Just found out my alternator is bad and getting a new one. Will replacing the Stock Crank pulley prevent me from killing another alternator? I have 2x10" Type R's 1000watts total RMS subs and headlight dimming with the UDP.

97 max 100k miles with UDP & Red Top

 

UDP does barely nothing on our cars.

People say that the UDP will drain your battery quicker if you have subs. Which in turn I think will kill your alternator quicker I think....

 

For some reason the alternator doesn't get to put out as much amperage with the udp, I remember looking at a chart comparing the stock pulley to udp with alt amperage and it was way less than stock, so if you have a system it's one or the other. I would say if you track your car alot or autocross, keep the udp and ditch the system, or try to do the big 3 upgrade to help the dimming.

 

bump

so the UDP underpowered the system's amperage/voltage/both?

 

The diameter of the pulley causes the attached belt components to spin slower from what I've read so you get a lower alt output. Like at idle for example if it normally puts out 25 amps it's only putting out 20 amps with the udp, that's just an example, but I think at around 4000-5000 rpm it puts out around 125-135, with the udp it puts out around 115. And remember a stock alt is designed for stock stuff, so when you add a system you are already going above the engineer recs (even though most alts can still handle it) and then when you lower the output with an udp your just at a loss. I would do the big 3 and see what happens.

 

Skip the UDP and look in to having the alternator rebuilt to handle your system.

 

Just how much juice are those two tens pulling? I knowyou stated what they could handle at RMS but what are you pushing to them?
I ran a UDP with two Kicker Comp VR twelves for years with no issues. I had a 500 watt amp pushing them so it wasnt a major system but the car performed fine power wise with the UDP.
If your pulling some major juice then it might be wise to ditch the UDP.

 

I thought the 4th gens OEM alt put out 115 amps and the 5th gens put out 125?

 

The guy at autozone said stock alternator was 125.

They are 1000rms 3000max powered by 2 kenwood amps, I usually keep them turned all the way up.


I was looking into the components for it, how long of run do I need for alt to battery? What is the diameter of the post on the alternator to fit the eye ring that I'll be adding. 5/16" sound right?

 

So you have two 1000w amps pushing them? If so, I'd ditch the UDP.

 

using a udp is a contradiction to having a system. you don't want to under-drive the alternator if your pulling a larger than normal current. you can get a lightweight stock diameter pulley and doing the big 3 is always a good idea. just figure out how you're gonna run the wires and measure.