gm style alternator on my 1600?

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gm style alternator on my 1600?

Post by digger » Tue Aug 26, 2014 10:59 pm

i've seen pics of guys mounting gm style alternators on a vw engine before but not sure how they mounted them.anybody know of a bracket or kit to do this would be helpful.i can fabricate brackets if needed just not sure what they need to look like.i plan on retaining the stock alternatorbut gutting it out to just run the motor already has the double pulley on the crank from the ac compressor that is no longer there.

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Re: gm style alternator on my 1600?

Post by Marc » Sat Sep 06, 2014 11:12 pm

One issue you'll need to deal with is the pulley ratio - the A/C pulley's pretty small so using it will result in a low alternator speed. "Overdrive" pulleys are available (~$20), a small 2.3" one might give you enough alternator RPM to realize a benefit from the higher-output alternator. High-capacity alternators take more power to drive than a single narrow V-belt can transmit, which is why dual-sheave V-drives and eventually multi-groove serpentine belts were adopted.
Running both the fan and an added alternator with the same belt is also problematic; without an idler pulley you can't get more than a 120° contact arc on one without sacrificing some on the other, and the smaller the contact arc the less power will be transmitted without slippage.
Bottom line is that it would be better to use a larger secondary pulley instead of that little A/C pulley, and if you're going to go to the trouble to graft one on you may as well make it a multi-groove with a spring-loaded idler pulley on the "slack" side.

Last bumped by digger on Sat Sep 06, 2014 11:12 pm.

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