40 mpg Prius vs 50 mpg European Diesel cars

The Dodge Sprinter has a GVWR of 8550lbs.
http://www-5.dodge.com/vehsuite/VehicleCompare.jsp

Therefore, it is exempt from fuel economy testing (passenger vehicles
over 8500 lbs are excluded) as it is considered a heavy truck, and
probably doesn't have to meet emission requirements either. Same goes
for other popular vehicles like the Ford F-250/350 series and
Excursion, Hummer H1 and H2, Dodge Ram 2500/3500 series, Chevy Suburban
3/4 ton, etc.
http://www.fueleconomy.gov/feg/which_tested.shtml

I'll also note that OSHA has various regulations on diesel exhaust, but
I haven't seen the quite so many for gasoline (mainly just for auto
repair shops or drive-through restaurants).
http://www.osha.gov/SLTC/dieselexhaust/standards.html

 

Every time he drives by, they start thinking about lunch.



*** ***

 

Burning 500 million barrels of it a day would certainly stink the place up.

 

Mmm... onion rings and fish!

Mike

 

"I think you are wrong. Both diesel and petrol engines are built to the
same tolerances and, though engine management for diesels is even more
sophisticated than petrol, the impact on cost is negligible."

Horse... well, feathers.

Why "think" when you can "know"? Google is your friend. Here, let's
look at example parts costs:

===

http://www.drivewire.com/volkswagenparts/catalog/volkswagenjettapistonandcylinder.html

Mahle Piston Set - .50mm
Volkswagen Jetta GLI Piston Set: List price, $311.03, "our price"
$259.19

Mahle Piston Set - .50mm Turbo
Volkswagen Jetta Diesel Piston Set: List price, $504.68, "our price"
$420.56

===

http://www.thepartsbin.com/repsite/volkswagen~cylinder_head_gasket~reparts.html

Volkswagen Golf III GL 4 Cyl Cylinder Head Gasket, Reinz: Your Price
$21.43

Volkswagen Jetta Diesel Cylinder Head Gasket, Reinz: Your Price $29.92

===

These are typical, and reflect significant design, construction,
material and, yes, tolerance differences (especially in the fuel
injection system, where pressures can exceed 2000 psi even in
indirect-injection configurations). If you'd ever seen even an economy
automotive diesel engine stripped down, you'd have an appreciation for
this. And, worldwide, diesel engines are very popular; your conjecture
about relative volumes is incorrect, though certainly they hold in the
U.S.

If you'd look instead of "thinking", you'd find nuggets such as "The
cylinder head for the [VW] turbo diesel uses a different gasket [vs.
the gas model] and is cast from a special stronger alloy. Different
materials are also used for the turbo diesel cylinder head's valves,
valve seats, and combustion pre-chambers."
[http://ep0niks.ctech.ca/vw/eva2/GE01/ch1.3.1.html] and "Although the
forged-steel connecting rods are similar to those used in the
spark-ignition engines, the pistons are of far more robust dimensions
and are totally different in design, since they must be capable of
attaining very high compression pressures and withstanding the loads of
compression ignition. As on other Volkswagen engines, full-floating
piston pins are secured by circlips. The connecting rods for the turbo
diesel engine have greater piston pin clearances, however, and the
piston skirts are notched for clearance with the piston-cooling oil
jets." [http://ep0niks.ctech.ca/vw/eva2/GE01/ch1.3.2.html] and "Diesel
engines and high performance gasoline engines feature an oil cooler
attached to the filter housing through which engine coolant circulates
to help moderate oil temperature."
[http://ep0niks.ctech.ca/vw/eva2/GE01/ch1.1.6.html]

You are correct, however, regarding the lubricity of diesel fuel and
the whole-life lower cost of diesel engines, at least mechanically
(although as I've noted from my experience, the rest of the car can be
just as crappy and have just as short a life as a gasoline model!).
Much depends, of course, on the relative costs of fuel. That varies,
even in a given location. In the '70s diesel fuel was usually
considerably cheaper than gasoline in the U.S. Today it generally
isn't. In Europe today, the relative prices of the two fuels depends
mostly on regional tax policies, since taxes are a much larger
component of fuel costs there than in the U.S. (where they're still
very high compared to, say, oil company profits per gallon).

And you neglect the fact that in conventional (non-hybrid)
installations, diesel engines need all the stuff a Prius doesn't:
alternator, power steering pump, belts and followers, clutch or torque
converter, transmission, shifter and linkage, and so on-- all of which
needs maintenance, the occasional repair, and periodic replacement of
significant components. By comparison, the hybrids need their little
planetary-gear power-split gizmo, two electric motors, and a battery.

 

<And you neglect the fact that in conventional (non-hybrid)
installations, diesel engines need all the stuff a Prius doesn't:
alternator, power steering pump, belts and followers, clutch or torque
converter, transmission, shifter and linkage, and so on-- all of which
needs maintenance, the occasional repair, and periodic replacement of
significant components. By comparison, the hybrids need their little
planetary-gear power-split gizmo, two electric motors, and a battery. >

Well it still finishes up pretty much a line ball for diesel - higher
production costs offset either by greater volume or longer life.

The unanswered question is, assuming we are talking about a form of
diesel which is no more or less polluting than petrol, what is the
relative cost of the fuel - not the cost at the pump but the cost of
production? A relevant factor is whether you can get more or less
diesel (compared with petrol) from the crude. Refining is a black art
and most of the cost differentials around the world as between petrol
and diesel are artifacts of government policies (or that is my
impression anyway).

 

The following link sheds considerable light on relative cost of
production of petrol and diesel. The striking thing is that, for an
given type of crude (and, I suppose, any given refinery) there is an
optimum ratio of the volume of output between the two fuels. Changing
this affects costs directly and, also, indirectly by increasing
pollutant problems which have to be addressed at increased cost.

http://setris.jrc.nl/docs/EUR 21378 EN.pdf

 

Is it really an either/or proposition? I always had the impression
that petrol and diesel fuel came from different fractions in the
catalytic cracking process. Is that not the case?




Geoff

 

You win this point - that is the case if you talk about the natural
raw products in the simple stages of refining.

Now if they want to spend a bunch of energy cracking the heavier
hydrocarbons that would make diesel into lighter ones for gasoline, or
the opposite by combining the light ones to get more diesel out of
that barrel of crude, they can. But while it adjusts their output, it
also adds a bit of cost.

--<< Bruce >>--

 

There was much discussion in this thread about a diesel hybrid

It turns out that GM of all people is way ahead in devloping hybrid
diesel - in buses. the following links tell the story - diesel, hybrid,
regenerative braking - the lot! 60% gain in economy.

www.shadetreemechanic.com/allison_hybrid_drive.htm

www.gm.com/company/gmability/edu_k-12/9-12/fc_energy/hybrid_allison.html

www.hybrid-vehicles.net/gm-allison-hybrid-bus.htm

I owe it to an Australian electronics magazine - Silicon Chip - which
is running an article in its June issue on this GM - Allison project
which is not pie in the sky - the vehicles are operating in various
parts of the US.

 

Except you wouldnt do that for the sake of your engine would you, poor
thing accelerating hard when cold!

Agreed, modern common rails are amazing little creations. Mind you I
manage to average 45 from a carb'd petrol engined small car that is 17
years old so you'd have hoped they could have got a little more out by
now

J

 

When cold the Prius engine speed doesn't change noticeably on even fairly
strong acceleration, like we do going up the hill from our house - that is
done by the electrics. The engine continues to do its warm-up process at
about 1200-1500 rpm. Of course, you wouldn't want to take any present day
car right onto the freeway when cold, that would stress the engine. In a
serial hybrid (not available in production today) it wouldn't matter at all.

Mike