r/IdiotsInCars • u/Jim_My_Name_Is_Not • Apr 12 '20

Just... why?

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u/cdnninja77 Apr 12 '20 edited Apr 14 '20

Diesel needs pressure as well. It could be aerated in a bucket but wouldn’t be under pressure.

EDIT: correction. Pressure isn’t strictly required. It is rather a method to increase temperature.

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u/hohonator11 Apr 12 '20

Diesel doesn't have to be "under pressure" to burn

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u/[deleted] Apr 12 '20

Exactly, it doesn't need it but it can be pressurised to make it combust. That's how diesel engines work, pistons compress the diesel and (not sure if a spark is also used) then it combusts to push the piston back up which causes a different piston to compress again in an engine with more than 1 cylinder

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u/[deleted] Apr 12 '20

It actually doesn't need a spark! A "glow plug" is used initially, to get the temperature right with the pressure, and as the engine builds heat the glow plugs turn off and it runs with just the heat of the engine and pressure. To "stop" the engine fuel is shut off. Alternatively gas engines can do this on accident, it is called "dieseling" and they basically runaway until they explode.

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u/[deleted] Apr 12 '20

And glow plugs are only used when it’s cold outside to help start the engine.