Every time he drives by, they start thinking about lunch.
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Every time he drives by, they start thinking about lunch.
*** Posted via a free Usenet account from
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:
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Mahle Piston Set - .50mm Turbo Volkswagen Jetta Diesel Piston Set: List price, $504.68, "our price" $420.56
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Volkswagen Jetta Diesel Cylinder Head Gasket, Reinz: Your Price $29.92
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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."
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.
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.
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.
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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.
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
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