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Discussion Starter #1
Im getting a new sound system for my '79 Vette. The sound system will total 600watts. I have been hearing conflicting stories of whether or not it is necessary to upgrade to a high output alternator. I don't want to buy an alternator if it isn't necessary. What would you guys recommend?
 

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You shouldn't have any problems with your alternator with 600 watts. I've had a 600 watt amp in the car for years with the stock alternator.
 

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is 600 the RMS or max power rating? If max power.. no issues but would always consider a capacitor when upgrading.. especially if adding a sub woofer
 

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Discussion Starter #4
Im getting 2 amps from Polk Audio. One is the PA660 which has 300 watts RMS (75x4) at 4 ohms. The other amp is the PA880 Monoblock to power the subwoofer, which is 300 RMS (300x1) at 4 Ohms.
 

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http://forum.grumpysperformance.com/viewtopic.php?f=70&t=355

http://www.powerstream.com/Amps-Watts.htm

read thru this link
IM always amazed at the lack of research many guys do before purchasing components, who then are stunned and amazed to find that those components won,t work correctly without further upgrades to the electrical system, and can,t figure out why the battery drains .
example
you decide you need a 800 watt sound system and your installing it in your car when the tech suggests you might want to install a larger more powerful alternator.......IS he correct? do you need one?

Converting Watts to Amps

The conversion of Watts to Amps is governed by the equation Amps = Watts/Volts

For example 12 watts/12 volts = 1 amp

so 800 watts/12 volts =67 amps

now its a sure bet that the stock alternator that puts out about 90-110 amps (depends on year) and that the basic electrical system requires almost that current flow to function,without the additional equipment additions,will require an upgrade!
so yes! only an optimist would even think, for an instant that the stock alternator would keep up with the increased current draw, of that 800 amp sound system, the tech guys who are bound to suggest a larger alternator be installed are correct, you'll want to install a 200 amp alternator like the one linked to above in this thread
the high output alternator will require a larger gauge cable between the alternator power out and the battery positive terminal and adding an additional larger gauge ground to the engine/frame/battery negative sure won,t hurt
 

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Discussion Starter #7
So im going to upgrade the alternator to a 140amp one. I did research and this also involves upgrading the alternator wiring, or as they call it "the big 3." I saw instructions on how to do it, and it looks simple, but it was for a normal car with the battery mounted in the engine bay.
I have a 79 vette and the battery is behind the drivers seat. Has anyone here done a big three upgrade on their 79 vette?
 

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So im going to upgrade the alternator to a 140amp one. I did research and this also involves upgrading the alternator wiring, or as they call it "the big 3." I saw instructions on how to do it, and it looks simple, but it was for a normal car with the battery mounted in the engine bay.
I have a 79 vette and the battery is behind the drivers seat. Has anyone here done a big three upgrade on their 79 vette?

I am working on an upgrade to a 220 amp alt for a friends 81 vette.....

different alt completely, I will let you know how it works out, the wiring isnt bad, buy a roll of cable and add your own ends
 

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Do not skip the big 3. On my o6 with a digital gauge I can see the difference. This will help the charging system on any vehicle.
 
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