[bwilson4web]

Hi,

Originally Posted by Old Tele man

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

I remember stumbling across the EPA page that had many of these values for different model cars. Do you have a URL handy or is it in the public domain?

THANK YOU! Found it:
http://www.epa.gov/otaq/tcldata.htm

Having the coefficients makes it possible to compare vehicle, not engine, performance so we can gain a clue.

Thanks,
Bob Wilson