Quote:
Originally Posted by Hubert Farnsworth
Again this is where the part open throttle engine curves get really messy when talking about bsfc, its easiest to represent them as contour maps or islands of efficiency, speaking of which no one has located one for the 4a-fe either, but that's not relevant to this topic, however at reduced loads the engine makes less power but may not be operating at its most efficient state, other optimizations non withstanding. However does lower power output lead to lower fuel consumption if the combustion events are still occurring as frequently as ever? I guess as a mechanical engineering student who has only just begun to get into the exciting powertrain classes this is still a bit fresh theoretically vs physical experience.
Also my car probably has the C50 5-Speed Manual Transmission
Gear ratios for this transmission.
1st 2nd 3rd 4th 5th Reverse Final
3.545 1.904 1.310 0.969 0.815 3.250 3.722
At least it was used on the equivalent corollas and some of my research indicates that it may be the same as in my car. that 0.82 overdrive is why its still spinning quicker than is desired, peak torque is closer to 2-2.5k iirc.
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Hubert,I think the aero/BSFC info you need was covered in Hucho's book and earlier by Gino Sovran at GM in his SAE Paper.
Both works deal with maximizing mpg after drag reduction by gear-matching to maintain the engine on the island of highest BSFC.
As early as 1934,Chrysler's Carl Breer realized that to get the biggest bang for the streamlining buck,a car would need to have taller gears to get the 'load' back up and prevent over-revving of the engine.
The best BSFC is generally said to occur at the torque-peak rpm.If so,then,after aero mods you'd want your 'cruise' rpm to reflect that engine parameter.