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Old 07-14-2012, 02:20 AM   #6 (permalink)
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Join Date: May 2011
Location: Toronto
Posts: 263

Blueberry - '17 Mazda Mazda3 GS
90 day: 32.56 mpg (US)

EVO - '08 Mitsubishi Evolution MR
90 day: 23.82 mpg (US)
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30 hp X 0.746 = 22.4 Kw. From the second graph, 22.4 Kw at 2500 RPM puts the engine BSFC right at 210 grams / PS / hr. You should be at slightly less than half throttle, say about 16 to 18 inches Hg vacuum.

If you could add one more gear to the transmission to drop the RPM to about 1800 at 65 MPH, the BSFC would improve to 195. Steady state gas mileage would improve by 210 / 195 = 8%.
not sure but im no where near 1/2 throttle. my idle TPS is 14 on scangauge. at highway cruising on flat surface TPS is 20. i think wot is 78 for me.

You can pass in either gear. If you pass at or near WOT, the BSFC decreases to 190 grams/PS/hr in either gear.
doesn't that depend on the gear because the gear determines RPM?

If you stay in top gear, the power increases from 22 Kw to 50 Kw. That should be plenty for most passing. The most efficient passing is with the least increase in speed because you then spend less time at partial throttle (300 BSFC or worse) to slow back down.
im not sure i understand the last part. isnt least increase in speed bad? if i have more load (more throttle) hence faster increase in speed i spend NO time at partial throttle? im sorry im so confused this part! So im gathering that i should pass on final gear at wot vs dropped gears with high rpm and 3/4 throttle?
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