What is the down side of replacing the stock 105 Amp alternator on an '86 L98 with a 180 Amp unit? Any input would be greatly appreciated.

 

To be safe, use a larger charging wire. Otherwise, I don't see any downside.

 

The only downside would be if you buy a cheaply made 180AMP alternater that cannot dissipate the heat. The corvette fans will pull the heat away from the radiator, but unfortunately the alternator is right in the path of the hot air from the fan. If the alternator can't handle the heat, it'll burn up very quickly. Make sure the alternator is built tough.

-Tim


[Modified by Hawaii89vette, 12:27 PM 12/14/2001]

 

The ONLY down side is you won't get to enjoy changing out alternators on your Vette again.
The stock 105 Amp Alternator just can't cut it. It can stand the load but it can't withstand the load AND the heat encountered under the C4 hood in the summertime.

The 120 amp ZR1 unit is the one I use.
Where the heck did you find a 180 amp alternator?
Does it have a internal voltage regulator? It WILL need to have the internal regulator,else wiring changes will be necessary. Not for current considerations but because you'll have to install an external regulator.

If it's the internal reg. type the following applies:

No wiring changes need to be made.
As far as heat dissipation is concerned, a unit capable of putting out 180 amps is such more heavy duty than the factory installed alternator that you won't have to worry about heat.
You'll have over a 100% design overload factor with the 180 amp unit.
The factory 105 amp has about a 50% overload factor.
THis means the factory figured the max load on a C4 would be around 70 amps.

70 amps + 50% = 70 + 35 = 105 Amps.....The Stock Alternator.

If the bearings are of good quality you'll wear out your Vette before this alternator goes out.
Again, the stock wiring will work fine, no changes necessary.

Good luck with it.

 

VetNutJim,

The 180 Amp unit is a rebuilt unit which is rewound to 180 Amps and it does have an internal regulator. Its a direct plug-in replacement for the stock 105 Amp. I was concerned that the higher output would either fry the factory wiring or somehow screw up the ECM. Thanks for your most helpful response.

 

Unless you have added a lot of high current electrical devices, I don't think you have anything to worry about. The regulator keeps the same output voltage no matter what the current capacity is for the alternator. The red wire (output) on the alternator will not need to be made larger unless you have added equipment that will use greater than the 105 amps the OEM alternator put out.

 

CG77VETTE,

Glad to be of help. I've had to change out alternators on both my Vettes.
The hot summers here in Georgia claimed them both.
Was able to get the 120 amp ZR1 alternators form a discount autoparts house here. They are just big enough to be able to supply the C4 load ADN take the 90-100 degree summer heat.

The actual load on the alternator won't be any greater than it was with your stock unit so your wiring/starter/ECM will be just fine.
But the greater "possible" amperage capacity means the big alternator will be just loafing along supplying the load whereas the stock unit was a lot closer to it's maximum capacity.
I wish I could have found one like that (180 amp) when I changed mine.

Again, glad I could help. That's what makes this forum such a great place for us Vette owners. There are a LOT of very knowledgeble folks here.

 

Here is some advice I received from a local rebuild house. The stock housing is undersized for the amperage (and wattage) it is producing as it is. If you add capacity (and use that capacity) it will fail sooner. The problem with the CS-130 (if that is what you have - sorry forgot to check year) is that it is marginal to dissapate heat, and in a C4 it is in a hot envoirnment - so double problem for that design.

If you need that kind of capacity (and BTW find out what it produces below 1200 RPM, you may be suprized) then you need an entirely different case to handle the heat it will produce.

If you are looking for a dependable alternator in standard ratings, I would suggest not buying a parts house rebuild. Have your's rebuilt locally or look into an iceburg kit rebuild.

Pete

 

I'm looking at doing this as well. Is the 120A alternator plug and play or do you need to change plugs. What should this cost for the upgrade and will they accept the 105A for a core?

 

This site has been posted before as a source for upgraded alternators: http://www.alternatorparts.com.

 

I'll say this again, but know you guys will not listen.

A higher amp alternator will not necessarly last longer, especially if it is using the same CS-130 case. If you really need more capacity, you need to find a better method to get rid of the heat.

Why do you want a higher output alternator? Huge stereo? Mag-lift levitation?

If you are trying to get the alternator to last longer on a stock setup:

1.) stop buying junk rebuilds from the parts store.
2.) have your failed alternator rebuilt from a local shop - use one that's been around forever.
3.) look into the iceburg kit on the link above. That guy will sell you a brand new (not rebuilt) alternator for the price of a junk parts store rebuild and no core charge. Call him (that's the Michigan guy?).
4.) keep your battery terminals perfectly clean and tight and don't use abrasive items like a wire brush or sandpaper that will remove the plating from the connectors.
5.) don't let your battery get low, keep a charger on it or battery tender. Use the correct device (tender or charger). Low batteries kill these alternators.

Pete