[cornflakes]

I heard someone say that with UDP the AC at idle might not be as good. Is this true? Has anyone had AC issues after they installed udp (crank and water pump pulley)?

Is this a trade off one has to consider before buying and installing udp?

[Mike]

Yes it does , where do you think that "extra" power comes from ? just drives things to a lower speed , it can be especially bad for things like your alternator as well, for the 10 or 15 hp i would look into other mods , ppl still do this one , cause its easy and cheap though

so its all up to you .... i personally dont have a UDP , since all the accessories in my engine are designed to spin at a certain speed , i really dont feel like underdriving them to gain more power to the wheels.

If you really want the 10 - 15 hp gain in your car , take out 100 - 150 lbs , its free to do that and lighter always wins, over brakes, engine etc

[habmann]

Personally i've thought about UDP's many times, but with running a system in my car, i'm not all that excited about under driving the alternator which is already under some strain. For a car that doesn't have an aftermarket stereo i don't think i'd be as concerned. Its really just a matter of what you want out of your car and what you're comfortable with doing to it.

[laidman]

I never had a problem with my system when runnign the water and crank underdrive pullies. I thought it was worth it, even though the car didn't cool off with the ac as fast. I had the windows down most of the time anywasy.

[cornflakes]

hmm...it's good thing to know this. I'm not an expert with cars by any stretch of the imagination but it sounds like UDP is bad for the alternator and that doesn't sound good.

I thought the UDP installation was purely an improvement overall of everything (if even it is only the slightest improvements). But I wasn't aware there were draw backs to it.

So it seems that there is good reason why "stock" is "stock" and not just because car companies want money for the cheap things they put in stock....

maybe im overreacting, maybe UDP's aren't as hard on the car for the sake of an ounce of more power. More feedback and results would be good to hear about UDP and if anyone has had issues with alternators (or premature wearing, failure, and replacement of parts due to aftermarket parts in name of adding some more hp).

I'm really not into HP gains.....if I was, i wouldn't have a focus. I'm more interested in simply overall improvement and efficiency of what I have (not trading one gain for another loss)....so to me, gaining more hp but sacrificing efficiency and the life/health of the car and its parts is not an overal improvement or gain. It's just short time fun but long-term car troubles.

Now it makes me wonder, are there really any mods that actually don't have any drawbacks to the overall well-being and life of the car (other than $$)? Which mods are a "win-win" situation.

[NOS2Go4Me]

Like I said in your other post, the addition of a UDP reduces parasitic drag on the motor. It "frees up" horsepower that was already there to begin with.

The "downside" is that the RPMs at which your accessories begin to operate at optimum levels increase somewhat. For example, my alternator doesn't fully charge below 1200 RPMs or so, but the low voltage light never comes on. I've tested available voltage with a multimeter and with the digital readout (less scientific, I know) on my DC/AC inverter... it never goes below 11.2 volts.

The A/C runs a little less "optimally" at idle than a stock vehicle, but on the highway your performance will / should improve a fair amount over stock. I noticed I could pull up hills with the lockup engaged in 4th where I had to get out of lockup before.

The only other thing that happens (that I've noticed / others have noticed) besides greater steering effort at low speed is that the idle air voltage is a tad low and that throws off the idle a bit. It's not "lumpy" or unstable, it just wavers a bit when the car is cold. It's still more than driveable, however. :)

If you have any other questions, ask away or shoot me a PM if you want. :)