Posted on 12/30/2007 8:51:21 AM PST by saganite
Merging with northbound traffic on Interstate 75 just outside Auburn Hills, Mich., I punch the accelerator, quickly swing left into the passing lane and pull forcefully ahead of the cars around me. In any other ride, on any other gray morning, it’d be just another Interstate moment. But this rush hour, I’m behind the wheel of a preproduction 2009 Volkswagen Jetta, which is powered by a 2.0-liter turbo-charged, direct-injected diesel engine that, even as I leave the speed limit in tatters, is averaging nearly 50 mpg. Equally important, what’s coming out of the tailpipe is no dirtier than the emissions from the 35-mpg econoboxes I can now see in my rearview mirror. Speed, fuel efficiency and minimal emissions? These aren’t characteristics usually associated with diesel-powered vehicles. But they will be.
Most Americans have a bad impression of diesel cars. We think of them as loud, hard to start and foul-smelling. We sneer at them for lacking the get-up-and-go of their gasoline-powered cousins. And we dislike them for their perceived environmental sins, chiefly the polluting brew of sulfur and nitrogen compounds that they emit into the atmosphere. All those complaints were fair a generation ago, when the twin energy crises of the 1970s propelled diesels into national popularity and kept them there for a decade. Back then, many drivers ignored diesel’s faults, or were unaware of them, because diesel cars ran 30 percent farther on a gallon of fuel than similar gasoline-powered cars. It felt savvy to buy a diesel, even daring. Then fuel prices dropped in the mid-1980s, and drivers abandoned their clattering, odoriferous fuel sippers. They went back to gasoline.
Today, diesel powertrains are on the map again, for both car manufacturers and efficiency-minded drivers. The technology could be here to stay, even if fuel prices (improbably) decline. .
(Excerpt) Read more at popularmechanics.com ...
True Diesel Engines run on any thing that is Greasy.
barbra ann
The term suck was used as part of the prior joke, the actual term is vacuum. The function is to increase the amount of vacuum and there by increase the amount of air forced into the compression chamber. The point of above a certain speed depends on whether are not you have what is called a waste gate on your turbo. But as stated the air filter and exhaust also have a part to play.
And Rudolf Diesel’s engine can be run on straight used vegetable oil from restaurant fryolators if poured through a 10-micron paper filter into a secondary, heated fuel tank. That’s great mileage on free fuel. e.g.: greasecar.com
And Rudolf Diesel’s engine can be run on straight used vegetable oil from restaurant fryolators if poured through a 10-micron paper filter into a secondary, heated fuel tank. That’s great mileage on free fuel. e.g.: greasecar.com
Riddle me this, Batman. How do you maintain the proper stoichiometric ratio? I know how it's done with gasoline engines with both carburetors (shudder) and fuel injection. I just don't understand how it's done with diesel.
You left-coast folks much be lucky. I have been all over Arkansas, Mississippi, Louisiana, and Eastern and Central Texas and never once saw such a sticker. Every pump still was the “Low Sulfur not for use in 2007 or later vehicles” variety.
In addition - I actually was casually shopping for a car about 6 months back - and was really interested in a Jetta or Passat TDi. I noticed that they had none, so I asked.... The response was that VW was not importing any until after the 1st of the year because of the “new diesel regulations” - and the fuel isn’t widely available. I emailed VW thinking this was a crock excuse - and the reply was rather vague but did seem to support the answer I got. Wish I had saved it.
I think California has required the use of the Ultra-Low sulfur fuel for some time now... thus the reason for the availability there.
WE are not taking race cars here. Show me a picture of a stock diesel truck are car with a hood scoop. What happens with and on a race motor is completely different in varying degrees than on a stock car. Could you show me where a discussion about fuel efficiency went to race cars and motor.
As far as the four east coast states, well screw em too if they don't want a diesel powered vehicle!
Seems to me that if really efficient cars were available in mass, with obvious advantages of fuel mileage, longivity, low emissions, the availability of such vehicles in 49 states would make the loss of sales in California unimportant to the manufacturers.
Its the fireing sequence multiple of 4,V8 ignite two pistons at a time. Engines run in 4 strokes that produce vibration and equal energy lost to produce the them, 5 or 6 cylinder help overcame unuseful strock inertia. That why in F1, V10 became standard it runs more efficient that a V8 or V12.
An over square engine and an undersquare engine, both having the same compression ratio, have exactly the same expansion ratio. Bore to stroke ratios have nothing to do with expansion ratios.
V8 motors typically do not have counter rotating balance shafts. V6 motors do.
The harmful vibrations in a crank shaft are not torsional vibrations, they are bending vibrations. Adding more main bearings DOES alleviate this problem.
A flat six is superior to a straight six for vibration, bending, and rocking forces. There are no commercial diesel flat six motors. So your theory about straight sixes being superior to v8s simply because there are more of them available(empirical) doesnt hold water.
As for your water pump discussion, you could also increase RPM instead of increasing shaft size. But this is a pointless discussion because in crankshafts, the controling design criteria is bending, not torsion. And if you think adding pillow blocks doesn’t do any good for shafts loaded in torsion only, then take out half of your bearings in your pump shafts and see what happens.
Lots of diesel around here - and not a single ultra-low sulfur pump that I can find. Every pump still has the “not for use in 2007 or later diesel vehicles” sticker, including the local MFA dealer (who sells E85).
I will keep my eyes open...but so far, no scores. I sure would hate to be driving a newer diesel and need fuel around here!!
Well, not liquid soap.
The scoop is a factory item behind the grill on a chevy2500, go look next time you are at wallyworld.
They can be cleaned up so they work properly. NOT a race car.
This is another BIG reason why the diesel cycle is superior to the Otto cycle: the diesel engine, by virtue of compression ignition, does not need a fixed stoichiometric air:fuel ratio. At idle, a diesel engine might has a air:fuel ratio of 60:1 - or more. At full load, a diesel engine might have about a 15:1 air:fuel ratio. In tractor pulls, when you see the tractor operator pour on the fuel, he’ll fuel the tractor “just to black” — ie, the point where the exhaust goes black. This is the point at which you’re burning the maximum amount of fuel for the air charge you’re able to push into the engine with the turbo or super charger.
The important thing to remember in a diesel is that because the air charge put into the engine is compressed to achieve a temperature well above the ignition point of the diesel fuel, and it is only at this point when the fuel is injected into the cylinder, the fuel immediately ignites and burns rapidly. The Otto cycle engine isn’t compressing the air charge to a point where the air reaches a point of being able to ignite the fuel mixture immediately upon injection. The air:fuel mixture must be maintained in a proportion where a spark can cause a rapid explosion of the mixture, and this mechanism remains the same regardless of how much load is put onto the engine.
Well, the heat is scavenged in that it is energy used to turn the turbo. There’s two forms of energy coming out of the primary combustion cycle - heat and pressure.
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