im wanting to order a hughes 30% underdrive pulley. but i was curious as i should do just the crank or the crank and alternator, because i have 2 efans and want the alternator to keep up. so and input would be appreciated. i didnt know if doing the alternator pulley would actually make is charge less at idle

 

E fans + underdrive pulley = charging problems. You need to ask hughes what the alt pulley is for. If its bigger than stock, it will further under feed the systems. If its smaller than stock, it will drive the alt harder at a given rpm and recover some of the loss at the expense of wearing the alt out prematurely.

A larger alt can make up a deficit, but make sure you have a fuse to handle it and you get the correct pulley for your system.

 

What year and engine size are you? Because that makes a BIG difference in the assembly.

For example: 2001 5.9 has a ONE PIECE crank pulley and balancer combo. If you want to run a crank pulley, you need to get ANOTHER bolt on balancer for an earlier model to bolt onto the pulley before installation.

If you have a 5.2, then it is a simple bolt on. If it is a 5.9, check to see if your pulley is a one or two piece. One piece is simple.

Also, does your truck have the off road package? Because they came with 136A alternators. I have that package, so I can run E-fans and an underdrive pulley.

If not, you can get the overdrive alt pulley.

 

Are you sure about that? Underdrive crank pulleys are smaller than stock.

 

He's referring to the alternator pulley. Smaller will increase speed, larger will decrease speed.

 

ah yeah. I got mixed up and forgot the rule didn't apply to the other pulleys. Just the crank pulley is the one you want to be smaller.

 

Side question:
If you owned a 3 piece pulley set (Alt, Water, Crank) would it be worth it for me to get a NEW water pump (Non pressed on pulley) to gain a bit extra from slowing down the water pump? I know people will say cooling issues, but sometimes underdriving the water pump actually helps because the fluid sits in the rad a bit longer. However, my truck runs super cool. Always has. Even before the 180* stat. Unless I am using full AC and it is 100* out.

Also, take into account finding the size of belt that you would need if you UDd the crank AND water, but not alt.

 

underdriving the waterpump (even more) would net you a bit of power, whether you would notice it or not? Good question. Its a centrifugal pump..... not like you are using it to develop a lotta pressure in the system...... Give it a shot, see what happens.

 

It'll also under drive the fan clutch as well, be careful.

 

my truck is a 97 ram 1500 4x4 sport with a 5.9l .. i was just kinda curious if i should run both alt and crank pully or just run crank so i wouldnt screw with the charging.