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Old 08-13-2019, 05:33 PM   #5
Hacksaw
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Default Re: Alternator question

Quote:
Originally Posted by bigfoot584 View Post
Engine rpm's ? or actual alternater rpm's ?


Big difference.
Just checked with an old guy who was a rebuilder and had a test bench. From memory he says about 1800 alt. rpm before they began to produce + current. So on a normal pkg. the ratio of crank to alt. pulley is approx. 3 to 1, which means at idle your not producing current back into the battery. Now with a smaller race crank and larger race alt. pulley to avoid spinning the alt. to the moon it's probably 1100 or 1200 rpm. Also they eat up at least 3 hp, maybe more.
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