Quote:
Originally Posted by Ryancoolwind
I think you guys are mixing up compression ratios and air fuel mixtures. The compression ratio isn't a dynamic number (except the new Nissan variable compression engine). When you momentarily block off an intake, the engine will only run richer due to the remaining air being used up faster then it is replaced. The engine will then stall once the rotating inertia isn't enough to overcome the vacuum in the manifold, or when the mixture is too rich and is unable to burn. Modern diesels have throttle bodies on them for emissions reasons, in certain drive cycles the TB will partially close to better have egr gasses pushed into the intake
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The
dynamic compression ratio is dependent on volumetric efficiency, as normal
static compression ratio is based on a full cylinder worth of air (I should have been clearer). As soon as your cylinder has less than that (which it almost always will to a certain degree as our engines aren't anywhere near 100% VE NA) the effective ratio decreases which is my whole point as restricting too much air into a diesel will stop it working. Nothing to do with A/F ratios as we know diesels will still work spewing huge amounts of smoke
....(sorry to digress)