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The "EPA testing" process begins with the manufacturer: (A) doing "coast down" tests to find a "road load hp (RLHP)" number for the vehicle. Then, they (B) come up with a supposedly equivalent "test load hp (TLHP)" for the dynomometer they used. So, errors in A propagate into B and so on...
The two equations:
RLHP = (A + BV + CV^2)/7.5 ...A,B,C coefficients for "road"
...where:
V = mph
A = lbf
B = lbf/mph
V = lbf/mph^2
TLHP =(A + 50B + 2500C)/7.5 ...F0, F1, F2 coefficients for "test" dyno
_V = 50 mph
F0 = 36.62 (rolling force)
F1 = 0.1461 (rotational force)
F2 = 0.01869 (aero force)
...example from GM data submitted to EPA:
TLHP = (36.62 + 50(0.1461) + 2500(0.01869))/7.5 = 12.1 "test" hp @ 50 mph
Last edited by gone-ot; 12-20-2012 at 09:27 PM..
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