I have an ASP U/D pulley and recently I upgraded my amp and subwoofer - now I'm afraid to turn up the bass, my headlights are dimming big time and my volts are going real low.

My question is - can I upgrade my alternator to handle the power without having to go back tot he stock pulley? Will it cancel out the gains I got the ASP for in the first place?

 

Well, if I'm understanding your question correctly, why don't you just get an overdrive pulley for your alternator to compensate for the fact that your crank is underdriven? With the alt O/D pulley and crank U/D combination, the rotational speed the alternator is driven is probably within 1% of stock for the same engine RPM. Now if you've already got the O/D pulley for your alternator and you are still having problems, you might want to look into making a change.

Forgive me if you already are well-stereo versed, but I saw huge differences in the way my headlights dimmed and my operating voltage was held much more constant with a 1-farad capacitor in the back of my car near my amps. The capacitor will charge from your alternator at a much more steady rate and store charge and disburse it to the amps as needed rather than sending a voltage waveform filled with sharp spikes through your cable feeding your system (and making your headlights bump to the music).

I have a ASP pulley and I got the O/D alt pulley setup (an extra $23). I use 0-gauge copper to go to my cap and I am powering a Rockford 800a2 power amp (it's old, a 1999 model) which speced out at 925 watts from the factory at 2-ohms. It's seeing a 3-ohm load from both speakers which puts it somewhere around 580-585watts RMS (rockford amps' regulation systems tend to stay pretty close to logarithmic with respect to load). I'm also powering 4-ohm front/rears at 50+ watts RMS a pop from my punch 400a4, putting my system somewhere close to 800W, probably around a 60-amp current draw.

I haven't had problems with my setup, before and after the pulley, and I run around with my stereo blasting all the time, but I don't know what exactly you have. (I have had problems before running it for very extended periods of time, like 4 hours or more, loud at only idle at outside parties, but taking the engine up to 2000 for a couple minutes fixes it) If you don't already have a capacitor near your amps, I would try one out to see if it makes a difference. Upgrading your alternator sure sounds drastic, but you could very well need it; I don't know the kind of power you are pushing through your system. And yes, your premise is exactly right, if you drop in an alternator that puts more amperage into your system, unless it is somehow more of an efficient mechanical to electrical energy generator than your old one, you will lose HP due to your engine powering your bigger alt rather than putting the power to the wheels.

I have seen people on here and other boards say the horsepower loss is minimal, maybe 2 or 3 from doing the overdrive setup on your alternator when you do your crank pulley, so in effect it will cancel out at least some of your gains from your ASP. But if it fixes your problem, it's probably worth it. So if it were me, and I didn't have either a O/D pulley or a capacitor, I would get either one of those before I changed out my alternator. Also for the record, make sure your power wire feeding your amps is large enough gauge for your system. If not, you can lose power through the wire due to it acting like a small resistor under high current loads (making you turn up your stereo more to compensate and drawing more power from your electrical system).

Hopefully you get your problem squared away, whether my advice helps or not.

 

(first post: everybody laugh at the newb!!!)

 

hey dude thanks a lot for the response, I have heard from a few folks now that a cap is my first step, I'm going to try that.

I don't have a crazy system, and maybe the gains are turned up too high on my amp, (Kenwood KA7252 1000W going to one RF 10" sub) but at idle my volts twitch to the beat between 12-13. If I jack it up a little, the volts are just touching the redzone. I makes me nervous, not knowing too much about what the effects could be on my alternator/battery. Am I being too worrisome or is this going to f#ck me up?

 

Iv got a 3.0 farad Cap (Pheonix Gold) that i could sell you for like a 100 or so + shipping, was used sparingly. Lemme know if your interested.

 

mako22,

Well the effects of the sub on your vehicles' system can't really be "good" per se. You tend to go through batteries and alternators faster than you would without a system, and that's just the plain truth about it. Your car's alternator was not designed to support a big system, but that said it is capable of doing it; it's just like anything else where it will fail quicker from wear and tear.

100 bucks is a great price on the cap, I would look into getting that or something similar. I wish I could have found a 3F cap for $100 instead of buying a 1F for $80 new a few years ago.

But you never mentioned whether or not you have the overdrive alt pulley. Being an A4 guy, you should probably already have one to begin with, but if you're pushing power to your subs, and don't currently have one, $23 + shipping is definitely a great investment on top of your cap, even with its intrinsic 2-3 HP loss. The cap will smooth out the amperage being sent to the subs, and hold your voltage levels steady, but it will be still the same net energy going to the subs. The cap isn't going to conjuer (sp?) energy up from nowhere. So if you are running in a deficit, get your alternator spinning the speed its supposed to, and if that is already been done, then maybe your suggestion of getting a bigger one wasn't a bad idea.

Good luck

 

Its in my 86 MCSS. Ill be home april 29th. If you can wait that long, or i can ask my dad to take it out and package it up if your really interested. It worked great for me when i used it.

 

Personally, I don't like the idea of having to put on an alt pulley. So you are going to gain 7 rwhp with the asp pulley, and then subtract 3 rwhp with the alt pulley. Sounds like alot of time and money for 4 rwhp.

 

Better then 0 RWHP and pushing ur car around town.