American ww2 diesel starting systems

[greenman407]

Kinda off the normal beaten pass is this subject. I was amazed to find out that the Fleet boats diesel engines were not started using an electric starter motor , like is so prominent today, but used high pressure air, admitted to each cylinder to get the engine spinning. Here is an article about it. What happens if you dont have any high pressure air, say after a depth charge attack, resulting in major damage?
http://www.maritime.org/fleetsub/diesel/chap4.htm#4C

[vital.spark]

Simple, no high pressure air, no engine!

[greenman407]

I was boggling my mind, thinking about how it could work. The only reason it works is because of fuel injection. A carbureted engine would be out of the question because your air pressure would pressurize the intake which(at least at start-up) works off of vacuum. Pressure in the intake would immeasurably upset your air-fuel ratio and prevent ignition. Also the air would blow out through the carburetors. Fuel injection causes fuel to be (squirted) in at the last instant after the contents of the cylinder has been exhausted through the exhaust valve. A very innovative mind came up with this idea.

[greenman407]

Also, it works because it allows the engine cylinder to build up heat so that diesel ignition can occur. In my line of work, the tool of choice is a 4 lb. hammer and a good size cold chisel(well sharpened).Square hole

[Roddersuk]

In a diesel engine the fuel is injected slightly before TDC (commencement of injection) when the air charge is compressed and the heat rise is enough to ignite the injected diesel fuel. Injection is complete as the piston goes past TDC and flame spread begins to force down the piston on its power stroke. If fuel is injected when the cylinder contents have exhausted through the exhaust valve(s) there will be no ignition as the air charge is no longer there to support combustion having been exhausted. Why didn't the US Navy use cartridge starts for their engines as the RN did, or an air start motor?

[Roddersuk]

As for hammers I prefer the 2½lb ball pein, which with a set of tongues formed my trade badge in the REME.

[greenman407]

Nice. If the 4 lb. doesnt cut it, then the "Blue nosed wrench" would be next.