Quote:
Originally Posted by freebeard
Today I retrieved the MGR that I'd left with an organization called Vintage Underground (they do EV conversion of XKEs). The owner offered to characterize it, but he's out of town and the people who looked at it didn't do any investigation, they rejected it on the grounds that it's geared for 35MPH. Or that power to it is cut at 35MPH.
Paging aeroheaad: 10,000RPM X 6.78 axle ratio is 1475RPM at the 26.6 diameter wheel[?] That appears to be 6.9ft/revolution, but I try to get from ft/minute to miles/hour and I can't obtain a consistent result.
I doubt the clutchless unit adds drag from 35MPH to the Lexus' top speed.
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Using the numbers you provide,
10,000 RPM motor speed
6.78:1 drive ratio
and 26.6" Tire Diameter
10000 RPM divided by 6.78:1 drive ratio = 1474.92625 RPM to the tire.
26.6" diameter tire = 13.3" radius.
Circumference=2xPIxradius, 2·π·13.3≈83.56636 In/Revolution.
83.56636/12 ≈ 6.9642 Ft/Revolution.
1474.92625 RPM x 6.9642 Ft/Revolution ≈ 10271.682 Ft/Min.
10271.682 Ft/Min x 60 Min/Hr ≈ 616300.92 Ft/Hr
616300.92 Ft/Hr / 5280 Ft/Mile ≈ 116.724 MPH
You may have forgotten to convert from Ft/Min to Ft/Hr before converting to MPH. I did the first two times I tried, and I got just over 37 MPH.
I suppose it's possible that they use it only to assist with low-speed acceleration and cut power so it free-wheels above 35 MPH.