Attention: TDR Forum Junkies Here is why you want a noisy diesel.
From an engineering standpoint, the diesel thermodynamic cycle is not as efficient as the gasoline (Otto) cycle. This is because in the diesel cycle, heat is added at constant pressure (when the injector sprays, the piston is on its way down) instead of at constant volume ias in a spark ignition engine where the piston is stationary and the heat is added all at once.
Diesels make up for this inefficiency by having much higher compression ratios and a much more precise fuel delivery system. However, diesel engineers make every attempt to have the heat added to the diesel cycle at constant volume like a spark ignition engine, thereby increasing its thermodynamic efficiency.
The most efficient diesels are noisy because the engineering tries to duplicate the Otto cycle by injecting very rapicly and adding heat at constant volume. This is the optimum scenario for timing and efficiency and makes lots of noise. The engine must be constructed very strong because there are almost catastrophic events taking place above the piston. Really well built diesels like the Cummins and Cats are very capable of dealing with these pressures. To be sure, the limiting factors for some diesels involve cylinder pressures, but good engineering like we have with the Cummins can deal with it.
Those of you that believe that pilot injection and the other changes are for meeting emissions standards are correct.
If you really think quieter is better, I have a bridge in Brooklyn that you need to buy.
Harry
From an engineering standpoint, the diesel thermodynamic cycle is not as efficient as the gasoline (Otto) cycle. This is because in the diesel cycle, heat is added at constant pressure (when the injector sprays, the piston is on its way down) instead of at constant volume ias in a spark ignition engine where the piston is stationary and the heat is added all at once.
Diesels make up for this inefficiency by having much higher compression ratios and a much more precise fuel delivery system. However, diesel engineers make every attempt to have the heat added to the diesel cycle at constant volume like a spark ignition engine, thereby increasing its thermodynamic efficiency.
The most efficient diesels are noisy because the engineering tries to duplicate the Otto cycle by injecting very rapicly and adding heat at constant volume. This is the optimum scenario for timing and efficiency and makes lots of noise. The engine must be constructed very strong because there are almost catastrophic events taking place above the piston. Really well built diesels like the Cummins and Cats are very capable of dealing with these pressures. To be sure, the limiting factors for some diesels involve cylinder pressures, but good engineering like we have with the Cummins can deal with it.
Those of you that believe that pilot injection and the other changes are for meeting emissions standards are correct.
If you really think quieter is better, I have a bridge in Brooklyn that you need to buy.
Harry
