clare at snyder dot ontario dot canada wrote in message
...
On Mon, 14 Apr 2008 14:59:35 -0400, "Ed Huntress"
wrote:


clare at snyder dot ontario dot canada wrote in message
news
On Mon, 14 Apr 2008 20:23:23 +0700, Bruce in Bangkok
wrote:


Auto ignition is not how a diesel ignites its fuel. A compression
ignition engine compresses air to above the ignition temperature of
the fuel and then injects the fuel into the preheated air causing the
fuel to ignite.

I hate to be argumentive but I worked in the Indonesian government
Petroleum Labs for a couple of years and I didn;t hear any of the
people from the French Petroleum Institute (who were the main
consultants) compare Octane to Centane ratings. They measure two
different things that apply to two different types of engines.

Octane applies to gasoline powering a spark ignition engine. Centane
applies diesel fuel powering a compression ignition engine. You can
interpolate all you want but I can assure you that in an engine lab
they do not use the compression ignition engine to test for octane
rating nor the spark ignition engines to test for centane rating.


Actually, of 8 different fuels rated (including ethanol, methanol, #2
diesel, gasoline, propane, hydrogen,MTBE and CNG, only TWO are rated
for Cetane.

Here are most of the others:

http://www.naftc.wvu.edu/naftc/data/...datatable.html


And diesel still has no octane.

There is a study I came across that quotes 15 - 25 for the octane range of
diesel #2. I couldn't find enough on it to post it here, because I rarely
quote things that don't have at least two independent sources.

But what does it matter? The issue with diesel is its cetane rating. If it
became useful to measure its octane rating, it would be a simple enough
thing to do: just run it in the designated test engines and see how it
measures up. That is, if you can light it with a spark at all, at those low
compression ratios.

Cetane is much more interesting at the moment because of all of the research
on various types of compression-ignition engines.

An no non-diesel fuel excedes 25% of the cetane requirement for diesel
fuel, with gasoline coming the closest.

Yes, and? What issue are you addressing here?

There are numerous cetane enhancers being used in diesel and other
compression-ignition research, including several that bring LNG and propane
up into the 50 cetane range. But I see nothing in this discussion that makes
it relevant.

--
Ed Huntress