JC Whitney on line 15NV0663Y :12 SI, GM 100 amp alternator
price at about $119.95
Local price is $80 to $120
The Alt. used on the 84/85 is a 12SI. SI stands for
Systems Integral. The was the first GM alt that was
internally regulated. It debuted in 1972.
(That was a 10SI) Of course, GM was the first to come up
with an internally regulated system. This system was an
excellent system. It is so easy to work with and is a
good design. Well, in the 1980s with all of the computer
controlled cars coming out, GM needed an alternator that
could communicate with the ECM. In 1986 the CS series
Alternators came about. CS stands for Charging Systems.
The models, CS121, CS130, CS144 and now CS130D
(this is another story!
The number after the CS is the
diameter of the stator in Millimeters. So, on the 86/87
TR it's 144 Millimeters wide. Most all of the CS series
unit put out over 85 amps. The TR Alt. doesn't
communicate with the ECM. Instead, the regulator
monitors everything. It counts the AC counts so it knows
how fast the alt is spinning. and can even cut the
charge back if necessary. There are over 8 different
regulators used in the CS series. They all look and plug
in the same but they are different internally. I could
go on about what each regulator does differently but
that's another time
Upgraded 88 Sam with 100Amp plus Alternator Delco 12SI
used bracket from Rocky Road.
Used local Auto electric shop as alternator source this
is not a stock part buy local save time and money fitted
three alternators before found one needed part number on
unit is useless which sounds about right for a car manufac.