Many years ago I asked about using an underdrive crank pulley on the street to free up a few extra HP. As I recall, there was a lot of mixed feedback on this.

My car has a 26" radiator, OEM shroud, MP clutch fan, a high-volume water pump and 160* thermostat.

With the tire & gear combination I use, highway cruise RPM is 3000++; idle speed is about 1200.

Never had cooling or charging problems in the past using an OEM alternator, and the only real electrical draws are the Crane HI-6 ignition and Mallory 140 fuel pump.

Is it something that could be worth trying, or am I setting myself up for cooling and/or charging issues for the sake of maybe 10 HP?