I have read in several places how changing your pulleys should give you and increase in hp and allow for a quicker engine response, but what i could not find was hwo these pullieys acutaly help. If anyone can help me out, or if anyone has done this mod and care to give some feedback will be very appreciated, Thanks Fellas.

 

Basic engine 101. Lift your hood and you will see the serpentine belt. The round wheels where the belt sits on are pulleys. The motion of the belt is made by the movement of the crackshaft in your engine which is tied to the larger pulley in the middle. All the components connected by the belt (A/C, power steering, alternator) are pulleys which as they turn provide power to each of the components. Also incidentally, by spinning the pulleys of these other devices takes part of the power produced by your engine. The longer the belt, the more power is taken from your engine to power these devices.

By shortening the pulleys which power them, the faster the belt spins, the faster you reach RPMs. There is programming in the ECM (main computer) which tells your truck when to shift, how much fuel pressure at each RPM, etc. This programming is balanced by the manufacturer and unless you compensate in programming you can do some serious damage. I would NOT recommend changing pulleys & belt unless you know what you are doing and are prepared to take the resulting consequences or the mods are made by someone who does and can warrantee them. There have been some threads about warantee voiding that this would definitely be one of those things since you are changing the way the engine operates.

Just my $0.02.

-Luigi

 

Changing the pullies out is like changing the rear end in a differential, there is an effective change in ratio. The plus side is that the underdrive pullies put less strain on the motor by taking away some of the effort that it takes to spin them at engine speed.

The pulley that receives "power" from the engine is the crank pulley. This turns the belt which turns the other accessories such as powersteering pump, alternator, water pump, etc. By adjusting the size of the pulley you effectively change the ratio (the pullies are normally bigger which slows down the RPM's of the accessory) which in turn takes less HP from the crank pulley to turn. A major downside of having the underdrive pullies is reduced charging from the alternator, especially at idle. The amount of circulation of coolant is also slightly reduced if you change that pulley as well.

Personally, I am not a bid fan of underdrive pullies. If you want to add a cusom look, just get some aluminum light weight pullies so you get the benefit of lower reciprocating mass and a fully charged and cooled truck.

If you are looking for cheap HP, well quit looking as there is none. As the old adage goes...

"Speed costs money, how fast do you want to spend?"

 

Thanks for the info guys, really cleared some questions.
So i better just save up for the Superchip and maybe some gear later.
Thanks Again.