pani_k

iTrader: (1)

On my way home last night, I was just thinking to myself and started to become very curious as to why.

I remembered dismantling a diesel engine because the big ends went. And remember putting it all back together again. I saw the engine design very much similar to petrol engine bar the head in some respects. I started to think but couldnt find an answer. Maybe I've missed something fundamental or its more complicated but the question I want answered:

Why do diesels make the noise that they do? The chuggging noise? The classic dug-uh-dug-uh-duh-uh-duh-uh? What is it that makes them make this noise?

Thanks

Rick

the fact that they are 'dieseling' - you car makes a similar noise if/when it pinks...

Paulo P

The rattling noise is due to the detonation I believe, this is nomally a bad thing on petrol engines but essential on a diesel engine because of how they work.

Trist

a petrol engine has a spark and highly flammible gasses to ignite so its a smoother process, where a diesel uses the heat of the gasses compressed to ignite a less flammible gas so its more aggressive explosion.

Chip

iTrader: (3)

Yep, as above, when the petrol burns, it does so with a moving flame front finding its way through the charge as it goes, on a diesel the whole lot just goes up at once essentially.

So its the difference between a burn and an explosion

pani_k

iTrader: (1)

ahh ok. the fact that a diesel has tonnes more compression contributes highly to the noise

nthorpey

saves typing it out

http://auto.howstuffworks.com/diesel1.htm

AlexF

Define a burn and an explosion then chip

nthorpey

i was always told at Ford there is no explosion it was defined as a 'rapid burn' although who cares in the case of petrol/gas anyway

hai07222

Its caused by little explosions called uncontrolled combustion.

pani_k

iTrader: (1)

so that why diesel engines are getting quieter and quieter? they are making them combust more efficiently hence none of the heavy chugging like the 90s diesels?

you reckon soon they will sound more like a petrol?