Fuel injection technology for small diesel engines has now moved into the realms of electronically controlled 'common rail' systems. The rail in question is little more than a highly pressurised tube that acts as a reservoir, feeding all cylinders. Pressure is provided by a separate pump, usually mechanical but can be electrical. Apart from the rail's ability to provide very high pressure fuel right where it's needed, ie: atop the injector (thereby doing away with pressure pulse and other problems inherent in old style pump-line-nozzle designs) clever lock-out valve technology allows that pressure to be retained when the engine is shut down. This means full injection pressure is available during slow-speed cranking on that inevitable cold-n-frosty morning. This solves much of the age-old problems of cold-starting light 'high-speed' diesel engines, especially those designed around indirect injection (idi) combustion chambers.
The injectors have become electronically controlled, and far more efficient (and hardy) than ever they were. Electronic control means the start and end of injection can be advanced or retarded as necessary for optimal performance, whether cold starting or in the cruise. The volume of fuel injected can also be varied, both by the length of the injection period - controlled by the former two parameters - and by something called flow volume control, in other words, opening the tap a bit more.
Cold weather effects diesel fuel proper, but Jet A1 lacks the full wax content and is treated with inhibitors to keep the wax at bay. Don't go putting conventional diesel fuel in your aeroplane. Apart from it being a lot more expensive, the whole engine has been set up to work best on Jet A1. Always remember that the fuel in any compression-ignition engine is doing three jobs: 1) it's a fuel, 2) it's a coolant for the components pumping it and the electronics controlling its flow (yes really), and 3) it's a lubricant for those same mechnical components - eg: the injectors.
I'd love to see a diesel R44. Just think...a modern helicopter with a modern piston engine, FADEC, three times the endurance, etc, etc.
