Is My '87 GN Alternator Too Small?

[dennisL]

I recently discovered that the alternator on my 87 GN is a 96 amp unit rather than the 120 amp unit that was there before the Buick dealer replaced it.  This was done in 2001 but I just discovered it while cleaning the engine compartment.  It seems to be working fine but ...


Should I replace it with the proper 120A version?  Will the 96A alternator negatively affect performance in any way or am I ok as long as I don't install a mega-watt stereo?


I'm thinking that Buick used the 120A for a reason but I don't know what it was.


Oh, and my male ego would appreciate it if you would keep this quiet.  I don't want the general public to know that I have a tiny alternator.     Thank you.

[Steve Wood]

It might be on the smallish side at night with the defrosters, etc on and a high amp fuel pump.  I never had a problem with a 110 amp unit...

If your voltage holds at least mid thirteens under wide open throttle with the lights on, it is good to go.  Should be in the 13's at idle as well

If you ever replace it, look for the second generation CS144 as used on the 94-96 impalas and other big cars.  It puts out a lot more at idle and reaches 140 amp peak.  It is better made and costs about the same as the 120 amp original.

[dennisL]

That's what I suspected Steve, thanks.  The voltage hasn't dropped below 13.0 at idle, driving, or wot, according to Power Logger so I guess its ok.   I don't know how many amps my hot wired fuel pump draws at 18 psi of boost and since the alternator output probably goes down with rpm, I was concerned about that.


I feel better if you used a 100A for awhile and had no problems, but I'll start looking around for a replacement.

[Steve Wood]

bit down this page are graphs for 108, 120, and 140  http://www.vortexbuicks-etc.com/alternatorselection.htm

As long as the voltage is acceptable, you know the alternator is handling the load okay.

If you are reading the voltage on the logger, you can count on the voltage coming out of the alternator to be somewhat higher...

[SuperSix]

Oh, and my male ego would appreciate it if you would keep this quiet.  I don't want the general public to know that I have a tiny alternator.     Thank you.

 

[tb3]

sounds like you need a "power bastard" alternator 
 
is the cs144 a bolt-on plug and play?  utilizing all the factory alt brackets?

[dennisL]

is the cs144 a bolt-on plug and play?  utilizing all the factory alt brackets?

I was wondering the same thing so I did a little searching ...
found this, but not sure how much is applicable.
http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=493219

[Steve Wood]

yes it is

[Steve Wood]

the two video links at the top of this page explain the difference and why it is better made

http://www.vortexbuicks-etc.com/alternator.htm

[tb3]

thanks steve!