Underdrive Pulleys Pro/Cons

[billy_the_kid]

I currently own a 2006 Mustang GT, auto trans. No current mods. I was wondering how the udp would affect the performance of the alternator, ac, waterpump and etc? Will their be any noise or vibration problems? Do I really want to underdrive the waterpump? Will underdriving the alternator affect my lights, maybe dimming or my radio volume? For a daily driven car, is installing udp really worth it? How much horse power increase could I expect?

 

[Herknav]

Just UDPs probably won't be noticed...

I have not heard of anyone having problems with thier alternator that was caused by UDPs, same with the water pump.

 

[Herknav]

Oh, and welcome to the forum.

 

[Charlie Sheen]

I have had no problems with my UDPs.

 

[SoundGuyDave]

I remember ONE guy that had problems with the charging side of things, but I think that was a fluke... I have the Roush UDP setup, and have had zero issues with it, and just added an E-H20 pump. I don't anticipate any issues, since there are lots of people on the forums running that combo without problem.

I will disagree, and will say you will notice it, though. It's not a huge, amazing, instant race-car feel, but it's akin to driving for a while with the AC on, and then turning it off.

 

[Forge]

i had the UDP on my car before i had a aftermarket high powered stereo installed. Worked great. Picked up 3hp and 3 torque with the Steeda kit.

after installing a nice stereo and turbo kit, i needed the extra water and alternator charging, so i took them off.

UNless you want some high powered stereo or worried about heat form a S/C or turbo - get them. You will love them.

 

[Tortuga]

I have the UDPs. Didn't notice a difference. I also have the shaker 1000 set up. I've had it where my laptops plugged into the car for power and the phone and it's had no problems charging the stuff and blowing cold ac.

 

[SoundGuyDave]

As another note, when you do the UDP setup, the crank pulley is smaller in diameter, but the water pump pulley is larger, which yields NO effective water pump impeller speed change. It will have no effect on cooling. The reason a lot of us have gone to the electric pump is for further reduction in parasitic losses. All the udp effectively does is slow down the speed of the AC compressor, alternator and PS pump, and not enough that you will notice a drag on the steering. You will notice a very slight increase in fuel mileage, as well. I picked up around 11 miles range per tank.

 

[Forge]

Dave -
As you sure, when i talked to Steeda, they said the rotation speed of everything was slowed down a small amount. The waterpump pulley size is increased only so the stock belt will fit correctly. I am not sure about the water pump, you may be correct about that one spinning at the same RPM, but i was pretty sure they said it was slowed, but had no adverse effects on the cooling "steeda sales skills at work".

With that in mind, i drove my car in stop and go trafffic in 110 degree weather with over 80 percent humidity and i saw no cooling issues prior to the turbo install.

 

[marcspaz]

Same here. I have the Steeda UDP's. The only issue I have is when it rains, my belt slips a little for the first 120 seconds the car is on. A shade longer if the AC is on right away. I am going to replace the belt with a 2" shorter one, as the tensioner is straight up&down, so there is clearly not enough pressure on it.

Out side of that extremely minor thing, I have had no electrical, steering, or cooling issues.

Also, if you have any plans on getting blown in the future (hehe) keep your old hardware. It will help you save a few $$$ when you have to re-install them...

 

[Forge]

Same here. I have the Steeda UDP's. The only issue I have is when it rains, my belt slips a little for the first 120 seconds the car is on. A shade longer if the AC is on right away. I am going to replace the belt with a 2" shorter one, as the tensioner is straight up&down, so there is clearly not enough pressure on it.

How many miles do you have on the stock belt? I never hear dof this issue. Is it possible you original belt is just getting old and stretching?

 

[marcspaz]

I have 20k on the car right now, but it has been doing it since I installed the kit a year ago. I only had 500 miles on the car when it went in.

Yes, I know...A whole year. LOL I am very laz...oh..ah..busy.

The belt is just too long for the smaller pullies. The center of the tensioner is 3" closer to the passangers side compared to when the stock pullies where on.

 

[Forge]

very strange, let us know when you ge tthe new belt if it helps.

 

[Silver06]

I just ordered Steeda UDP's. Have done alot or research and most people experience no problems w/ them. if you get 11 extra miles per tank for me that is like $3 per week of gas savings. At that rate the UDP's almost pay for themself in a little over a year.

I have read that Ford (and most manufacturers) over crank accessories anyway. In theory you are supposed to get better life out of the accessories as well by not spinning them quite as fast and as much (but who knows how much this really helps).

 

[SoundGuyDave]

Dave -
As you sure, when i talked to Steeda, they said the rotation speed of everything was slowed down a small amount. The waterpump pulley size is increased only so the stock belt will fit correctly. I am not sure about the water pump, you may be correct about that one spinning at the same RPM, but i was pretty sure they said it was slowed, but had no adverse effects on the cooling "steeda sales skills at work".

With that in mind, i drove my car in stop and go trafffic in 110 degree weather with over 80 percent humidity and i saw no cooling issues prior to the turbo install.

No, actually, you are correct... That was MAJOR brain-fade on my part. The pump is slowed down quite a bit with UDP's, HOWEVER, those of us with modded cars (particularly with taller gears) tend to run the engine in RPM ranges that the "little old lady from Pasedena" generally don't, and the extra engine revs make up for the intentionally up-geared pump speed from Ford.

Marc,

When you put the UDP on, did you also change the water pump pulley, or leave it stock? If you changed it, you should have installed a larger-diameter piece, that would even out the belt size. From your description, the pulley wasn't changed, which would effectively lengthen the belt. Change it out, it's not a big deal, even if you are laz... er, busy...

 

[marcspaz]

Yea, I replaced both pieces. Originally I did not want to install the kit because the box said it was for a 94 Cobra. I called Steeda and talked to Mike (sales manager) and he assured me they were the same parts.

They all fit ok and I like the .2 seconds I picked up, but I can't help but wonder if Mike wasn't completely straigh with me...LOL Oh well.

I am going to just replace it Friday. I talked to a buddy of mine who works at a dealer. He said 2" is too much to shorten it. He thinks I should go .5 or .75 less. I think the stock one is 27/32" (.84375) x 102" 6 rib so if I get a 101.25 (or in that neighborhood) I should be ok. I'll let you know Friday night what happens.

I still recommend NA cars getting them. It is a very nice compliment to the car...

 

[65sohc]

As another note, when you do the UDP setup, the crank pulley is smaller in diameter, but the water pump pulley is larger, which yields NO effective water pump impeller speed change. It will have no effect on cooling. The reason a lot of us have gone to the electric pump is for further reduction in parasitic losses. All the udp effectively does is slow down the speed of the AC compressor, alternator and PS pump, and not enough that you will notice a drag on the steering. You will notice a very slight increase in fuel mileage, as well. I picked up around 11 miles range per tank.

I don't think that is correct. Increasing the diameter of the water pump pully should slow it down just like on a bicycle. As you increase the diameter of the rear sprocket the speed of the driven wheel diminishes.

 

[GIG4FUN]

I don't think that is correct. Increasing the diameter of the water pump pully should slow it down just like on a bicycle. As you increase the diameter of the rear sprocket the speed of the driven wheel diminishes.

Welcome to S197Forums ! You got balls too. Thanks for correcting him. I wanted to but I was afraid.

Good job

 

[marcspaz]

OMG that is too funny!!!

 

[Charlie Sheen]

There was a caviat there:

"NO effective water pump impeller speed change"

Makes sense to me. However, the sky is blue in my world.