Unfortunately, no.

Diesel- Low end torque and limited revs
Electric- Low end torque and limited revs
Atkinson gas- High end power and diminished low end torque

Removing forced induction from a diesel makes it run like a tractor, or industrial engine: All low end and no flexibility. Adding an electric assist enhances low end even further but does little for the inherent characteristic of both: Limited rev range and a concentration of torque on the low end.

Atkinson cycling adds efficiency but robs low end torque. Adding electric assist adds low end torque. That, basically, is why gas-electric hybrids work well when set up that way.

 

...PM motors produce constant torque over a wide range. I believe our Atkinson cycle engines are not powerful or efficient at high RPMs!

 

1988 Denver standard Diesel City bus - all stop & go = 1 MPG of diesel.
1996 Denver HYBRID-Electric Diesel City bus - all stop & go = 4 MPG.

Denver was the first city in the nation to purchase a fleet of hybrid vehicles.
And they were buses! ( and they are still using them in 2007 )
-John

 

It's sort of the opposite, actually. Atkinson cycle engines do have a lower top end but they perform better when revving. It's at low revs where the power loss is most apparent.

How this works in the "real world" becomes clear if ever your FEH runs only on ICE with no battery power. If this happens it really demonstrates the shortcomings of the unassisted Atkinson engine. Press the pedal and, instead of the response you're used to, the ICE comes on instantly and revs to about 2500-3000 RPM. Acceleration under these conditions is best described as "liesurely".

 

OK!

However, post 14 indicates significant MPG improvement with a hybrid diesel. And, Caterpillar has experimented with a hydro-pneumatic type hybrid diesel. These facts make me believe a Diesel hybrid will can provide excellent MPG.

 

The EPA cracked down on diesel emissions (which had been largely ignored for years) and it was no longer effective to produce diesels in passenger cars that could pass emissions.

However, with the new low-sulpher diesel fuels, it is now possible to make diesels that pass emissions once again. I think VW plans to introduce a diesel Jetta again in 2008.

I know someone who owns an old diesel VW Rabbit (not sure of the year - I think it's late 70s or early 80s, but it's fairly old). Back when he bought it, diesel fuel was selling for a lot less than gasoline AND the car gets about 40 mpg. So not only was he getting fantastically good fuel economy compared to other cars of the era, but he was getting his fuel at a fraction of the price of gas -- it was a fantastic good deal. Diesel fuel is no longer the bargain it used to be back then, but at least the price is somewhat in line with the cost of gasoline. Not long ago, diesel was selling for more than premium gasoline -- so owning a diesel wouldn't necessarily be a bargain.

The other issue I'd worry about is the high-compression ratio of diesels compared to gasoline engines. There's a lot more stress required to start a diesel and I'm wondering the very frequent engine start/stop would wear on the car as well as how the full-hybrid (being able to start an engine at high speed) would work.

 

I don't want to start an argument but I'm not sure the Denver bus mileage numbers are correct. Most big city diesel buses get about 4 mpg. The official Chicago number is 3.8 mpg. I doubt that Denver would be worse. Also, I think the Denver hybrid buses are natural gas powered (may be either diesel or IC natural gas) so they wouldn't directly compare to the conventional diesels.

A diesel hybrid should work just fine. You might not even cycle the engine off so often since an idling diesel uses so little fuel. However, I would expect to see diesels used in plug in series hybrids where the engine could be run only at the design point speed.

My previous post my have been misinterpreted. The logic problem with a diesel hybrid is that you would be adding a second expensive technology to a vehicle that already has improved economy.

Consider this example with hypothetical numbers. I replaced a Town & Country (23 mpg) with a FEH (33mpg). It used to take me 4.3 gallons of gas to drive 100 miles. Now it takes me 3 gallons. I save 1.3 gallons for each 100 miles I drive. Let's say there is diesel option for the hybrid for about the same added price as the hybrid option and it will boost the car to 43 mpg - another 10 mpg. Now I can use only 2.3 gallons of gas for 100 miles. However, the diesel option, although it gave me another 10 mpg, saves me only half the addtional fuel.

The total gas savings would be better if someone else (perhaps a highway driver) spent the additional money for a diesel only version so he would increase to 33 (or more) mpg.

This is why I think the criticism of the GM "mild hybrids" is misplaced. A 5-10% increase in mileage for 15 mpg trucks and SUVs will save as much gas as a 30% increase in mileage for 35 - 40 mpg small sedans. I also think this why the FEH is really so significant (if we could get more built) because the FEH is replacing Explorers and minivans while the Prius/Civic is replacing Corollas/Civics.

 

The hybrid buses in Denver are a series design. They run a 2.5 liter Ford industrial engine on CNG at a steady speed, spinning a generator set which charges batteries. A few years ago the fleet was converted from lead acid to to NiMH batteries. They are downtown mall shuttles and thus move at low speeds and generally only go one city block at a time. So they really benefit from the heavy lifting that electric motors provide. The local transit district also has a few GM hybrid buses, but I don't know much about those.

Diesel hybrids have been extensively researched and the companies who done so have not found much promise with them. Two power sources which both produce a lot of low end torque don't make sense to begin with. And a small, direct injected diesel augmented with forced induction is much cheaper and almost identical in economy, all things considered. There's been no one so far who's been able to make a legitimate business case for a diesel-electric hybrid in a relatively small, light family car or truck.

 

A "diesel" bus is the type of engine, not the type of fuel.
You can run a diesel engine on propane or CNG which, IIRC, is what the Denver shuttle busses are. Since they stop every city block, and never exceed about 25 MPH, they did in fact get close to 1 MPG! *( Hybrid now 4 MPG )

This is certainly a "niche" but shows the design works well in certain applications.

 

There is at least one E85 station here--it's at the Navy Exchange in Arlington at Columbia Pike and Hayes Street. The Navy Exchange is typically only for military ID Holders, but the alternative fuels (CNG and E85) are open to the public.

I've been looking into an E85 conversion myself and there are a couple of websites out there that will do it for you or send you the kit:
1) Change2E85: The conversion kit for the Hybrid is the 4VAB-EV6. http://www.change2e85.com/servlet/Detail?no=107 is the kit to order

2) Fuel Flex International: www.fuelflexinternational.com