Moderators, I apologize, as this is a repost of a post I just left over in the Electronics forum...I'm not sure which forum is appropriate, as technically both are... I am planning to buy either the 140 amp or 200 amp Powermaster from Summit tomorrow. Because the 200 amp one is over twice as much ($360 vs. 160), I was wondering if anyone has the 200 amp one and can comment. I am leaning towards buying the 200 amp one because the car will have 2 Alpine PDX amps in it (1000x1 and 150x4), and I don't want ANY issues with lights blinking at night. I won't be cranking the crap out of it, but I will turn it up. I have a 140 amp OEM alternator in my '97 Z28, and with 1 Xtant amp, it blinks...hence my feeling I should move up to a 200 amp one for this car. Any help is appreciated!

need one then NO because I have used a 130amp in my Fiero to power a 1200 and 1800 watt 4ch amps and the lights didn't dim. Did you upgrade the wiring from your alt to your battery or hyper ground your engine? If you didn't then do so because it will make a huge difference but I am going to get a 200amp soon for my amps because my headlights dim with the stock 105 amp.

Well the 200$ diffrence is a lot. You might try a capacitor or a 2nd battery which can both be borrowed/bought for cheap before you make your decision.
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Also try revving your car when you have your lights on, heater or air on, windsheild wipers on, sterio booming to see if it helps any. An alternator will make more aperage at higher RPM's. If the problem goes away when you do this, its probably an alternator issue.

What is the part number for the 200 amp alternator from summit? Will it also work for the 89 Formula 350? I would upgrade wiring first and then see if more power is needed. As far as the cap and battery go, I would say the alternator is a better starting point. The way that I learned from my teachers is that a battery is like a credit card, you can borrow from it but at some point you will need to repay what you borrow. The battery will slowly lose power and how will you repay that power? DING! With a better alternator! Anyway, what is that part number again?

I have never had any luck with Powermaster alternators. My dad had one on a 5.0 GT and it surged badly. A very reputable local alternator service told me that a Powermaster is a very cheaply made alternator. I also asked about a GM 140 amp alternator. He said that he has never seen the 140 amp alternator actually put out 140 amps at any RPM. He said that something in it didn't have enough resistance?? He took my 105 amp alternator and rebuilt it with all the high amp stuff and it put out over 160 amps.

I had a little trouble with the alternator charging at idle. When you have a higher amp alternator, it charges more up top, but less at the bottom. I bought an $18 March overdrive alternator pulley from Summit and now at idle in gear with the fans on, lights on, and the stereo blasting the volt meter never moves. I also have a 1 Farad Cap also, but before the alternator, it would sit at about 12 volts max with all that on.

Total cost- $120 for the alternator rebuild with high amp parts and $18.88 for the pulley. That is the best $140 I have spent on the car yet IMO.

go with the smaller one, and get a capacitor if you have dimming problems.

Well, before having a chance to read a couple of these responses, I ended up purchasing the 200 amp Powermaster, to be on the safe side. This is a car that I will be keeping for a long time, so I want to do it once, and do it right. Its a helluva heavy, impressive-looking piece (I got mine in powerdercoated black). I thought it was nice that Powermaster even load tested it...127 amps at idle, 209 at 3,000 engine RPMs If this gives me more amps at idle than the stock one at peak, I dare say I am in good shape.

My Z28, with the stock 140 amp alternator and the massive Xtant, never blinked at a cruising speed, so I should be good with this one If Powermasters are supposedly made cheap, I'm shocked so far. Time will tell. Thanks for the feedback, everyone...

You went with the right choice getting the 200 amp alternator. All the power starts with the altenator a capacitor or even a battery will only help a small amount. Be sure to upgrade wires and you will be set and no harm will come to the car..

What he said. And don't forget to upgrade "the big three", which is just as important as the alt. itself.
Most people just do one and not the other which is why some say it didn't make much difference. Kinda like trying to breath through a straw while you're running, if that makes sense.
Here's a link to show how to do it properly.
http://www.the12volt.com/installbay/...TID~73496~PN~1

powermaster is certainly not a cheaply made alt... it is definitely one of the top quality manufacturers of alts..only other alt in the same league for mass produced companies is ohio gen, but those are even more pricey...


even with a 200A alt you will likely have dimming.. I have a 300A in my commuter car and still have dimming simply because an alt cannot respond fast enough to supply rapid bass notes.. this is where your battery really comes into play.. float charge that can maintain the needed voltage until the alt catches up
is important..

regardless, I would say you made the right choice and got a good price as well.

Did you upgrade the big three? If you did not that is likely the cause of your dimming. It could be something else like the regulator but if you are trying to shoot all that amperage through stock wiring then.... well good luck with that.

buy the one from summit and then buy a capacitor you should be good. i run a a rockford 4000 amp and 1000 amp i run 2 capacitors and the alt from summit and i'm good

good batteries are equally as importiant as the alternator. i would throw a pair of optima yellow tops in there and do the big three... with all of that you could practically run double of what you are now.