[COLVERT]

Interesting thread this.------I'd like to add a bit more about the ignition of petrol diesel in car engines and in the process probably bore the pants off any readers.----

To get maximum power out of the various fuels the correct air to fuel ratio is very important. For the sake of argument let's say around 12/1 air to fuel.

First Mr clf in the above post. You say that fuel hitting a working glow plug will catch alight. Almost certainly so but the mixture would so rich it would produce hardly any power and would also be a slow burn. ( rich mixtures burning, produce the least heat. )


Now back to the enrichment of cold fuels on start up and how and why this is necessary.

The older petrol engines had a manual choke. This was used to enrich the mixture.---When cold petrol was drawn into the engine it did not vapourise well. The petrol molecules were very large and well spaced out. In fact there was so much room between them that the 25,000 volt spark from the plug could actually miss hitting them.------No hit, no flame.

If you go from this micro level back up to the macro level the analogy you can see simply looking up to the sky above you at night. Looking at the milky way there are billions of stars and you might say they must touching each other. However, in fact, there can be tens of thousand of light years between.

( The speed of light being around 186,000 miles per second. )--

The analogy here between stars and fuel is, on the micro level, similar vast spaces exist between petrol molecules.

( the reason why those high voltage sparks miss their mark. ) To overcome this problem many, many more molecules of fuel are added by increasing the amount of fuel going into the engine. It reaches a point that it's impossible for the spark to miss the vastly increased targets.--Result===the engine fires up.------( More in the following post. Lol. )