Steve, hi, Two quick questions since this brings back things I was curious about as a child: > > Higher MPG > higher energy density per liter of fuel > higher compression engine (more efficient) > leaner combustion at idle or under low load I seem to remember this as being associated with higher nitrogen oxide emissions than richer-burning. Has that long since been fixed? > better emmisions *except* particulates > Usually are coupled with a turbo (they benefit more than petrol?) I had assumed that this was because petrol engines continue to be spark ignited, not only for manifold injection but even for direct cylinder injection. The flash point of a petrol-air mixture limited the compression ratio you could boost to somewhere below 8:1 (mist of memory), whereas since Diesels (I thought) were timed by when the injection is done, you could compress them as high as you had mechanical tolerance for, continuing to gain efficiency as burn temperatures were increased.
Are those ways of thinking even applicable to the engineering standards today? It’s now been (?) 40 years since these cryptic memories were formed. Best, Eric
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