Wait a minute, that picture shows a fuel tube from the carb area to the cylinder head. I hadn't followed up on the DZ series until now. They are injecting at, low pressure, fuel into the intake port, not the combustion chamber. The fuel pump and regulator are connected to the intake pushrod so that fuel only flows when the intake vavle is open. They still use a needle valve to set fuel mixture and there must be some fuel metering occuring in the throttle body.

Preignition is a problem because it reduces engine power output and increase operating temperatures and stresses. Detonation does the same but much more violent and with more profound results, because the fuel charge explodes rather than burns.

Direct injection in diesels refers to injecting the fuel directly into the combustion chamber.

http://www.me.iastate.edu/biodiesel/Pages/bio14.html

There is a huge difference between diesel injection and gasoline or alcohol fuel injection systems. That is your assignment for tonight.
YS Engines definition is not the same. I don't even know why they are calling it injection. It's an interesting idea. I think they did it to reduce the amount of oil in the crankcase. The oil requirement in the fuel is high 20-24%.

I notice that my FS48 diesel conversion will run fine at WOT for a while than as head temperature rises it starts to knock. It gets progressivley worse until temperture seems to stabilize in a minute or so. I can reduce compression until it doesn't knock, but then it lacks power.

Greg