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Old 11-22-2011, 09:28 PM   #12 (permalink)
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Originally Posted by Piwoslaw View Post
From what I've read on these forums (and if I haven't mixed it up), the actual combustion process itself is very close to something like 95% or 99% efficient.
I often question these numbers as they seem to refer to the after cat burn rate, where your fuel gets burnt is more important than how much of it eventually burns. When a typical Detroit motor is running open loop with a 10-12:1 AF ratio 95% of the fuel cannot burn completely in the motor because there isn't enough air.

I am always reminded of the funny cars with the flames coming out of the tailpipe.

Steady state at full operating temperature I don't doubt 95%+ is possible, but during acceleration, warm up or most any other time including idling I doubt anywhere near 95%. Take the cat off a warmed up modern car and take a whiff of the exhaust, if it smells like gas it isn't burning 99%.
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