What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[mikeyss]

I have been toying with the idea of OVERdriving the alternator because when my K5L fans run on hi, my voltage gauge is around 12V. I can't imagine what UNDERdrivig would do to the charging system.

 

[swathdiver]

I have been toying with the idea of OVERdriving the alternator because when my K5L fans run on hi, my voltage gauge is around 12V. I can't imagine what UNDERdrivig would do to the charging system.

It's never for very long, the computer is watching the voltage too.

 

[PPV12HOE]

Installed my Powerbond 25% underdrive balancer with an ARP crankbolt.

Badass power mod for the money and time. You can find them for under $250 and only takes about 45 minutes to install......that includes removing/installing the starter.

They're supposed to be good for 13rwhp........the dyno should say on Monday. I will say the butt dyno and going sideways says there is power there

Did you remove the starter to access the flex plate to torque the bolt...?

 

[gooffeyguy]

I have underdrive pulley sets on both of my mustangs. Usually it's a set, because with a smaller crank pulley you will overdrive the other accessories like water pump and alternator. I know our trucks computer controls the alternator charge, so maybe that won't be a problem, but when the engine is in the higher rpms it may spin the alternator or water pump more than it's actually capable of and have a shortened life span or cause cavitation.

Just things to consider

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[avalonandl]

I would not overdrive the alt. Put a 180 or 210 amp alt on...

 

[mikeyss]

I would not overdrive the alt. Put a 180 or 210 amp alt on...

I like different opinions, why would you not overdrive the alt?

 

[kbuskill]

I like different opinions, why would you not overdrive the alt?

I know that on my old Esky I had the 160A alternator rebuilt into a 200A and it didn't like to charge at idle.

I was going to have my buddy rewind it to 260A but he said the bigger you go the less it will charge at idle.

The solution for me was to swap to a smaller pulley on the alternator which alleviated the idle charge problem.

I had also converted the mechanical fan over to dual electric fans on that truck which caused more current draw, obviously.

 

[Tonyrodz]

I know that on my old Esky I had the 160A alternator rebuilt into a 200A and it didn't like to charge at idle.

I was going to have my buddy rewind it to 260A but he said the bigger you go the less it will charge at idle.

The solution for me was to swap to a smaller pulley on the alternator which alleviated the idle charge problem.

I had also converted the mechanical fan over to dual electric fans on that truck which caused more current draw, obviously.

Did you turn the fans on through the pcm or a switch?

 

[kbuskill]

Did you turn the fans on through the pcm or a switch?

I just wired one to a thermostatic controller and the other one I hooked to a relay that was controlled by the A/C compressor.

Freed up some HP and improved MPG... win, win.

 

[Tonyrodz]

I just wired one to a thermostatic controller and the other one I hooked to a relay that was controlled by the A/C compressor.

Freed up some HP and improved MPG... win, win.

Would you happen to have a diagram to do that? Along with which thermostatic switch you used? I have my fans just sitting in my garage. I'd like to finally get rid of my clutch fans.