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vincen · Oct 25, 2009, 04:45 PM

Hi,
I know that when petrol ignites in the combustion chamber of a car's engine there is a force of approx 900-1200psi generated that pushes downward's onto the car's pistons. Can anyone tell me exactly how much force (in psi) is generated when diesel is ignited in a diesel car or truck's engine?

CaptainRich · Oct 25, 2009, 04:52 PM

Originally Posted by vincen

Hi,
I know that when petrol ignites in the combustion chamber of a car's engine there is a force of approx 900-1200psi generated that pushes downward's onto the car's pistons. Can anyone tell me exactly how much force (in psi) is generated when diesel is ignited in a diesel car or truck's engine?

Nothing other than a team of engineers, analyzing your specific engine, can pin-point exactly what forces are being generated. And more than one test would be needed.
Too many variable exsist... like fuel quality and delivery method. Ignition capabilities and compression issues play into the factor, too... yada-yada
Tell me this isn't a homework assignment..

vincen · Oct 25, 2009, 09:32 PM

Put another way, would one expect there to be more explosive force required from a combustion chamber in a diesel engine to move its pistons up and down or less... taking into consideration a diesel engine has a far greater stroke and torque to a petrol engine?

Dragonslayer · Oct 26, 2009, 06:34 AM

Originally Posted by vincen

Put another way, would one expect there to be more explosive force required from a combustion chamber in a diesel engine to move its pistons up and down or less... taking into consideration a diesel engine has a far greater stroke and torque to a petrol engine?

Yes, the compression ratio is much higher thereby creating more torque. Most gas engines are in the area of say 9:1 and many diesels are well over 15:1 Needless to say, it also requires more force to compress the extra volume during the compression stroke.

CaptainRich · Oct 27, 2009, 04:08 AM

Another power revealing clue is the operating range of the two different engines: most conventional engines have a greater RPM band with the torque spread out, whereas a diesel has a much narrower operating and torque band.

vincen · Oct 27, 2009, 02:12 PM

Originally Posted by Dragonslayer

Yes, the compression ratio is much higher thereby creating more torque. Most gas engines are in the area of say 9:1 and many diesels are well over 15:1 Needless to say, it also requires more force to compress the extra volume during the compression stroke.

Thanks for that. I now know that it generates a force of approx 1000psi as well, similar to the force generated onto a car's pistons.