Quote:
Originally Posted by Ecky
DI engines generally run at the same air fuel ratios, so less fuel isn't being injected.
Something to keep in mind, even if fuel isn't vaporized at all before entering the combustion chamber, as a piston compresses the contents... let's say 10:1. If the intake charge starts at 100F, and is compressed to 1/10 the volume, the temperature inside the combustion chamber will be just under 1,000° F before the spark plug even fires. Once some of the fuel starts burning, the contents of the cylinder can reach 5,000° F.
Without digging any further, I would imagine this would vaporize any gasoline that hasn't already. Anything that failed to burn simply didn't find the oxygen it needed.
I'm all about taller gearing, however. Friction goes down exponentially as RPM decreases. Load goes up, which also helps.
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From everything I have read just like what you said, everything has burned even the heavy fractions. Parts like between the piston and cylinder wall in the ring pack area lack oxygen and their will be some unburnt HC but the percent is less then 2% on average. Plus these unburnt crevices areas need this unburnt HC to help with cooling acting like a heat sink.