I know this is an old post, but I couldn't come across another thread on this topic. I've seen many references to
diesel lowering the octane rating of gasoline. My first instinct was to shout BS, but I'm at least smart enough to know that I know very little about this topic.
Quote:
Originally Posted by Old Tele man
...octane is a figure of merit of the gasolines' resistance to detonation during compression buildup...diesel doesn't have this problem.
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I'm confused as to how it's possible that a diesel engine may have double the compression of a gasoline engine, and not require more resistance to detonation. Many ignition advance curves ignite fuel as much as 30° - 40° BTDC at higher RPMS. If detonation was no big deal, you could continue to advance the timing to the point where ignition of the a/f mixture would actually be working against the motor more than working for it.
I thought that this was what would happen in a diesel engine if you used gasoline. The gasoline would ignite prematurely and cause the engine to work against itself. In the same regard, I thought that diesel fuel required more heat energy to get it going, which is why diesels have such high compression.
Help me out here. what am I missing.