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Staten Island Boat Graveyard | | | Wrecks | ![]() |
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Staten Island Boat Graveyard | | | Wrecks | ![]() |
btw Love your pics
rappa,
Amsterdam
The Netherlands
No, not common rail at all. Common rail is where all injectors are piezoelectric or high speed solenoid high pressure units mounted along a single rail carrying generally over 1000 bar (+14000 psi) pressure. The advantages are that the faster acting piezo injector can use a technique called pilot injection to begin combustion with a limited portion of the fuel before adding the balance of the amount for the cycle. The result is a smoother combustion with some reduction in noise. One simple effect of that is the clatter sound of a common rail engine being a lot less pronounced than a conventional diesel with poppet or unit injectors. A more important effect is that because of the smoother and more controllable combustion characteristics of common rail engines, percussive stress on the bottom end of the engine is drastically reduced. This reduction in stress allows more fuel to be burned (and more power to be produced) with a given size and weight of piston, wrist pin, connecting rod, and crankshaft.
The other advantage of the common rail technology is that the piezo injector valve can switch at a higher fuel pressure, delivering the fuel through a tighter nozzle which atomizes it better, leading to more complete fuel combustion and thus more power out of a given amount of fuel (efficiency!)
This engine does seem to have a single rail fuel distribution manifold which appears to feed individual accumulators for each injector, which would then be driven off of a cam shaft in the engine. This technology is called Unit Injection. This is a reference to how each injector works as an independent unit, developing its own pressure. Distribution rail pressure would be only an amount sufficient to ensure that the unit injectors are not starved of fuel, and would be provided by a gear driven (or possibly electric, though rare) fuel pump.
The principal difference would be that the pressure of the rail is different by at least a factor of 1000, and the injectors on the common rail are electrically fired, not mechanical and cam driven.
Common Rail has just recently found its way into marine applications, including some pretty big stuff, like the Wartsila-Sulzer RTFlex96C, which is the successor to the unit injected RTA96C. The 12RTFlex96C (12 inline) works at around 100 RPM and if I remember correctly has displacement of 1.8 million cubic centimeters per cylinder and power of around 90000 HP. Its family was, as of when I read about if a few years ago, the most efficient internal combustion engine in the world, exceeding 40%. It's also approximately as big as a house. Now find me one of those engines and photograph that!
EMD / cummigs have common rail fuel systems and all moden engines after that
BTW: wish there was more nautical pics on this site, but love it anyway!