and everyday usability, but I believe we can do better than this.
Lets take the VW Polo Blue Motion, for example.
This is basically the same car as the Polo 1.4 TDI, but it has some tweaks in gearing, aerodynamics and rolling resistance. They have fitted a grille with less ventilation holes in it and a roof spoiler to reduce the wake resistance of the car and a different front bumper. This, combined with narrower tires, takes the Cd down from 0.32 to 0.3. Now if it is this easy, why not produce every Polo like this? Instead of putting on the normal grille, put on this aerodynamic grille. How much does that cost you?
Meanwhile the Audi A2, which came out in 1999, had a Cd of 0.28 (the standard version).
Ten years down the line, the VW Polo comes in with 0.32. The 3L TDI version of the Audi A2 even had a Cd of 0.25, and the Blue Motion version of the VW Polo is 0.3, but 10 years later. Note that the Audi A2 had no such advantages like the Calibra in terms of basic shape. It is a small hatchback like the Polo. Are we making any progress here? I believe that we can get down to the range of ~0.2 in the near future. I think we could have been there already. What is holding us back is the priority of the styling and practicality over the aerodynamics of the car. The basic shape of the car is not penned by people who have a clear understanding of aerodynamics.
The Audi TT was an example of a car designed with no regard for aerodynamics. The sloping rear window design produced a lot of rear axle lift at high speed. There were high speed accidents and several people died. Then Audi acknowledged their mistake and fitted the TT with an ugly rear spoiler, some suspension changes and electronic stability control. Somebody should have said during the design stage, "That back window is the ideal angle of a wing, that is not gonna work on a car!"
Sometimes, the practicality aspect of it comes into play. When you have a sloping roofline, which is good for aerodynamics, that decreases the available rear headroom. Yet, in many cars, this compromise is perfectly acceptable for styling reasons.
Someday, somebody has to be bold and design a car with a Cd of 0.2. Of course, it has to have nice styling, and exceptional fuel economy. That is how you will get people to buy such a car.
Why is all this important? Because at highway speeds, wind resistance is the main force you need to overcome and it is directly proportional to the drag coefficient Cd. Changes in the drag coefficient translate almost directly to fuel consumption at highway speeds. In this climate of energy saving, instead of discussing how to power a car, should we not first reduce the amount of power that is required to move it around?
Someday the auto industry will again get moving with regards to aerodynamic innovation. I just hope that day comes sooner rather than later.
In 1989 the Opel Calibra was launched with a drag coefficient of 0.26.
Yes, the Calibra had some advantages in terms of the basic shape, it was a long, low coupe. But this is 2009, 20 years have passed since then. Yet, we have only a handful of cars that come anywhere near this value. One is the Toyota Prius with a Cd of 0.26 and the other is the Mercedes C Class Blue Efficiency with a Cd of 0.25. Meanwhile the 2009 Prius has been revealed and is claimed to have a Cd of 0.25.
So we are finally again at the point where we were 20 years ago. I find that very disappointing. I understand that there need to be some compromises for design, practicality and everyday usability, but I believe we can do better than this.
Lets take the VW Polo Blue Motion, for example.
This is basically the same car as the Polo 1.4 TDI, but it has some tweaks in gearing, aerodynamics and rolling resistance. They have fitted a grille with less ventilation holes in it and a roof spoiler to reduce the wake resistance of the car and a different front bumper. This, combined with narrower tires, takes the Cd down from 0.32 to 0.3. Now if it is this easy, why not produce every Polo like this? Instead of putting on the normal grille, put on this aerodynamic grille. How much does that cost you?
Meanwhile the Audi A2, which came out in 1999, had a Cd of 0.28 (the standard version).
Ten years down the line, the VW Polo comes in with 0.32. The 3L TDI version of the Audi A2 even had a Cd of 0.25, and the Blue Motion version of the VW Polo is 0.3, but 10 years later. Note that the Audi A2 had no such advantages like the Calibra in terms of basic shape. It is a small hatchback like the Polo. Are we making any progress here? I believe that we can get down to the range of ~0.2 in the near future. I think we could have been there already. What is holding us back is the priority of the styling and practicality over the aerodynamics of the car. The basic shape of the car is not penned by people who have a clear understanding of aerodynamics.
The Audi TT was an example of a car designed with no regard for aerodynamics. The sloping rear window design produced a lot of rear axle lift at high speed. There were high speed accidents and several people died. Then Audi acknowledged their mistake and fitted the TT with an ugly rear spoiler, some suspension changes and electronic stability control. Somebody should have said during the design stage, "That back window is the ideal angle of a wing, that is not gonna work on a car!"
Sometimes, the practicality aspect of it comes into play. When you have a sloping roofline, which is good for aerodynamics, that decreases the available rear headroom. Yet, in many cars, this compromise is perfectly acceptable for styling reasons.
Someday, somebody has to be bold and design a car with a Cd of 0.2. Of course, it has to have nice styling, and exceptional fuel economy. That is how you will get people to buy such a car.
Why is all this important? Because at highway speeds, wind resistance is the main force you need to overcome and it is directly proportional to the drag coefficient Cd. Changes in the drag coefficient translate almost directly to fuel consumption at highway speeds. In this climate of energy saving, instead of discussing how to power a car, should we not first reduce the amount of power that is required to move it around?
Someday the auto industry will again get moving with regards to aerodynamic innovation. I just hope that day comes sooner rather than later.
Senin, 20 Februari 2012
Volkswagen's Push for the Ultimate Eco Car
Volkswagen has been building concept after concept of the
ultimate eco car, based on technology that is very close to production.
Unlike some eco startup companies who are just hoping for miracles, VW
is looking to build what is today possible.
The first one in this series was the Volkswagen 1 Liter concept car, which appeared in 2002.
This was obviously pushing the envelope in terms of technical innovation but involved no miracles, if a fair bit of expensive technology. The body is made of carbon fiber and the chassis out of magnesium, so it is quite lightweight. It also has a dramatic swoopy shape and tandem rather than side by side seating for the driver and the passenger.
It cheats the wind using a narrower track at the back compared to the front, closed rear wheelwells, and flat wheel covers on the front wheels. The tandem seating, narrow overall width and the low total height help as well.
According to Volkswagen, it is powered by a single cylinder diesel engine of 300cc capacity, which delivers about 8.5 horsepower. This enables it to consume just under a litre per 100 kilometers.
Volkswagen showed another concept car in 2009, the L1.
This was pretty much the same concept as the car in 2002, a tandem two seater. Volkswagen updated the styling to actually make it look cool this time, something they did not bother doing with the original 1 liter car.
It is powered by a 800cc two cylinder turbodiesel, basically Volkswagen's bread and butter 1.6 TDI cut in half. It generates a maximum of 29 hp in this really relaxed eco tune. Volkswagen claims that the L1 consumes just 1.38 liters per 100 kilometers. While it is more than the 2002 car, one must note the differences: The 2002 1 Liter Car used a one off prototype diesel engine, this L1 uses a prototype engine, but one which is derived from a popular mainstream one. On those terms, the L1 is clearly the more realistic solution and clearly closer to production car status.
Note that I said closer, and not close.
What did get close was the next car, the Volkswagen XL1 unveiled in 2011.
VW's answer to the ultimate eco car has marched step by step from the ultimate engineer's prototype to something altogether more civilized and practical. Although the styling is reminiscent of the L1, the marked difference is of course the side by side seating. Suddenly it jumps from being an interesting technical exercise to possibly being in an actual Volkswagen showroom.
Volkswagen says the XL1 weighs just under 800 kilograms, so more than twice as much as the L1 Concept, which was 380kg. It is supposed to consume just about 1 liter per 100 kilometers, but this is no doubt more due to hybrid trickery as opposed to pure efficiency.
Let's think about a lower cost, production variant of this car:
There are 2 main compromises: Let's throw out the complicated hybrid system and just keep the turbodiesel engine, which should be sufficient with its 47hp. Let's get rid of the carbon fiber and replace all that with conventional steel. Now we end up with a heavier car, let's be pessimistic and guesstimate that it consumes double the fuel it does in its original form, so about 2 liters per 100km.
That is still a fantastic number compared to any car you can buy today, so let's really look at what other changes would have to be made to produce this car for real. The gullwing doors would have to go, but that is true of any concept car and perhaps the ride height would need to be raised slightly. Other than that, there are not many reasons why this car could not be produced. Unfortunately, it will not be produced.
Why? Because it makes no economic sense. As simple as that. In this era of the fashionable eco mindset and hybrid BMW X6's and VW Touraeg's this car makes no economic sense.
It is quite a stark indicator of where we are in terms of energy usage and fossil fuels. We have the technical solutions today, but they won't be produced, since economically it doesn't work.
However, this is not quite the end of the story. Part of the reason is that auto manufacturing has come to rely heavily on economies of scale, and such a car would not be able to share too much with other cars under the VW umbrella. It also has something to do with market acceptance of 2 seaters, which is not very good, to say the least.
So, I think Volkswagen's answer to the ultimate eco car will come very soon from the other direction, from a mainstream model, namely the VW Up!
The Up! Lite Concept from 2009 is a preview of what will arrive in the showrooms and sidesteps a lot of these issues. It is a 4 seater, it looks a lot more mainstream, and critically, shares its platfom completely with the standard Up!.
The Up! Lite Concept styling looks like a bridge between the XL1 and the mainstream models from Volkswagen. The question for me is where will the production model fit in that rather large gap?
At one cynical extreme, Volkswagen could take the standard Up!, slap some Bluemotion badges on it, put on some low rolling resistance tires, do lots of small aero tweaks with underfloor panels and wheel covers and plasticky bits and call it a day.
At the other extreme, they could actually produce this aero optimized body, so that it would be sharing just the platform and the interior but not the bodywork with the Up!. But this would be the much more expensive option.
Where do I think this will end up? Probably the first option. I don't think Volkswagen has forgotten the lessons learned with the 3L Lupo TDI.
While the 3L Lupo TDI was a technical success and delivered impressive fuel economy numbers, it was too expensive to be a financially viable product. Since then, VW has produced Bluemotion versions of almost everything it makes, and they are always carefully tweaked versions that have minimal additional costs and slightly better fuel economy. VW plays it safe with the Bluemotion models, and they do not stray too far off the standard donor car. That's why I don't think that we will see the Up! Lite Concept as it was shown go into production.
My best hope would be to see the Up! Lite inherit the front half of the standard Up! completely and to have a its own, optimized body shape from the B-pillar to the back of the car.
In terms of powertrains, it is pretty clear that the 0.8 liter TDI engine is coming, only question is when and how much power will it make, I would guess late 2012 to early 2013 and about 55 horsepower. Fuel consumption numbers are hard to guess but I think we should be looking at around 2.8 liters per 100 kilometers (for a straightforward diesel with no hybrid but just start-stop functionality).
It will actually be interesting to see which name the car carries when it comes to market, whether it will be branded as a Bluemotion following the other VW models predictably, or if it will be badged as an Up! Lite. I think that it will be "just a Bluemotion" if the changes from the Up! are minimal, and an Up! Lite if there is major differences between the two. In case we get the Up! Lite, I would also be curious to know which other Lite models Volkswagen will have up its sleeve in the coming years.
The first one in this series was the Volkswagen 1 Liter concept car, which appeared in 2002.
This was obviously pushing the envelope in terms of technical innovation but involved no miracles, if a fair bit of expensive technology. The body is made of carbon fiber and the chassis out of magnesium, so it is quite lightweight. It also has a dramatic swoopy shape and tandem rather than side by side seating for the driver and the passenger.
It cheats the wind using a narrower track at the back compared to the front, closed rear wheelwells, and flat wheel covers on the front wheels. The tandem seating, narrow overall width and the low total height help as well.
According to Volkswagen, it is powered by a single cylinder diesel engine of 300cc capacity, which delivers about 8.5 horsepower. This enables it to consume just under a litre per 100 kilometers.
Volkswagen showed another concept car in 2009, the L1.
This was pretty much the same concept as the car in 2002, a tandem two seater. Volkswagen updated the styling to actually make it look cool this time, something they did not bother doing with the original 1 liter car.
It is powered by a 800cc two cylinder turbodiesel, basically Volkswagen's bread and butter 1.6 TDI cut in half. It generates a maximum of 29 hp in this really relaxed eco tune. Volkswagen claims that the L1 consumes just 1.38 liters per 100 kilometers. While it is more than the 2002 car, one must note the differences: The 2002 1 Liter Car used a one off prototype diesel engine, this L1 uses a prototype engine, but one which is derived from a popular mainstream one. On those terms, the L1 is clearly the more realistic solution and clearly closer to production car status.
Note that I said closer, and not close.
What did get close was the next car, the Volkswagen XL1 unveiled in 2011.
VW's answer to the ultimate eco car has marched step by step from the ultimate engineer's prototype to something altogether more civilized and practical. Although the styling is reminiscent of the L1, the marked difference is of course the side by side seating. Suddenly it jumps from being an interesting technical exercise to possibly being in an actual Volkswagen showroom.
Volkswagen says the XL1 weighs just under 800 kilograms, so more than twice as much as the L1 Concept, which was 380kg. It is supposed to consume just about 1 liter per 100 kilometers, but this is no doubt more due to hybrid trickery as opposed to pure efficiency.
Let's think about a lower cost, production variant of this car:
There are 2 main compromises: Let's throw out the complicated hybrid system and just keep the turbodiesel engine, which should be sufficient with its 47hp. Let's get rid of the carbon fiber and replace all that with conventional steel. Now we end up with a heavier car, let's be pessimistic and guesstimate that it consumes double the fuel it does in its original form, so about 2 liters per 100km.
That is still a fantastic number compared to any car you can buy today, so let's really look at what other changes would have to be made to produce this car for real. The gullwing doors would have to go, but that is true of any concept car and perhaps the ride height would need to be raised slightly. Other than that, there are not many reasons why this car could not be produced. Unfortunately, it will not be produced.
Why? Because it makes no economic sense. As simple as that. In this era of the fashionable eco mindset and hybrid BMW X6's and VW Touraeg's this car makes no economic sense.
It is quite a stark indicator of where we are in terms of energy usage and fossil fuels. We have the technical solutions today, but they won't be produced, since economically it doesn't work.
However, this is not quite the end of the story. Part of the reason is that auto manufacturing has come to rely heavily on economies of scale, and such a car would not be able to share too much with other cars under the VW umbrella. It also has something to do with market acceptance of 2 seaters, which is not very good, to say the least.
So, I think Volkswagen's answer to the ultimate eco car will come very soon from the other direction, from a mainstream model, namely the VW Up!
The Up! Lite Concept from 2009 is a preview of what will arrive in the showrooms and sidesteps a lot of these issues. It is a 4 seater, it looks a lot more mainstream, and critically, shares its platfom completely with the standard Up!.
The Up! Lite Concept styling looks like a bridge between the XL1 and the mainstream models from Volkswagen. The question for me is where will the production model fit in that rather large gap?
At one cynical extreme, Volkswagen could take the standard Up!, slap some Bluemotion badges on it, put on some low rolling resistance tires, do lots of small aero tweaks with underfloor panels and wheel covers and plasticky bits and call it a day.
At the other extreme, they could actually produce this aero optimized body, so that it would be sharing just the platform and the interior but not the bodywork with the Up!. But this would be the much more expensive option.
Where do I think this will end up? Probably the first option. I don't think Volkswagen has forgotten the lessons learned with the 3L Lupo TDI.
While the 3L Lupo TDI was a technical success and delivered impressive fuel economy numbers, it was too expensive to be a financially viable product. Since then, VW has produced Bluemotion versions of almost everything it makes, and they are always carefully tweaked versions that have minimal additional costs and slightly better fuel economy. VW plays it safe with the Bluemotion models, and they do not stray too far off the standard donor car. That's why I don't think that we will see the Up! Lite Concept as it was shown go into production.
My best hope would be to see the Up! Lite inherit the front half of the standard Up! completely and to have a its own, optimized body shape from the B-pillar to the back of the car.
In terms of powertrains, it is pretty clear that the 0.8 liter TDI engine is coming, only question is when and how much power will it make, I would guess late 2012 to early 2013 and about 55 horsepower. Fuel consumption numbers are hard to guess but I think we should be looking at around 2.8 liters per 100 kilometers (for a straightforward diesel with no hybrid but just start-stop functionality).
It will actually be interesting to see which name the car carries when it comes to market, whether it will be branded as a Bluemotion following the other VW models predictably, or if it will be badged as an Up! Lite. I think that it will be "just a Bluemotion" if the changes from the Up! are minimal, and an Up! Lite if there is major differences between the two. In case we get the Up! Lite, I would also be curious to know which other Lite models Volkswagen will have up its sleeve in the coming years.
Kamis, 09 Februari 2012
Why Are Diesel Cars More Expensive Than Gasoline Ones?
Modern diesel engines rely on some advanced technologies, many of
which are more expensive than standard components for gasoline engines.
The most basic characteristic of diesels that allow them to be more efficient than gasoline engines is the compression ratio. While most gasoline engines have compression ratios in the range of 9:1 to 11:1, diesel engines can have 16:1 or even 20:1. The higher the compression ratio, the higher the efficiency, according to the laws of thermodynamics. Unfortunately, higher compression ratios also mean higher stress for the engine internals to cope with. Therefore all the parts of a diesel engine have to be made stronger to withstand those stresses over the lifetime of the engine. This of course means that a diesel engine will cost more in comparison to a gasoline engine.
The vast of majority of diesel engines for passenger cars are turbocharged, in order to produce competitive amounts of power. While a turbocharger gives diesel engines a great flat torque curve and strong power, it increases costs. The cost for the turbo itself is not the end of the story though. Since compressing the air using a turbocharger heats it up, it has to be cooled down again before being fed into the engine. This means the car needs an intercooler and the associated plumbing as well, again more costs.
Another key component of modern diesel engines is a high pressure injection system. These systems, more commonly known as "common rail" systems, pump the fuel up to very high pressures between 1000 and 2000 bars or even more. Because of this, a diesel car has to have a secondary fuel pump to achieve those high pressures, again more costs. Once the pressurized fuel is pumped into the common-rail, it is injected into the cylinders usually by using what is known as a piezo-injector. This is an injector that delivers very precise amounts of diesel using a piezo-crystal. The advantage of these injectors is the very flexible and precise delivery of fuel, which allows very good control over the combustion, allowing good economy and low emissions. The disadvantage is of course that they are expensive.
While high compression ratios are great for efficiency, combustion at high compression ratios also has some unwanted side effects. They tend to cause the formation of nitrogen oxides, or NOx. There are strict limits for NOx emissions in all legislative drive cycles, therefore the car manufacturers must reduce these emissions using exhaust after treatment systems. In comparison to a gasoline car, which usually would have just an ordinary three way catalyst for after treatment, a diesel car would (depending on the size) need in addition a catalyst to reduce NOx emissions. Another emission that diesel engines produce is particles, which also need to be handled by diesel particle filters.
All of these are additional costs that diesel engines have to put up with, and that is why they are more efficient but also more expensive than their gasoline counterparts.
The most basic characteristic of diesels that allow them to be more efficient than gasoline engines is the compression ratio. While most gasoline engines have compression ratios in the range of 9:1 to 11:1, diesel engines can have 16:1 or even 20:1. The higher the compression ratio, the higher the efficiency, according to the laws of thermodynamics. Unfortunately, higher compression ratios also mean higher stress for the engine internals to cope with. Therefore all the parts of a diesel engine have to be made stronger to withstand those stresses over the lifetime of the engine. This of course means that a diesel engine will cost more in comparison to a gasoline engine.
The vast of majority of diesel engines for passenger cars are turbocharged, in order to produce competitive amounts of power. While a turbocharger gives diesel engines a great flat torque curve and strong power, it increases costs. The cost for the turbo itself is not the end of the story though. Since compressing the air using a turbocharger heats it up, it has to be cooled down again before being fed into the engine. This means the car needs an intercooler and the associated plumbing as well, again more costs.
Another key component of modern diesel engines is a high pressure injection system. These systems, more commonly known as "common rail" systems, pump the fuel up to very high pressures between 1000 and 2000 bars or even more. Because of this, a diesel car has to have a secondary fuel pump to achieve those high pressures, again more costs. Once the pressurized fuel is pumped into the common-rail, it is injected into the cylinders usually by using what is known as a piezo-injector. This is an injector that delivers very precise amounts of diesel using a piezo-crystal. The advantage of these injectors is the very flexible and precise delivery of fuel, which allows very good control over the combustion, allowing good economy and low emissions. The disadvantage is of course that they are expensive.
While high compression ratios are great for efficiency, combustion at high compression ratios also has some unwanted side effects. They tend to cause the formation of nitrogen oxides, or NOx. There are strict limits for NOx emissions in all legislative drive cycles, therefore the car manufacturers must reduce these emissions using exhaust after treatment systems. In comparison to a gasoline car, which usually would have just an ordinary three way catalyst for after treatment, a diesel car would (depending on the size) need in addition a catalyst to reduce NOx emissions. Another emission that diesel engines produce is particles, which also need to be handled by diesel particle filters.
All of these are additional costs that diesel engines have to put up with, and that is why they are more efficient but also more expensive than their gasoline counterparts.
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