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I think you have also incorrectly concluded that mixture doesn't matter in a diesel. It does, and it is entirely possible to run a diesel rich, lean, or stoichiometric depending on how you fuel it. Mixture is unrelated to having a throttle or not.
Oh boy...... tv's a wasteland tonight and my chores are done, might as well have some fun. No, I concluded correctly. The stoichiometric rule that applys to gasoline for a clean burn can't really apply to a diesel. The diesel engine doesn't care about the mixture. There's no, oh I'm rich gonna foul a plug or, oh I'm lean gonna burn a valve. In a diesel engine the stoichiometric ratio is all over the map depending on fuel delivery. It can be anywhere from 70-80 to 1 at idle to 25-30 to1 at full load. There is no control over the air entering a diesel engine, that's why you see all the warnings about not using a starting aid, once you squirt glow plug in a can into the intake, you have no control on how fast the engine is going to rev up, there will be no governor control, the governor is in the injection pump and you just bypassed it. If you get a little carried away with the glow plug in a can, that diesel engine will happily spin up until it can't no more which is usually when one or more of the innards places a picture window into the side of the block so you can have a nice view of the internals without the hassle of taking it apart. So that's where those tappets go....
Once before a guy told me a diesel can run lean, I asked him to explain that to me and he couldn't. Maybe you can? Most people think in terms of gasoline when they talk about rich or lean in a diesel engine. In a manner of speaking if you see one belching out black smoke you could say its running rich, after all it is to much fuel for the available air so that could be considered rich condition but a diesel running lean? It's called fuel cutoff and the engine is coming to a stop.
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And to be precise, the amount of air getting into any reciprocating engine (gas or diesel) per stroke is the same at any engine RPM. It's just that a gasoline engine uses a throttle to regulate mass airflow through the engine, while a diesel uses fueling to control mass airflow. (Mass airflow being a fixed function of RPM and physical displacement)
I'm not sure that's completely true, seems like in a gasoline engine with a throttle plate at the intake, air ingested into the engine at idle with throttle plates closed would be considerably less than part or wide open throttle. I'm having a hard time getting that to register, probably because after a couple courses this evening on semi conductors and electronic controls for Perkins engines my brain is a little mushy, I do pretty good with electrical but you start throwing back to back to back resistors in a series circuit then throw a couple more in parallel circuits then ask me what the reading is supposed to be for x 3 resistor in the third of four parallel circuits my brain just kinda froze up.
