Alternator Pulley size

[2 Fast 4 U]

What is better to use on an alternator a small or a big pulley??

[jordan]

It depends on how fast the engine is commonly spinning. If it usually at a high rpm a larger pulley may be necessary as this will reduce alternator rpm and at higher engine rpm this may be advantagous because you aren't overspinning the alternator nor are you creating as much drag. Though running at normal rpms the stock pulley size should be fine.

[sawdust]

Big pulley = altenator spins slower
Small pulley = altenator spins faster good at idle

mtcw.

[RallyBob]

Yup, on an alternator keep the pulley small for a street car. It has to spin faster than the crank to energize the field and produce any amperage. On a racing engine I use a larger 4" alternator pulley since the engine never sees low rpms.

Bob

[wrench459]

Open circuit voltage of a fully charged battery is 12.6 volts.
You'll need a half volt over to charge the battery.
How you make it happen is up to you and your application.

[2 Fast 4 U]

thanks guys, I'll be putting the small pulley on!!!!