Diesel Engines

[Hopkirk]

How does a diesel engine make the fuel ignite at precisely the right moment, without spark plugs?

[tonyav]

Compression, Hopkirk.

[Hopkirk]

Compression may cause the ignition, but what stops it happening before the piston has reached the top?

[tonyav]

https://www.youtube.com/watch?v=s2WGFELXPNg

[SlackAlice]

This might help

[Hopkirk]

Ah, I see. It looks like the fuel isn't injected until the piston is already at the top - unlike a petrol engine when it goes in before the compression stroke.

Is that correct?

[ABerrant]

Correct

[DTCwordfan]

you have it there.....

[Orderlimit]

Some test results i was reading recently showed the ignition fuel being delivered at around 4 degree before the piston reaches top dead centre which is apparently common.

[Hopkirk]

Thanks everyone.

I was mystified, as I always thought it was like a petrol engine - with fuel injected before the compression.

I can see clearly now.

[EDDIE51]

It is the compression that causes the ignition in a diesel. They are also known as 'compression-ignition' engines. The first diesel's ran on powdered coal! ( bet that gave a few problems with the injectors!)