Quote:
Originally Posted by #SaveTheManuals
Of course I'll still be flying blind without the BSFC map, unless the torque/RPM/MPG map published by Toyota is (accurate and) more or less equivalent. In that case, per my annotations below, it sure looks like the most efficient region is between 2,200 - 3,100 RPM, with load between ~76% - ~95%. The sweet spot is 2,700 RPM at 88% load:
76% - 95% load is higher than I expected based on the general consensus around the forums, but I suppose there are always outliers. At some point I'd like to verify or debunk whether I can really drive my car around at 90% load for peak efficiency. That seems a little like having my cake and eating it too. Therefore I'm skeptical of this chart. |
That chart should be accurate. Toyota published a similar one for the sister 2.5L which the EPA tested & verified.
You can convert that thermodynamic efficiency chart to a classic BSFC chart by taking 81.8 and dividing it by the efficiency. E.g. 81.8/.39 = 210 in the peak efficiency island. 81.8/.35 in the "expanded" zone = 234 (which is still quite efficient).
You can convert Nm torque to horsepower with the formula:
Horsepower = Nm x RPM / 7127
or vice versa:
Nm = HP x 7127 / RPM
So if you need to make 20 horsepower to cruise on the freeway at 2000 rpm, that would be ~71 Nm which your engine makes with ~ 35% efficiency at 2000 rpm.