Alternator Upgrade

The stock alternator is perfectly capable of handling most of a C4 corvettes electrical needs. The problem is it is under a pretty large load at idle with all the various items pulling on it. From the electric fans, a/c, stereo, headlights, etc. Not to mention the under hood temperatures are pretty hard on it too. The stock CS-130 alternator fails pretty often and you will learn quickly all those lifetime warranty deals you have enjoyed on other vehicles don’t apply to a vette’s alternator.


The solution is actually pretty easy. You don’t need a specialty alternator from some online store. What you need is a CS-144 from a newer model gm car. I took the one off my 1997 Pontiac Firebird with a LT1 motor in it since I needed to get the job done fast and just ordered a new alternator for the firebird.

The CS-144 puts out 120 to 140 amps depending on the model. The stock CS-130 puts out 105 amps. But where the CS-144 shines the most is idle charge rate.

CS-130 = 60 to 70 amps at idle.

CS-144 = 90 to 95 amps at idle.

THIS is why it does so well in the C4 corvettes. This still has to be one of the best upgrades I’ve done to the car honestly.

Here is what a CS-130 (stock alternator) looks like beside a CS-144.



Well onto the install 🙂

The CS-130 (stock alternator) has a 16mm flange and the CS-144 has a 20mm flange.

You need to grind off 4mm (.16 inches) from the upper (small end) flange mount which looks like this :


I chose to change the pulley out to the one from the old factory CS-130 alternator to keep the speed and belt placement the same. I have run across other articles where they didn’t change the pulley and claimed it made the alternator spin slower at idle making it run cooler. I personally think that turning slower at idle is actually bad for the alternator thus making it work much harder at idle. Here is how it looked with the pulley changed out on mine.



Otherwise its a straight bolt up and plug and play electrically. But there is one last step that you need to do which is complicated. The rear brace that runs from the back of the alternator will not line up with the newer one. This brace must be replaced with something or the front frame the alternator mounts to will crack and fail eventually. If you are handy at metal working you can make one yourself. I have a customer of mine that is planning on creating a custom brace he will offer to the public soon. When I get one from him I’ll post pictures, price and a link to buying it.

This is what the old brace looks like with the new CS-144 alternator installed. You can see there is no place to bolt it to the new one.



I’ve had no issues at all since the change and for the first time ever it charges at full voltage at idle. Something the old alternator never could do.


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