2.5 litres?!?

Hello,

I've just been pondering what engine capacity actually means and I can't get my head around it. I have a 2.5 litre N/A diesel engine, so does this mean the total combined capacity of all four cylinders is 2.5 litres? Surely the engine can't burn 2.5 litres of fuel per combustion cycle so exactly how much fuel does my pump inject into the cylinders at one time and why is it necassery to have such a large capacity engine when it may be injecting just as much fuel as a little citroen injects into a smaller 1.4 litre petrol engine?

I'm cofaffled
-Pos

It's the cubic capacity of the full cylinder usually expressed as Bore x Stroke,

Each "pot" is about (just over) 600 cc at max bore - the bigger the bore, the more air (oxygen) it will hold and therefore the more diesel it will cleanly burn. The amount of diesel pushed in in each squirt is approximately (Very approximately in these old inaccurate engines!) in line with the amount of oxygen available in the cylinder (the maximum it will squirt in at full throttle is the amount that will burn cleanly in the amount of oxygen available in one cylinder). The turbo pushes a greater amount of air into the pot which effectively increases the amount of oxygen in the pot which increases the amount of diesel it is capable of cleanly burning and therefore the amount of power it is capable of producing.

Bigger pots hold more air (oxygen) so can burn more diesel in one combustion which equals more power. This starts to fall down over about 800cc as the weight of the actual piston becomes too heavy above this and starts to cause imbalances within the engine.

a 1.1 saxo will burn as much petrol as will burn cleanly in about 275cc of air, so far less than the defender 2.5 (600cc pot) engine.

Oh right thanks for clearing that up for me!

pos said:

yes but surely it can't be burning 2.5 litres of fuel per cycle can it? So why all the extra capacity? Wouldn't it be more in favor of power to have a small capacity with the same amount of fuel injected?

Click to expand...

no coz it needs that amount of air in the pot with it to burn cleanly! Fuel won't burn unless there's oxygen to burn with!

If you want to burn without atmosperic oxygen you have to use an oxygen-rich gel and then you have a space rocket...MING where are ya?

I altered my last post cos I posted it before I read yours! Thanks again!

Post duly altered too to make it look as though i wasnt answering an imaginary question!!! Just lucky i int bin on the wikky tonight else my garbled response would be even harder to understand!

I fancy something to drink