We have the freedom to drive what we like, you don't like it F you!!:mad: I do many track events a year and don't need some pansi poser like you telling me what to drive. Why don't you go back to europe since there are so many a$$ holes here, me included:mad:

Gadzooks.

Well, Jamie brings up what I would consider some pretty factual info.....Americans are oinkers & and the cars ~are~ huge....

It's this type of attitude that is really such a sad (and prevalent) thing in the US. So many people here think it's their God-given right to do whatever they feel like, waste as much fuel as they want, and basically not have to give a crap about anyone else, anywhere. It's really tragic, but what can you do with people that have this kind of attitude? They've been raised from birth to be selfish and not care; it's so hard to change that once it's set in. Maybe in future generations, but it's really hard right now...

ianc

What's really interesting about the attitude of " I'll drive what I want, and if you don't like it f### you" is that its applies mainly to those who complain the loudest when its done to them...

So you have the right to do what ever it is you like.... OK fair enough... what about when others want to exercise that right and its hinders you? Are you so supportive?

Say a politician would like to raise taxes to pay for a pet project? Or your neighbour would like ot play drums in th eopen air at 0200H?

No exercising your right to do as you please has to be tempered with the knowledge that others will do unto you as you do to others...

if you want to drive an SUV that does 10 mpg, fine.... but your choice will entain consequences on your wallet or other... However for driving to the shops or to work, as the primary task, the vehicle should be a 35mpg machine....especially if you are alone.

Choices should be free but the consequences should also be noticeable...at the moment there are none and whilst 'your' life is important 'our' life is also important.

You know, after some reflection, it occurs to me that your initial thesis was not entirely correct, in that consumers _are_ making a conscious effort to reduce gas consumption as prices rise. Perhaps sampling Porsche owners who (a) love driving more than life itself and (b) generally have the money to do what they need to do produces a less than accurate market population.

Even so, I made a conscious decision to reduce my driving this weekend. I carpooled, I walked, I used the foot-ferry -- all specifically because gas is more expensive. (shrug) Just a few thoughts...

Byron, its called social and ecological responsibility.

The European claims of environmental concern strike me as somewhat hypocritical. Over 40% of new cars sold there are diesel. The diesel NO2 emissions, WHICH HAVE NOTHING TO DO WITH THE QUALITY OF THE FUEL create wicked smog. These emissions are a basic byproduct of the diesel combustion cycle. Basically diesel combustion takes place at such high temps that atmospheric nitrogen gets oxidized and comes out as smog. AGAIN this has nothing to do with the ash content of the exhaust or the sulfur content of the fuel.

I spent some time in Barcelona last year and the smog was worse than anything I had seen since 1975 LA.

That said...yes, big American cars are also an endulgence in hypocrisy. I don't know how many people I know who have said:

"I drive an SUV because it is safer."

So let me get this....your SUV:

1. Can't accelerate as fast as most cars.
2. Can't brake in as short a distance as most cars.
3. And can't handle a turn like most cars.
4. And is more likely to flip over in an accident.

So how are those things going to make you safer? ...and it sucks gas...and it is tough to park.

Because, you know, in those instances when you hit someone smaller than yourself, you can crush them.

ianc

dj,

I hope you are right... however its relatively new thing... one could say a whole generation behind Europe, where the 1973 oil crisis spurred on the devlopment of much low SFC engines...and now we have 40mpg as a norm...

Diesel is a strange thing.. agreed the smog is a real problem and particulates even worse.. only a few with effective filters... however its appears that the technology is evolving more rapidly than petrol engines at the moment.. so there is potential to improve.

What is needed is to make sure the majority of users are thinking in the same direction.. which in the Us would tend to be disproven by the sales of the F150 and SUV type vehicles...

Talking about fuel economy on a Porsche site is however slight ironic... even if we try to use less on a daily basis to use more having fun...

I just had a discussion last week with one of my engineers on this topic, I told him to write a white paper on the "An Overview of the Combustion ProcessIn Modern Diesel Engines and The Relationship of Pollutant Generation". Here is what he penned this weekend. Let me know what you think. If it is legit and makes sense, I will have him publish it.

Poke holes in it. I would like your feedback.

Due to increasingly strict emissions standards in the United States, diesel engine manufacturers have developed interesting methods for the control of these emissions. This is particularly true for large diesel engine manufacturers. Several strategies have been implemented and will be reviewed here.

Diesel engines now occupy a place in our society that is so prevalent and so pervasive that these engines can not be displaced over the near or long-term future. As a result, 2 basic methods of pollutant reduction have been adopted. One of these methods is called Exhaust Gas Recirculation (EGR). This method uses a small amount of the engine exhaust to achieve pollutant reduction and will be explained later. The second method uses multiple injections of fuel into the combustion chamber. The biggest proponent of this method is Caterpillar (Cat) and this method will also be explained later.

In order to understand the solutions, a fast review of the dynamics of the diesel engine is necessary. Diesel engines achieve their power by the combustion of a fuel (diesel oil or diesel) that has a very high potential for the release of energy. The basic problem with the use of diesel is achieving the conditions necessary for the fuel to burn. In the 1880’s, Dr. Diesel realized that the easiest way to achieve the necessary temperatures to cause diesel to ignite was to compress air and achieve the temperatures necessary to cause ignition. If a quantity of air at ambient temperature is compressed to 4-5% of its original volume, the temperature of the air escalates enormously. 800°F is not uncommon. At this temperature, diesel will ignite and burn quickly; where at ambient temperatures, very poor combustion takes place. Here is where the downside of diesel engines starts to take place, at the combustion temperatures achieved in diesel engines sulfur mixes with the water that is a normal by-product of hydrocarbon combustion and creates sulfuric acid along with other sulfur oxides (SOx). In addition, the nitrogen that composes 70+% of ambient air is changed to nitric oxides (NOx) and nitric acid. Particulate Matter (PM) also became an interesting topic. PM is the black smoke often associated with diesels. The origin of PM is fuel that is not completely burned in the engine. What you are looking at is small specks of carbon that did not combine with oxygen to create carbon dioxide (CO2). While CO2 is invisible, unburned carbon is clearly visible.
The clatter normally associated with diesel engines is the result of very rapid combustion. Poor fuel will create a louder clatter because the fuel is burned at a very rapid, but incomplete, rate. The cetane rating is the measurement standard for this. If the start of the burn can be delayed slightly, the better the burn will be. If the burn rate can be controlled, then the noise drops and the more complete the combustion of the fuel.

Of the 2 problems, NOx and SOx, SOx was the easiest to cure/solve/reduce. A government mandate was issued and stated that the amount of sulfur in diesel fuel was going to be substantially reduced and it was up to the engine manufacturers to resolve the issue of creating engines that would work with “Low Sulfur Diesel.” At this point, it needs to be understood that the sulfur in diesel fuel not only behaved as a pollutant, but also as a lubricant for the bits of the engine that came into contact with the fuel. This means that the high pressure fuel pump that is absolutely necessary for engine operation was no longer going to receive the necessary lubrication to operate properly under the current fuel and design regime. New designs and/or different materials were going to be necessary to have pumps that were capable of operation for the amount of time mandated by customer expectations. Please remember that diesel engines have achieved expected lifetimes measured in hundreds of thousands of miles before ANY wear related parts replacements were to be considered. Any sort of lessening of this expectation was considered unacceptable. Cost was going to be a problem, but not one that could not be overcome.

Another problem associated with reduced sulfur fuel was going to be the cost of the fuel itself. Removing the sulfur to acceptable and mandated levels, was going to involve an increased cost in the production of the fuel. This cost would be passed along to the end user and passed on again to the end customer.

Alternate diesel fuels have come under consideration over the last few years, particularly the use of vegetable oils either straight or mixed with petroleum diesel. The vegetable oil-based diesels show promise because of their inherently high cetane and virtually no sulfur content but have some interesting problems to be overcome before wide acceptance occurs. Natural gas has also been tried to fuel diesel engines and the long term results of this are not available yet but there were some very interesting problems initially with reliability.

Removing NOx was going to be a greater problem. NOx is created when the pressures and temperatures in the combustion chamber achieve a certain point. Diesel engines were more than capable of creating these types of conditions; in fact, they needed them to work with any kind of efficiency at all. The manufacturers determined that there are 2 ways that a reduction in NOx could be achieved; one is to displace some of the oxygen in the combustion chamber and deprive the nitrogen of oxygen to bond with and the other is to lower the combustion chamber temperatures sufficiently to prevent the reaction form taking place at all.

Exhaust Gas Recirculation (EGR) is the simplest method for cutting down on NOx. EGR takes exhaust gas from the exhaust manifold, passes it through a heat exchanger to lower the temperature to whatever the engine temperature is, and then sends this gas into the combustion chamber. By using exhaust gas, the chamber air mixture is slightly reduced in oxygen content and the NOx reaction does not take place. Very little machinery is added to the engine to accommodate this idea. There is also very little weight added to the engine and this translates directly into no substantial reduction in fuel mileage. Most of the major manufacturers have adopted the EGR idea. Caterpillar went in another direction entirely and that will be explained later.

This method does have certain side-effects that directly affect the engine over the long run. One of these side-effects is the introduction of soot into the engine. Soot is the result of incomplete combustion. In theory, you mix hydrocarbons with air, get it to burn, and the end products are heat, water vapor, and carbon dioxide. Soot is elemental carbon. Soot is very abrasive. Soot is nothing more than sand that is made of carbon instead of silica. Introducing soot into the combustion chamber will mean that this soot will become mixed into the engine oil and be re-circulated through the entire engine. Wear on engine parts is increased substantially. The engine manufacturers have tried to combat this by increasing the volume of the oil in the engine. Another method is the increasing size of the filters that can trap the soot. Addition of filters that are designed for soot entrapment is a good method for the removal of soot. This means that more weight is added to the truck, decreasing fuel economy. Other items to think about are increased oil and filter costs for both initial purchase and disposal because much more oil is used and at least one more filter is required. Also note that nothing is done to reduce the PM. Catalytic converters have been considered but have been rejected because of the continued presence of NOx in quantities sufficient to damage the internal materials. The use of urea injectors is being tried in Europe but is not seen as a viable system for the United States. Another side-effect was a greater strain on the engine cooling system. The engine cooling system was used as the heat dump from the exhaust gas. Now larger radiators, more coolant, and a robust heat exchanger were going to be needed to reduce the exhaust gas temperature to something that would be acceptable the air intake side of the engine and not melt things in general.

Another reaction of the engine manufacturers was to create a new oil specification for EGR engines. This new specification, CI-4/SL, is designed to have a greater amount of dispersants in the oil to have the added soot remain floating about in the oil and not become attached to the metal parts on the hope that the soot will be trapped in the filters. It is safe to assume that the CI-4/SL oil has a higher cost than the previous oils. One thing to notice about this new specification is the reduction of the Total Base Number (TBN). With the reduction in the amount of sulfur in the fuel, the amount of sulfuric acid was reduced in the engine oil. This translated into a lower need for acid neutralization in the engine oil.

Caterpillar has taken a fairly unique approach to the NOx resolution problem. Caterpillar reasoned that if the combustion chamber temperature could be controlled, then the NOx issue might be cured. Cat also reasoned that if the combustion cycle could be controlled to provide a smoother burn rate, a quieter engine would be created. Caterpillar already had information on the rate of speed that the complete cycle needed to achieve a “good” burn. As a result, Caterpillar went in the direction of injecting fuel in 3 stages along with having 2 turbochargers per engine. Timing of these injections was determined by computer with engine load, engine demand, crankshaft position, throttle position and air temperature being the variables computed to determine the injection intervals. These variables also influence the choice of which turbocharger to use. The Caterpillar method goes like this:
• Before the piston achieves the position called Top Dead Center, a small amount of fuel is squirted into the combustion chamber. This will have the effect of reducing the temperature in the cylinder but will also start the combustion process at the same time.
• When the piston achieves Top Dead Center, the main fuel charge is injected into the combustion chamber. At this time, the fuel fully ignites and the power if the fuel is released. With the pilot charge already burning the pilot fuel amount, the actual rate of combustion is somewhat slower that what has been experienced in the past. This actually leads to less “clatter” associated with diesel engines. It should be noted that the temperatures in the chamber are rising at this point into the temperature range of NOx creation.
• Past Top Dead Center, a third charge of fuel is added to the combustion chamber. Again, the temperature is lowered below the critical NOx creation temperature and a slightly longer combustion time is created.

The disadvantages to this system are cost, weight, and PM. The PM is handled by the installation of a catalytic converter that Cat believes will last the life of the engine. Cat also installed a second turbocharger on their engines to enhance performance and decrease NOx. Caterpillar is the only company that has used the idea of a 3 charge fuel system. Cummins and Isuzu normally use EGR on their engines but are supplying Dodge and Chevrolet with diesel engines that use a 2 charge system. There is a pilot charge and a main charge as part of the fuel injection cycle. As a result, quieter engines have been achieved with lower NOx.

In the last few years, one method for the raising of the fuel mileage has been to use injectors that create smaller droplets of fuel in the combustion chamber. The reason for this is very simple, the smaller the droplets the more they burn in the short amount of time that they have available. Think of it this way, if you want water to evaporate in a hot room, do you throw in a bucket full as one mass or do you send in the same amount in the same time as a spray? To get the best use, you use a spray. What is the biggest problem in making the spray? Making a nozzle with the smallest holes to make the smallest drops and having a pump with sufficient pressure to get the same amount of water into the room in the same amount of time.

Let us take that idea and apply it to diesel engines. We want smaller drops, make the holes smaller. We want the same amount of fuel to go in because fuel means power. Make more holes. But more holes did not solve the whole problem nor create the necessary “fog” for the best combustion. Increase the pressure. This “increase the pressure” idea has lead to the creation of injectors that are pumping fuel into the engines in the area of 30,000 psi. While the idea of increased pressure has brought about better combustion, replacement costs of the injectors must be considered as part of the life-cycle cost of the engine. Another thing to consider is the need to keep these injectors clean. Because these holes are so small, it does not take much to plug them resulting in loss of power, increased fuel consumption, and all the rest. This has created some interesting problems for the engine manufacturers and the types of metals being used in the fuel pumps, injectors, cam shafts, cam rocker arms, and rollers. Premature and catastrophic failure of parts is on the rise and while some of it can be attributed to inadequate lubrication another proportion must be blamed on materials.

Yes, so let the people decide, don't try and force it with higher prices (which liberals will then ***** about oil companies making too much money)

When I just have to go to the office or shop, or just beat around town, I drive my little Toyota pick up, or ride one of my BMX bicycles, when I have to go see clients I'll drive the C4, but mostly been driving the Toy or the bike. And since the company pays for most of my gas while working, it was me who made the choice, and I tell you, the C4 and the company 3500 are much more fun and comfortable than the little truck.

Lube-

Like your ideas. The stratified charge that Cat is using sounds very much like the stratified charge that Honda used in the CVCC. The goal of that engine, of course, was to meet CA emissions without the benefit of a cat. Considering though that CAT is mainly supplying engines for large trucks, which are governed by an entirely different air quality standard, how pertinent is this for passenger cars?

European manufacturers will say that Urea injection is the solution to NOx...but that probably won't work for small vehicles where there is no room for a 15 gallon of "urea" solution.

I also know that arvin-meritor is working on a "Plasmatron" which is a super high heat chamber that excites the NOx so that the chemical bonds are broken. Still years away.

the USofA is just plain proof that the people will not decide to buy fuel economical cars on their own...
it's only recently that things started improving, and basically that's just because of legislation , not because the demand for fuel ecnomy urged car makers to produce economical cars...
the upped prices of oil products is only now starting to become an issue ( or else why did this thread start now instead of couple of years ago ?? )


as for diesels poluting more... think again , modern diesel engines are almost cleaner than petrol engines.. the only thing they put out more , is small particles, and those are currently taken care off by a particle filter , which is becoming standard equipment on more and more cars...

Svan-

Sorry, but this is incorrect. NOx cannot be scrubbed out by a particle filter as it is not a particle. It is a gas.

NOx is a major contributor to smog. Please read Lube's extensive post on this above for a VERY detailed explanation.

Lube actually did mention the use of EGR and the fact that it creates moor sooth ... which then is filtered with the particle filter...

modern Diesel cars are currently equipped with both EGR and particle filters... try a Volkswagen Tdi engine... it has it...

http://www.vw.com/vwcom/content/objects/pdf/engines/complete_specs_TDI.pdf

OBD D, Tier I, catalytic converter, water-cooled EGR system, onboard refueling,vapor recovery (ORVR)

gouvernements in Europe recognize that , and in Holland for example , you get a tax cut if your new diesel has certain enviromental features...


for trucks in Europe , they use another system , called adBlue
don't ask me how it works, all i know it's very much appreciated, certain EU states allready give 5% discount on toll routes if a truck has it

EDIT
more..
http://www.autoalliance.org/innovation/diesel.php

also , Diesel engines get a lot more milage


and check this chart from Renault
it lists their petrol and diesel engines
http://www.sustainability.renault.com/d/d63.htm

the Diesels have less CO2 emissions than the Petrol engines
and again a better milage.
both are Euro3 standards, only some of the petrol engines are euro4, so the difference is very little, and i'm sure the next generation diesel will just as well be Euro4

That is whats so great about living in a free country, we can do as we want :D

your free country isn't as free as others... the US does not have the patent on freedom, despite what some of you guys think... Guantanamo anyone? human rights violations? or is that too touchy subject? and is there too much deniabilty because technically it's not on US soil ? nice...

anyway , i'de say knock yourselves out if you want, but the fact is , the US polution is not bound by lines on a map , and while you guys guzzle away , as the main consumer of energy on the planet...
while other nations basically at least make efforts for sustainable use of resources, and trying to make the existing stuff last longer...
while that all is going on , the fossile fuels keep wasting away

what do you suggest when we approach the last billion barrels? US confiscating everything at gun point?? do you really think the Saudi's will not sell to the highest bidder? or do you assume that country can be invaded and "liberated" as well? good luck , i'de like to see that happen , would be very entertaining for us Europeans , the extremists hate the US allready , but that would just drive em completely over the edge...are you ready for that? having more and more muslims turn fanatical, while they are allready within your borders? why not give them free bomb training while you're at it...

Your idea of freedom is skewed. The US is no more 'free' than the Netherlands, Germany, Britain, etc.

As Motion says, freedom and social and ecological responsibility are NOT mutually exclusive concepts. Think about it,

ianc

Terrorist don't deserve rights. See who is the first to come help your country when a terrorist attack occurs there!!

China belches out much more pollution than the good old USA, as do many other countries, but you choose to ignor that fact.