I just figured something out. The crx in all its incarnations gets approx 1mpg better than its respective civic equiv. (i.e: dx 5spd, dx auto), so ignoring that, the hf in '91 got a combined epa of 50-51mpg. My civic got an epa 35mpg combined with 4spd. If i drive my car with the same restraint it took to get 35mpg with the 4spd, I now get about 42mpg according to my first 230 miles with the hf tranny. If I wanted to close the gap to 50mpg to reach hf territory, the engine would account for the other half. So hf tranny/8v really are an even split in fe advantage. This all assumes that the real secret does NOT lie in lightweight rear drums.
ha there's a guy on redpepperracing, his name is Scott, he lives and dies with the praise of '86-87 CRX HF aluminum drums, trying to convert the Integra rear disk swappers of their blasphemous ways. Mak
'85 CRX Si Original EW3 @ 254k...suck it Detroit
'89 CRX HF-Z1 ~ When haste is needed
'97 Civic DX Hatch ~ Formerly 600hp, now 0hp, soon 115hp.