Quote:
Originally Posted by elemein
Let's say I am driving a car with a 1.0 L engine (quite small; a Geo Metro perhaps?) I am cruising at 2000 RPM and have the throttle down at 20%. Let's say that the engine is currently running at 80% Volumetric Efficiency, and, it is also running a bit lean at a 15.5:1 A/F ratio.
How much fuel would I use?
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Hello elemein,
First using 20% throttle and 80% VE is a bit unclear. VE generally means at full throttle. Assuming you mean to find the amount of fuel used at 20% throttle, and also assuming that 20% throttle means that the amount of air (mass of air) being consumed is 20% as much as would be consumed at full throttle, then your math is fine. Assuming 20% as much mass of air makes everything easy, you consider that the air entering is about STP and the density is about 1.2 gm/l So 200 cc (20% of 1l) is 0.24 gm of air.
0.24 * 1000 (rpm/2) = 240 gm per minute. at 15.5:1 A/F gets you 15.4 gm/minute, or 929 gm/hr of fuel. What speed is this Metro making at 2000 rpm? Is that likely 50 km/hr? 929/50=18 gm/km. The density of gasoline is about 750 gm/l so 0.025 l/km or 40 km/l (about 100 mpg)
Or is that 2000 rpm and 20% throttle closer 10 km/hr? Or 100?
-mort