Klean Diesel Kaput

You never know they might be diesel hybrids?

 

You could be onto something there....

A 3 cylinder diesel hybrid with enough battery capacity could make the Prius look like a gas guzzler. They have to meet CAFE requirements somehow.

 

That will change over the next two years not that urea injection is more commonly used to reduce NOX emissions. The DPF and EGR is what killed diesel sales in the US. It cut fuel economy in half or even worse in many cases. Now with Urea injection the mileage is getting back to where it belongs. 2011 superduty test trucks are getting 20-23 mpg hwy. Not bad for an 800lb truck.

Now imagine a Jetta TDI going the same route. You could be looking at 70mpg or better.

 

I'll tell you my experience. Cab drivers in the UK have used diesel engines for years due to the economy and longevity of the engine. However, with the move to lowing more and more harmful emissions the cars have got more and more complex and expensive to fix! High pressure diesel pumps, EGR valves failing every 20k miles, DPFs clogging up etc.

Our taxation system on cars is based on their CO2 emissions so diesels historically have been beneficial compared to a similar petrol model. However, there appears to be a slow move away from diesel, in my line of work at least. Some are going the LPG route and others, like me, are giving hybrids a look. I have asthma a little and as such hate the muck that is spewed out of even the cleaner diesels when under hard acceleration up hills. Air quality is important to me and that is another string in the bow of the Prius.

I'm not completely anti diesel, if you do lots of motorway/highway driving or towing then a diesel would be the way to go. Also, SUV's really suit diesel. The latest Range Rover v8 diesel has masses of torque and pulling power and makes the v8 petrol look like a weakling.

But if you just use your car for a 20 mile commute through heavy start stop traffic then a hybrid and later an EV is probably the way to go.

 

Huh? How did particulate filters kill fuel economy? An apples-to-apples comparison would be the MB E320 TDI. The before DPF edition did not have way better fuel economy than the after DPF edition. How is using urea injection for NOX control causing economy to get 'back to where it belongs'? If anything, the weight of the urea tank and injection technology is exacting a tiny mileage penalty.

I suspect that VW is expecting to see a diesel-electric hybrid that could produce somewhere in the 70 mpg range. They would need that kind of economy to offset the non-economy of their SUVs.

 

more horse hockey from companies trying to appear technologically up to date and hoping to hang on to the few customers they have by talking the bob klutz line.

 

Im sure VWs hybrids will most likely be diesel hybrids, which will get better fuel efficiency than a gas hybrid such as the prius, all things equal the diesel will be more efficient. Now if their hybrid drive robs more power than the Synergy drive, then things will start to get interesting.

Passenger diesel sales from 2007-2009 have decreased for a number of reasons. One is that the TDI was offline for awhile. Another is that the new technology scared many people and did hurt the fuel efficiency as well as increase the cost. Another factor was the price of fuel, its been low and diesel has been more expensive than gasoline. All of these things together made it harder for some to justify diesel power especially since Americans aren't to fond of it as it is.

Many manufacturers eat their own words. Back in the 80s and 90s John Deere bashed Case IHs Axial Flow Rotor combines. Now John Deeres Combine sales are mostly all Rotor combines.

It happens a lot. Its business.

 

I'm not sure a diesel will necessarily be more efficient than an Atkinson cycle gas engine using variable valve timing instead of a throttle plate.

Now if you mean that diesel fuel has a higher energy density than gasoline, that is true, but it doesn't make the engine more efficient.

Tom

 

Urea injection means less EGR can be used, which gives more efficient combustion. It also means fewer active (fuel consuming) DPF regenerations.

 

When I talk efficiency I talk BSFC. Brake Specific Fuel Consumption. the amount of fuel in lbs or grams that it takes to make 1hp or kw for one hour.

The prius has an efficiency rating of 37% which is very good for a gasoline engine, however nearly every single diesel is above 40% with the best being at 54%. The large two stroke diesel made by wartsila that produces 5,600,000 lb-ft of torque.

The added energy in diesel fuel is just one part of the equation of why diesels are as efficient as they are.

 

Anyone know if the diesel hybrid would stop and start the engine like the Prius? If so how would a diesel engine like all those stops and starts. Higher starting torque/currents would be needed and that may cut into efficiency.

 

To add to that even further, manufacturers have been lowering compression and increasing the size of EGR coolers by a lot to lower NOX levels, so now with the SCR getting rid of all of that we can go back to having hotter combustion(more efficient), which in turn reduces the particulate emissions and fuel usage due to a more complete burn.

 

Of particular interest to me are very large Prime Movers that are installed for Combined Heat and Power. In such applications, real efficiency can be 80%, newest designs approach 90%

Why more commercial office buildings, factories, and institutional settings (Hospitals, campus networks, etc) aren't using CHP is really a mystery to me

In such applications, the additional cost of CHP still has a 5-7 year ROI

 

I had one client who completely shutdown their cogen in favor of grid power around 2005. The economics just didn't work out.. I think it was due to the increase in NG prices but I wasn't privy to the exact details.

Another client installed cogen about 8 years ago but doesn't use it as much as they used to. I believe this is also due to fuel prices.

These units are NG because the state is nonattainment for ozone, so if it was #2 you'd have increased emissions, requiring the purchase of additional emission credits in order to avoid strict limitations.

 

That is why I do not compare mpg. A hybrid is just that, take the hyrbid part away from it and its an apples to apples comparison.

This is why I use BSFC it takes all other components of the vehicle out of the question.

 

Yes if the Jetta had a hybrid option the its unlikely the prius would stand a chance in the MPG dept

 

OMFG...whole forums of TDI enthusiasts that will be left dangling in the wind. VW moves to the Dark Side. Some things are simply too sweet to allow to slip into the past.