Originally Posted by dually
If you're doing that, might as well eliminate the powersteering, and AC pump... But I highly doubt you will gain that much hp.
incorrect. the water pump must run all the time or you will have overheating problems. you could pull the belt off the power steering pump but i promise you'll want to put it back on after trying to park your truck a few times, and its pump only draws power from the engine when the wheels are turning at a slow enough speed to require steering assistance.
the fan is needed when there is no airflow across the radiator, as in when you are moving slower than about 5MPH, and when the AC is running. The rest of the time it is nothing more than a parasitic drag...and it is proven it eats between 5 and 15 horse, depending on RPM, air density, "clutch" fluid temperature. An electric fan motor usually draws around 15 amps...translates to 180 watts...translates to about 1/4 horsepower more the alternator is going to have to use to make the power to drive the fan. a pretty good trade-off.
The stock fan and its clutch also act like an appx. 10 pound flywheel. Its rotational mass must be increased and decreased with engine RPM. More drag on the system.