I saw underdrive pulleys at RPM outlet, are they worth it? Will it underrun the accessories too much? Anyone with experience i would appreciate the feedback. Thanks.

 

In a two-pulley system, crank and alternator, there are no drawbacks. When adding the water pump pulley, sometimes the alternator spins too slowly. And over time you will kill the battery and/or alternator. We think pulleys are a great bang for the buck .


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I don't see anything for the 4.7L. All I saw was the 3.9,5.2, and 5.9.

 

We have the 4.7 pulley, pm me if you need a price check .

Thanks Brad

 

What do pulleys do exactly? I know they free up horsepower... but how much, for how much?

 

Underdrive pulley systems increase engine horsepower by reducing the amount of power required to drive external engine accessories. For example, the alternator, power steering, water pump and air compressor rob horsepower from the engine. By replacing factory-sized crank and accessory drive pulleys with a resized pulley, the accessories are slowed, resulting in more horsepower available to the drive wheels. Typically, a set of street pulleys will increase horsepower by 5 to 10, and increase mileage by 1 to 3 MPG. We have not done dyno testing on pulleys, this is what ASP claims from there testing . If you need any price checking please pm me .

 

Won't that rob the rest of the truck it's power as far as the A/C and such?

 

that was my question too.

 

I put one on my 03 4.7L & pulled it off sent in for the rehab & put it on the 05. Goes well with the e-fan & never noticed any loss of elec. power.Have noticed engine revs quicker & pulls harder.

 

If your worried about the A/C not working on a hot summer day go with just a crank pulley not the whole underdrive system .