[Vwdiesel] New to list

Harmon Seaver hseaver at cybershamanix.com
Sun Mar 7 20:23:56 EST 2004

  No, I think you have it figured out right on there. So how about adding
ethanol to the fuel -- would that help?

On Sun, Mar 07, 2004 at 08:15:33PM -0500, Lee Hillsgrove wrote:
> > Lower cetane is lower energy content and thus lower economy.
>   I'm not sure I agree with that statement. The cetane number in diesel is a
> measure of the willingness to ignite, much as the octane number in gasoline
> is a measurement of the resistance to auto-ignition. Large, low-speed
> stationary engines burn stuff with cetane ratings so low our engines
> wouldn't even run on it, yet they deliver phenomenal economy. A fuel with
> low cetane tends to run poorly, smoke more, not start so well in the cold,
> and return less economy in a high-speed diesel more as a function of
> essentially altered injection timing due to the fuel not being so willing to
> ignite. It effectively retards the injection timing. Look at the low-speed
> tractor-trailer sized stuff, they run generally OK on low-quality fuel
> because it has plenty of time to ignite and burn completely. The high-speed
> diesels such as we have in our VWs, on the other hand, require fuel with a
> higher cetane rating due to the comparatively short window of time available
> for the fuel to be injected and burned completely. The TDIs, for example,
> were designed for and really want to see a minimum of 50 cetane fuel such as
> they have almost everywhere else in the world. Because the USA's diesel
> market consists of predominantly low-speed, heavy-duty engines that run on
> low-grade fuel, that's what we get. The trucking industry has absolutely no
> incentive to pay extra for fuel that is over and above what their rigs
> require to run, as that would negatively impact profits.
> ...or maybe I'm way off-base. Could be.  :-p
>   Lee
>   Oo-v-oO
>   KB1GNI
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Harmon Seaver	

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