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Old 02-02-2013, 02:05 AM   #96986
Timmeh!
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Quote:
Originally Posted by suss6052 View Post
Eh, in order to build an engine to handle the elevated compression and to run on compression ignition it has to be much heavier/ thicker cylinder block/ etc.

That tends to hurt the performance and cost far more as compared to a gasoline engine. Never mind the fact that the fuel also costs significantly more per gallon.





In fact Mazda's going the other way adapting gasoline engine technology to a diesel to try and build the lowest compression modern diesel at 14.1 compression.

The key enablers of being able to run a gasoline engine at 12:1 compression on 87 octane fuel are variable valve timing, direct gasoline fuel injection and modern electronic controls.

They have had gasoline engines running at 12:1 or greater in the past, but it absolutely required high octane fuels to prevent detonation/ auto ignition. The liquid fuel injection directly into the chamber has a cooling effect on the compressed air charge during the phase change.

Turbo diesel engines tend to make more torque, but they don't tend to rev as well, nor make as much power as an equivalent displacement gasoline engine.
well yes, much better durability results.

disagree, the 1.9 TDI motor is not bad at all.


Mazda is doing that to reduce NOx so that they don't have to run urea injection because people don't like having to fill up a urea bottle. in europe diesel compression ratios haven't dropped.

the direct injection is NOT for charge cooling, that would be what water/meth injection is for. the direct injection is so that the injection can be timed to prevent detonation, just like a diesel.

Turbo diesels are torquey, but by "power" i assume you mean horsepower, which is a calculated value only related to torque and RPM.

diesel has more energy per unit volume than gasoline, diesels also extract more power from that fuel because they can run super lean without any detonation (again, ignition timing).

The reason diesel is more expensive is because it gets taxed higher, because the majority of diesel is used by semi trucks who tear up the road (hence higher road use taxes on the fuel)

Europe is full of turbo diesels, and for good reason. pound for pound a diesel engine will be more efficient and go farther on a given amount of fuel.

the reason that diesel's aren't popular here is because back in the 70's GM adapted their normal gas big blocks to run on diesel... the extra force of combustion was destroying bottom ends.

Please do some more research before you just come in here and try to explain engine mechanics to me. as far as carbon monoxide emissions, diesels trounce gasoline engines, making them cleaner (especially once you add urea injection/a catalyzer for the NOx and other particulates)
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