Hank what if you put them on the crank?

Im thinking of leaving the AC out of the loop to save some drag too.

 

Yea i would bet that hank is correct about freeing the power on the A/C and power steering but i would like to add the fan to that list. The expensive kits have several pulleys, one for each device. They claim to have the stock rate on the alternator and reduce the power steering and A/C extra. When i am parked at a light in the summer with the air on i cant crank the stereo, my amps will brown out if the volume is high enough. The crank underdrive is what it is and if you buy one expecting that then everything is cool. when i cruise around town i just leave the blower on the second to highest setting and avoid cranking the music. Its something to be aware of but it doesnt bother me. While at speed everything works exactly as it should and i can crank the music and the A/C without any problems. Also guys the A/C system has a clutch, if its turned off theres almost zero drag on the system so dont bother bypassing it.

 

if you put a underdrive crank pulley on
you need to change the pullies on the alt and water pump
to keep them at the same speed

my best guess from a 'No Fan' test on a 1995 Magnum 5.9V8
is that the unlocked clutch fan slipping in the silicone fluid
uses between .6 and 1.8 hp
to drive the fan at its own set maximum speed of 900 rpm
no matter what the engine rpm is

keep in mind that the 4.7 v8 viscous clutch fan
has less viscous silicone fluid in its clutch
and slips at a lower rpm...around 450
than 3.9/5.2/5.9 or 5.7 v8s

 

I have been told by several people that the A/C pulley spins freely unless the the compressor is actually running. Just an FYI.....

 

Well thanks all for the info. Sounds like they might be a good idea for a truck that will be doing a lot of longer distance driving. Or maybe to complement other mods.

And SurveyGuy if you do more research and find out anything else please post and educate us

 

I havealt crank and water pump underdrives along with bypassing the A/C in the fall thru spring time and i have noticed a difference in how my truck pulls... AND I LIKE IT!!!

 

Really now, I still want to but im going to wait and see if im going to need to tow before i do anything to my pullys just in case they do change things to mich. Dont wanna cause problems towing a project car!

 

Things I've learned about Electric-Fans;..
Huge spike on your elec-system when turning on.
Use relays,..
The higher the CFM rating, the better.
If you use the fan a Pusher, you loose
30% of it's effective air movement.
(Puller is always better).
It will free up a wee-bit of power.
About 2 to 4HP.

(I know this is Apples to oranges but),..
My '91 Mustang GT has a closed front-end, no grill opening
to speak of so, I use a Mark-VIII fan that move more air than
ANY fan that I've come across. 4800 low to 5600 on high.
This thing will hover off the ground when hooked up to a battery!
For me, it's not enough. I run a S-Trim blower on the car and at
16lbs of boost, I'm over heating with the air on in the summer.
so,.. i ALSO use a Hayden 18" fan on the front side of the Rad
for a pusher-fan. (It moves another 2400 CFM). Take away the fact that it
is being used a a pusher, it moves right around 1800 CFM.
It's almost enough. If I'm careful, and I don't go into boost from every stop-
light I'm golden,.. (But there's no fun in that) so, I have to watch closely at
my Temp-gauge all the time or I'll eat a Head-Gasket. Been there, done that
three times already, no-fun.
Now let's go to the Under-Drives;..
Got a big music-maker in your truck?..
Like that cold air blowing out the vents in the summer?..
Sit in a lot of stop & go traffic?..
AND-your gonna run a Electric-Fan?..
Your asking for a no - start with your truck.
The Alt won't keep up.
What's our amp-rating on these trucks?? 60-80-90 amps???
I run a 230 Amp on my mustang and it's just enough to keep up.
Do the Electric-fan,.. Good way to improve your Water-pump life
and, free-up a little HP along with helping your gas mileage.
With our big open grill design, I see no probs using a fan that moves
around 2400 to 2800CFM and staying cool in the summer.
Check out Summit or Jegs. Be-Cool makes a good fan that moves 2950CFM
for a good price.
Want more grunt, get a set of EQ length headers, (shorty's).
You go with Long-tubes and your gonna rob your low-end power.
But remember, your exhaust only flows as well as the rest of your
system. If you bottle it up at the Cats, you've lost the benefits.
Same with your mufflers. Also, run Mandrel-bends on ALL your
piping from the Headers back.
Not a fan of Under-Drives for a daily driver,.. Just my OP.