Have a 91 Z28 and pretty sure the alternator is on it's way out, again. I think this be the second or third one. I'm sure the underdrive crank pulley isn't helping matters since apparently the CS130 doesn't have very good cooling to begin with.

Anyway...I've been going through various threads on forums but still haven't found what seems to be a concise answer to whether or not there is direct bolt-in better replacement (not worried about an adapter harness, just not too interested in cutting/grinding, welding, scouring boneyards for obscure brackets, etc.).

Can anyone help with a clear summary of what I could drop in with essentially no mods other than maybe a wiring adapter, instead of another CS130?

 

I have a March under drive pulley system and after fighting charging issues I wanted to just go back to the original crank pulley but it appears my son scrapped my original. I do like the look of the aluminum March kit so I decided to replace just the Alternator pulley with one from Summit that was much smaller 1.63" dia. to overdrive and spin the alternator higher. It seems these alternators require about 1800 shaft speed to charge at idle. You could look at http://www.powermasterperformance.co...r_Catalog/1014 to get up to a 200 amp unit but I would ditch the under drive alt pulley first as that may make you happier and take less from your wallet. The math for the pulley ratio is crank pulley size/alt pulley size X crank shaft rpm. The redline for these alternators is about 18,000 shaft rpm. So in my case 5 / 1.63 = 3.07 X 650 = 1995 alt RPM at engine idle. My original was 5 / 2.625 = 1.90 X 650 = 1238 alt RPM way too low.

 

Yeah... been considering if I should just put the big crank pulley back on anyway. Not like I race it or anything. That would entail the cost of a new belt, assuming the alternator isn't shot but I think it is, or at least close. Seems not bad for a while, charging up around 14V, but according to the volt gauge once things start to warm up the voltage drops off and has a hard time even getting to 13V mark.

 

Take it to the parts store or an alternator shop and get it tested, that will tell a lot. The factory crank pulley would be your best bet. Also if you want power this is the worst place to look, there are so many other less troublesome mods. that do not have such a detrimental effect on the overall package and provide more bang for the buck.

 

put the stock pulleys back on the car... you won't miss the 3 or so HP you will be giving up, but your engine will appreciate the extra coolant flow and your alternator will give out much needed electrons.

 

plenty of documentation about undercharging of batteries with under drive pulleys

If you did actually need a Alt upgrade ; the larger CS 144 is a popular swap
http://alternatorparts.com/cs130d_cs...uv_upgrade.htm

 

I don't have problems with the battery being consistently dead/weak, per se. Even with the charging irregularity it has again, it still always starts and thats even considering I dont drive it much. The battery in it now is 5 years old and load tests OK and tests OK with one of those conductance testers. I think the problem is that the crappy airflow of the CS-130 coupled with the underdrive pully eventually damages the regulator.

If you look at the alternators newer than the CS-130 they are generally much more open. Pack that much power capability in a small package and they need lots of cooling. The newer alternators fix that and provide stronger output at lower RPM to boot.

That said, the stock pulley may be the better alternative. Guess it mainly depends on how much diddling I want to do. Usually that's not too much these days.