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Old 09-08-2008, 06:11 PM   #1
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Boxer diesel, you bet.

September 5, 2008 We’d been looking at pictures and static displays of Subarusubaru ’s horizontally-opposed diesel enginediesel engine for several years before seeing it in the Legacy and Outback earlier this year. The engine is exceptionally compact, very light and has a low centre-of-gravity which benefits handling agility and makes best use of the all-wheel drive system. Throw in gobs of torquetorque (the 2.0 litre version produces 258 lb ft at 1,800 rpm), class-leading fuel economy and emissions and the refinement, smoothness and sharp throttle-response it has already displayed and it makes the coming Forester Boxer Diesel which goes on sale in later this month and the Impreza Boxer Diesel (January 2009) very enticing indeed. The Forester will be unveiled in Paris next week.

Both the new Forester SUVsuv and Impreza five-door will be unveiled next week at the 2008 Paris Motor Show featuring Subaru’s highly-acclaimed new 2.0 litre (150 PS at 3,600 rpm) Boxer Diesel engine.

Both the Forester and Impreza Boxer Diesels feature new six-speed manual gearboxes while the engine itself benefits from a new closed-type dieselhttp://en.wikipedia.org/wiki/Diesel particulate filter.

No other SUV can better the 44.8 mpg Combined and 167 g/km of the Forester 2.0D X.

The Forester 2.0D produces 147 PS and 258 lb ft torque and the Impreza 150 PS and 258 lb ft – both at 3,600 rpm and 1,800 rpm respectively.

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Old 09-08-2008, 06:42 PM   #2
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And we're never going to see one in the US?
(At least for another few years)
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Old 09-09-2008, 09:28 AM   #3
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And we're never going to see one in the US?
(At least for another few years)
You're probably right, but subaru is crazy not to. With that kind of mpg rating I'd think they would fly off the dealership lots.
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Old 09-09-2008, 09:41 AM   #4
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I continue to wave the diesel flag and hope that this country begins accepting what the Europeans have understood for a while now.

I would much rather have a 62MPG diesel Golf than a 50MPG Hybrid Prius.

http://blogs.thecarconnection.com/blogs/marty_blog/2009/vw-golf-bluemotion-concept-gets-62-mpg/

Diesel is not a transitional technology. The engines are robust and produce loads of torque. Still, I wonder what would happen if someone built a diesel hybrid...
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Old 09-09-2008, 01:50 PM   #5
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I agree. Diesels cars are much better than any hybrid alternative, and can go more than an electric cars 120 miles range. GM and Ford have diesels in Europe but not in the US and know they are paying the price. (They just asked the US for a $15 billion loan.)
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Old 09-09-2008, 04:57 PM   #6
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Originally Posted by rick3000
I agree. Diesels cars are much better than any hybrid alternative, and can go more than an electric cars 120 miles range. GM and Ford have diesels in Europe but not in the US and know they are paying the price. (They just asked the US for a $15 billion loan.)
There are two reasons we are not getting the diesel cars.
1- our rediculous trucking industry consumes so much diesel that could be saved had we a realistic rail system, like europe and
2-the amount of gasoline and diesel from a barrel of oil is not adjustable. We get x number gallons of gas and x number gallons diesel from a barrel of oil and it is ALL already spoken for. More diesel cars would just run the demand, and price, up so high on diesel that it would more than offset the mpg savings.
I'm too tired to go looking for a link tonight, but the number of miles a train can take a ton of freight on a gallon of diesel will make you sick.
A new rail system would go a long, long way to solving our energy problems. Run trains hub to hub and deliver via truck from there. Set up the stations like a modern airport. There's no reason modern technologies and computer controlled inventory movement cannot make the load/unload slicker than owl dukey. Pay Walmart to run it. Their warehouse, load/unload systems are phenominal and a major reason they are able to sell at the prices they do.
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Old 09-09-2008, 05:04 PM   #7
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That's true. But if you get double (or more) the mgp, like going from 25 to 60, even if diesel goes up $2 to $6 a gallon, your still saving money. The price would have to double to make it not cost effective.
Plus, they can just use the same oil to make more diesel instead of more gas. (Correct me if I am wrong)
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Old 09-09-2008, 05:07 PM   #8
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Quote:
Originally Posted by rick3000
That's true. But if you get double (or more) the mgp, like going from 25 to 60, even if diesel goes up $2 to $6 a gallon, your still saving money. The price would have to double to make it not cost effective.
Plus, they can just use the same oil to make more diesel instead of more gas. (Correct me if I am wrong)
You wrote this while I was doing a bear paw edit, but no, the amount of diesel and gas from a barrel of oil is not very adjustable, if at all. I think maybe different grades of crude get different amounts of each, but my understanding from those who are supposed to know say it's not adjustable.
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Old 09-09-2008, 07:45 PM   #9
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@Quickurt:

You're right, the amount of diesel from a barrel of crude (42 gal.) is fixed at a little over 9 gal./bbl. And this is after it's refined. Raw, a barrel of crude only contains about 7 gal. of diesel grade fuel.

It's not the answer for personal transportation for this country in the long run, right now, fuel cells show the greatest promise. As you stated, it is a very efficient transporattion fuel when used to long-haul freight by rail. The figure you're looking for is one gallon of diesel can move one ton of freight 423 miles by rail vs about 130 miles by diesel truck. 1 freight train can remove the equivalent of 280 long-haul (500+ mi.) trucks from the road.

Another benefit to a rail transport system though is a reduction in GHGs. Moving a ton of freight by rail reduces greenhouse gasses by more then 2/3 that of the same ton moved by diesel truck. And that does not include extra GHGs produced by personal cars due to road conjestion caused by the volume of trucks on the road. Also an estimated $60B in wasted time and 2.3B gal. of wasted fuel would be saved. Not to mention reduced wear & tear to the infrastructure. Sources: AAR - Assn. of Am. Railroads, AASHTO - Am. Assn. of State Highway and Transporation Officials.
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Old 09-10-2008, 05:54 AM   #10
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Quote:
2-the amount of gasoline and diesel from a barrel of oil is not adjustable. We get x number gallons of gas and x number gallons diesel from a barrel of oil and it is ALL already spoken for.

That seems easy enough to solve - we all just need to do our part to use more gasoline, then there will be more diesel, and then we can get the cool Subie versions...simple yes/no?
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Old 09-10-2008, 07:01 AM   #11
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From Wiki

[edit] Advantages and disadvantages versus spark-ignition engines

[edit] Power and fuel economy


Diesel engines are more efficient than gasoline (petrol) engines of the same power, resulting in lower fuel consumption. A common margin is 40% more miles per gallon for an efficient turbodiesel. For example, the current model Skoda Octavia, using Volkswagen Group engines, has a combined Euro rating of 38 miles per US gallon (6.2 L/100 km) for the 102 bhp (76 kW) petrol engine and 54 mpg (4.4 L/100 km) for the 105 bhp (78 kW) diesel engine.

However, such a comparison doesn't take into account that diesel fuel is denser and contains about 15% more energy by volume. Although the calorific value of the fuel is slightly lower at 45.3 MJ/kg (megajoules per kilogram) than gasoline at 45.8 MJ/kg, liquid diesel fuel is significantly denser than liquid gasoline. This is important because volume of fuel, in addition to mass, is an important consideration in mobile applications. No vehicle has an unlimited volume available for fuel storage.

Adjusting the numbers to account for the energy density of diesel fuel, one finds the overall energy efficiency of the aforementioned paragraph is still about 20% greater for the diesel version, despite the weight penalty of the diesel engine.



While higher compression ratio is helpful in raising efficiency, diesel engines are much more efficient than gasoline (petrol) engines when at low power and at engine idle. Unlike the petrol engine, diesels lack a butterfly valve (throttle) in the inlet system, which closes at idle. This creates parasitic loss and destruction of availability on the incoming air, reducing the efficiency of petrol/gasoline engines at idle. In many applications, such as marine, agriculture, and railways, diesels are left idling unattended for many hours or sometimes days. These advantages are especially attractive in locomotives (see dieselisation).


Weight can be an issue, since diesel engines are typically heavier than gasoline engines of similar power output. This is essentially because the diesel must operate at lower engine speeds.[3] Diesel fuel is injected just before the power stroke. As a result of this, the fuel cannot burn completely until it has encountered the right amount of oxygen. This results in incomplete combustion because not all of the fuel molecules can collide with enough oxygen molecules to react. In the gasoline engine, air and fuel are mixed for the entire compression stroke, ensuring complete mixing even at higher engine speeds.

Diesel engines usually have longer stroke lengths to achieve the necessary compression ratios. As a result piston speeds are higher and more force must be transmitted through the connecting rods and crankshaft to change the momentum of the piston. This is another reason that a diesel engine must be stronger for the same power output.

Yet it is this same build quality that has allowed some enthusiasts to acquire significant power increases with turbocharged engines through fairly simple and inexpensive modifications. A gasoline engine of similar size cannot put out a comparable power increase without extensive alterations because the stock components would not be able to withstand the higher stresses placed upon them. Since a diesel engine is already built to withstand higher levels of stress, it makes an ideal candidate for performance tuning with little expense. However, it should be said that any modification that raises the amount of fuel and air put through a diesel engine will increase its operating temperature which will reduce its life and increase service requirements. These are issues with newer, lighter, high performance diesel engines which are not "overbuilt" to the degree of older engines and are being pushed to provide greater power in smaller engines.


The addition of a turbocharger or supercharger to the engine greatly assists in increasing fuel economy and power output, mitigating the fuel-air intake speed limit mentioned above for a given engine displacement. Boost pressures can be higher on diesels than gasoline engines, due to the latter's susceptibility to knock, and the higher compression ratio allows a diesel engine to be more efficient than a comparable spark ignition engine. Because the burned gases are expanded further in a diesel engine cylinder, the exhaust gas is cooler, meaning turbochargers require less cooling, and can be more reliable, than on spark-ignition engines.

The increased fuel economy of the diesel engine over the gasoline engine means that the diesel produces less carbon dioxide (CO2) per unit distance. Recently, advances in production and changes in the political climate have increased the availability and awareness of biodiesel, an alternative to petroleum-derived diesel fuel with a much lower net-sum emission of CO2, due to the absorption of CO2 by plants used to produce the fuel. Although concerns are now being raised as to the negative effect this is having on the world food supply, as the growing of crops specifically for biofuels takes up land that could be used for food crops and uses water that could be used by both humans and animals. The use of waste vegetable oil, sawmill waste from managed forests in Finland funded by Nokia venture capital, and the development of the production of vegetable oil from algae, demonstrate great promise in providing feed stocks for sustainable biodiesel, that are not in competition with food production.

The two main factors that held diesel engine back in private vehicles until quite recently were their low power outputs and high noise levels, characterised by knock or clatter, especially at low speeds and when cold. This noise is caused by "piston slap", the sudden ignition of the diesel fuel when injected into the combustion chamber slamming the cold-contracted piston into the cylinder wall. The tolerances between the piston and cylinder wall are greater at cold temperatures to allow expansion at higher temperatures. A combination of improved mechanical technology (such as multi-stage injectors which fire a short "pilot charges" of fuel into the cylinder to warm the combustion chamber before delivering the main fuel charge), higher injection pressures that have improved the atomisation of fuel into smaller droplets, and electronic control (which can adjust the timing and length of the injection process to optimise it for all speeds and temperatures), have mostly mitigated these problems in the latest generation of common-rail designs, while greatly improving engine efficiency.

Poor power and narrow torque bands have been addressed by the use of superchargers, turbochargers, (especially variable geometry turbochargers), intercoolers, and a large efficiency increase from about 35% for IDI to 45% for the latest engines in the last 15 years.
Even though diesel engines have a theoretical fuel efficiency of 75%, in practice it is less. Large diesel trucks, buses, and newer diesel cars can achieve efficiencies around 45% [4], however they could reach 55% efficiency in the near future [5].

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