Originally posted by Oeneus:
I guess I am pessimistic because the torque gain is so much more that the hp. I guess I am used to seeing the two numbers resemble each other. Why ? (I'll try to be open minded )



Yeah, if the two are different, you usually expect the HP gain to be larger than the torque, because a completely unrestricted engine will have a sloped HP curve where power is proportional to revs, but a typical engine flattens out at the high end. And as the HP curve levels off, the torque curve drops low in that same region. So something that removes a restriction up there can produce a big spike in HP at the top, but the torque curve is only leveled off without raising the peak.

The best explanation of how a pulley could gain 8 torque is that it reduces waste drag from the water pump and power steering pump, and viscous drag in those cases is going to be nonlinearly proportional to engine speed -- it will affect mostly the high end. So this is exactly the sort of situation where one would expect the torque number to be AT BEST equal to the HP number.

So yeah, maybe we should see the dyno plot, or ideally, re-test the same change and see if the numbers are consistent.