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When I graduated from university in the '80s, around 1000 bar injection pressure was state-of-the-art in the auto industry for HD diesel engines. Well, to be honest, little higher than 1000 bar in some cases (unit injectors). DI had still not entered the LD sector at that time, so injection pressure levels were significantly lower in that application. In a period of little more than 10 years, we went from 1000 to 2000 bar, albeit still not with common rail at that time. Today, state-of-the-art is around 2700 bar and approaching 3000 bar. There is, however, not much more to gain with even higher pressures, since the increased pumping work will offset any gain in combustion. Moreover, DPF has become a "fix" for PM/PN, so we do not need ultra-high pressure for that reason anymore. Thinking about parallels for GDI engines, it is known that higher pressures (than the current level of 200-350 bar) will reduce PN significantly. I recall having seen results for up to 1000 bar in the literature. Eventually, we will also see diminishing gains in trade-offs also for GDI engines as pressures increase. I would not rule out that we could get up to around 1000 bar in the far future, but I cannot see any rationale in a level approaching 3000 bar in this case. Anyhow, it would be unknown territory and several issues could be expected that, in contrast, seems manageable with diesel fuel in the near future. As in the diesel case, one should also realize that the "fix" of using GPF must also be considered. As with DPF, we could have a technology here that will reduce PM/PN to very low levels under any driving conditions. So, why bother with pushing injection pressures to even higher levels (i.e. over 500 bar), or using double injection systems (IDI and DI), if you can have a "fit and forget" solution as GPF? GPFs are not expensive. For sure, GPFs also have some issues but I cannot see much future in doing whatever you can to avoid GPFs. Note that filters (DPF & GPF) will also trap ash, metals and other particles than those that originate from fuel combustion. Some of these particles are very potent and pose health hazards, so they need to be filtered out in any case. But, talking about Delphi and this specific article, for sure, we will see other injection equipment suppliers who will also offer something in the range of 500 bar.
Well, it seems to be similar to abatement of the formation of summer ozone. You have to decrease VOCs. If you decrease NOx, while keeping VOC constant, it might get worse. The so-called "ozone weekend effect" is familiar to many on this forum, I presume. During weekends, when HD traffic (major NOx contributor) is low but LD traffic does not decrease that much, ozone levels are higher than during weekdays. A paradox, if you like! The formation of secondary PM seems to respond in a similar way. I wonder why there is so little effort to control VOCs (i.e. hydrocarbons, HC) from traffic. Particularly during cold starts in cold climate, HC emissions from gasoline cars can increase by more than one order of magnitude compared "normal" ambient temperatures. Today, most of the focus seems to be on abatement of NOx (and PM/PN, to some extent in the EU) but HC (particularly off-cyle) is more or less neglected.
Well, a span of 30k€ to 40k€. This is not really the cheap EV "Folks Wagon" if we recall that a similar car of the same size using a 3-cylinder gasoline engine would cost only little more than 10k€.
I wonder if we have a trend from V to in-line 6-cylinder engines in Europe? The mild 48V hybrid will, most likely, replace conventional ICE powertrains in the near future. This voltage level does not pose a hazard to humans, which simplifies the system. It remains to be seen how far this technology can be stretched in the future. There is not much information on the 12% CO2 improvement but it is not likely that this improvement cannot solely be attributable to the hybrid system.
But with big batteries on-board for a long range, there would be no margin for payload? Minor problem, perhaps...
@Mahonj, It is EU electricity mix. You could do cherry-picking by choosing France or Sweden (or maybe a country with much higher CO2 per kWh than EU mix) but our electricity market is getting more and more integrated here in Europe, so their comparison is fair regarding this aspect. The main conclusion here would be that you would have to focus on cherry-picking to find any real advantage with EVs in Europe. Yet, they are subject to significant subsidies.
@GasperG It does not matter very much if you compare according to WLPT or NEDC, as long as all vehicles are compared in the same driving cycle. My Ford Focus diesel car usually consume less than 4 l/100 km, except maybe a period in the winter time with short distance travel where the consumption increases somewhat, so obviously you can get real-life fuel consumption below 4.2 with a diesel car. I acknowledge that Prius has very low fuel consumption, which would also be on par with an EV. Nevertheless, a diesel engine is even more efficient (at most loads and speeds) and it is appropriate to comment on the same engine as VW cited. Of course, there is more to it. You would not just substitute a DCT gearbox with a hybrid drive but you would also downsize the engine to get the full FC benefit while keeping the performance on at least the same level. Or, even better, reduce the number of cylinders from 4 to 3, with a corresponding gain in cost. I also consider the mild hybrid to give more bang for the buck than the full hybrid. The gain in efficiency would be almost the same as for the full hybrid but the incremental cost would be far lower. Moreover, it would use less rare elements than the full hybrid and in comparison to the EV, the difference would be monumental.
Let´s look at another hypothetical option. We put the TDI engine in a full hybrid drivetrain (e.g. similar to Toyota). No plug-in; just full hybrid. Let´s also assume only moderate improvement by hybridization, i.e. 20% (less than Toyota claims). Simple mathematics then gives us: 140*0.8=112 g/km. Thus, the diesel hybrid would be at least as good as the EV Golf (or better!). This, at a fraction of the incremental cost, compared to a conventional car. What about that? You could, of course, refine the conditions for comparison and calculations but I think this is sufficient to prove some points. Whether you like it or not.
@HarveyD, So, what would you recommend for ocean-going ships to reach your standards for air quality? Battery power???
To protect the environment and human health, GDI should be combined with GPF. Sadly, this is not on the agenda in the USA. In contrast, in the EU, all manufacturers are now in the process of adopting GPF on their new car models.
@HarveyD During the more than 30 years I have been working in this field, vehicle emissions and air quality has improved every year. Yet, the number of people dying from air pollution increase every year. What will happen when the percentage of people who die from air pollution reach more than 100%? Then, we will all die... immediately... or... A group of German pulmonary researchers noted recently that if you apply the same factors for death rate on smokers as we have for population, in relation to the exposure, the smokers would not live more than 2 months. That is obviously not the case and consequently, there must be something fundamentally wrong in these calculations. A debate has now started in Germany. This does not prevent, however, that we now again see yet another ill-founded study published.
We could compare this car with the Mercedes 400 d engine, for example, used in the E class, with an output of 340 hp and 700 Nm. This car accelerates from 0 to 100 km/h in 4,9 s and its fuel consumption is 5.7-6.0 l/100 km. The cars are roughly comparable, and they have similar performance. The Audi engine has a gain of 7 hp and the torque, at 700 Nm, is identical for both engines. Note that the Mercedes engine, at 2.9 liters, is somewhat smaller and already has been in production for some time, so it would not be surprising with an update shortly. The main difference is in the turbocharging. The Mercedes engine has “conventional” turbocharging, albeit twin turbo, while the Audi engine has one turbocharger plus the electric compressor. This, BTW, requires a 48 V electric system. It is difficult to claim that the Audi engine is superior to a twin-turbo “conventional” in-line 6-cylinder engine. However, one could note that opting for a twin-turbo system on a V6 engine would be a concept that is not ideal and would have some significant drawbacks. With three cylinders on each bank, it would be a plumber’s nightmare and it would sacrifice efficiency due to the plumbing. You could perhaps imagine turning cylinder heads to get exhaust manifold(s) in the V of the engine, but this is difficult from a packaging viewpoint. It could perhaps be done on a single turbo engine but hardly on a twin-turbo engine. Well, you could perhaps have one single turbo on each bank (as on some gasoline V8 engines) but that would not give the gain that sequential and two-stage turbocharging has but would be more comparable with a single-stage turbo on an in-line 6-cylinder engine. Two smaller turbos instead of a big one. Faced with the difficulties mentioned, Audi has managed to get a similar result in power density with an additional electric compressor, as for a conventional twin-turbo engine (such as Mercedes). So, where is the progress? Well, perhaps they get somewhat improved drivability due to the low response time of the electrical compressor. It does not show in acceleration performance, but it might give a small improvement in responsiveness. So, what would be needed as the next step in charging of a diesel engine? Well, we have the quad turbo of the BMW 6-cylinder engine as an example. This engine provides 400 hp but the whole system screams for simplification. Something that gives at least as much bang for the buck should be found. I will leave that discussion for later...
@Carl, Yeah, it is stupid that they do not carry out their research on modern vehicles. They seem to want to find something negative in spite of that the current trend actually is the opposite. Should we remove DPFs from in-use cars? I do not think so. Instead, we should put GPFs on (future) gasoline cars. Most manufacturers in the EU actually do that already. For improved air quality and to reduce health effects. Peugeot introduced the first passenger car with DPF in 2000. It was certified to Euro 3. It is a long, long time ago. These cars will not come back and bite us.
Mercedes has the 2,9-liter 400d engine with 340 hp and 700 Nm torque. Performance and fuel consumption in the E-class is similar (slightly better FC, actually for the Mercedes) to the S6. The Mercedes engine has conventional twin-turbo supercharging. So, what makes the Audi engine more advanced than the Mercedes engine? I cannot find a giant leap anywhere. Moreover, the specific power of the twin-turbo Mercedes 4-cylinder engine, at 245 hp, is much higher, so here we have a hint that the conventional twin-turbo technology has more potential also on a 6-cylinder engine. Talking about hybrids... Mercedes already has the 300de.
@SJC Your comment is a little off target... PNGV was a program for light-duty vehicles; not HD vehicles. Nevertheless, it might be interesting in this context to note that all three US car manufacturers worked on downsized 3-cylinder diesel engines with a parallel hybrid drive system for their PNGV cars. Some of the projects actually came pretty close to the FE target of 80 mpg with their prototypes. Moreover, one should note that the prototypes were not SUVs, but instead, more like Porsche Panamera or Tesla Model S in their body shape. Some of us would love to drive such a car today. Technically, it would be feasible. If it would be cost-effective, we could discuss further...
This makes sense regarding air pollution if an HD diesel engine could not ever improve beyond the 2010 status. But, surprise, surprise... technology development is a continuous process and a couple of things have happened under a period of almost 10 years. Today, a state-of-the-art diesel engine can also emit one-tenth of NOx compared to EPA 2010 limit. This has been shown in published literature. Engine manufacturers will, of course, start to certify at this level as soon as the new regulation is enforced. Once again, this illustrates the problem of aiming at a moving target.
This will be the mainstream type of car (also in gasoline version, of course) with ICE and no plug-in features. More expensive cars will come in different parallel hybrid versions but with larger electric machines in general and with an integration of the motor/generator in the transmission rather than belt driven. Will we see the Toyota type of "full hybrids" in this perspective? Well, there could be a niche although the higher end of parallel hybrids will be cheaper and achieve almost the same reduction in fuel consumption as the "full" hybrids. It now appears as PHEVs also compete with full hybrids, primarily due to favorable incentives and promotion from EU via CO2 credits. It is also apparent that full hybrids do not receive as much attention anymore as a few years ago. A Toyota's type of full hybrid is not "fun to drive", with a comparatively large (in contrast to small down-sized turbo engines) screaming naturally-aspirated engine and apparent lack of power. You get the feeling of an outdated concept, although fuel economy remains impressive even at today's standards.
Greenwashing can take care of the dirtiest diapers.
Well, as a Swede, I say that I would like to see this happen first…
@gryf BMW had a 4-cylinder engine but more cylinders will give more power also for a turbocharged engine, albeit not quite as decisive as it is for naturally aspirated engines. Thus, I wanted to give an apples-to-apples comparison with the Audi engine. It is quite clear that the 6-cylinder engines of TAG Porsche and Honda had more potential when it comes to power than the BMW engine. This was also obvious when looking at the podium results in the later years of the turbo era. Please also note that the BMW engine used a stock engine block, which is remarkable. After its championship win, the BMW engine was hanging in for a few more years, but it was not as competitive any more. Nevertheless, the comparison between BMW and Audi is interesting, just because of the number of cylinders, relatively similar cylinder capacity. With multiple turbos, two-stage charging with intercooling and aftercooling, and the fact that cylinders in groups of 3 is advantageous for turbocharging, we could imagine that a V12 1.5-liter Formula 1 engine with those features would have been even more powerful. Of course, it would not have been easy to integrate in the chassis. Imagine a something like jet engine with a high-pressure piston engine combustion chamber riding piggy back on it. Fuel efficiency would, of course, suffer for such extreme engines. Alfa did an effort with a V8 but they did not have the resources and probably started too late to become really competitive. By then, the new fuel regulation limited the amount of fuel, which favored engines with fewer cylinders, and this must have hit the Alfa engine pretty hard. And, as indicated, a V8 engine has a couple of drawbacks when it comes to turbocharging, although packaging in the chassis might be a little simpler than for a V12. With changes in the rules, we do not really know the true potential of the most extreme engines. We should also recall that engines during the first turbo era did not run on conventional gasoline. They used chemicals that had little in common with gasoline and the fuel was supplied by chemical companies as, e.g. BASF. The claim of 50% for the Mercedes F1 engine refers to thermal efficiency; not total efficiency. It does not take, e.g. air exchange and friction losses into account. I would also imagine that the pumping work could even be positive with the hybrid turbocharging they use for some engine operating conditions. I would love to see a comprehensive technical paper on efficiency with this engine, but I presume it will not come (if ever…) until after the current era. Nevertheless, a compact (downsized) and efficient turbocharged using some of these features might take fuel efficiency to a whole new level, even compared to the current leader Toyota Prius, while also providing a fun-to-drive factor not really associated with the Prius. However, with the current focus only on electrical drive, we might never know the true potential; as with the first turbo era F1 engines and advanced diesel engines in hybridized drivetrains for passenger cars.
Impressive as this seems, we should recall that BMW squeezed out close to 1000 hp in race trim and around 1500 hp in qualifying (contemporary test benches did not cope with more, so the higher figure is an estimate) from their 1.5-liter 4-cylinder formula 1 engines. Of, course the qualifying version did not last much more than one lap. In addition, we should note that the regulations are different for race cars but nevertheless, an incredible power density is possible with no limits on turbocharging.
NG is cheap in many countries in Europe simply because the tax is lower than for gasoline and diesel.
So, gasoline cars can also have NOx problems... This is almost 3x the number of VW diesels cars in the USA.