Once again, looks like the car is going to need yet another alternator. This has become much too frequent of a replacement for me and I'm looking for some alternatives especially considering the extra load on the electrical system that my FAST system + FastTrack harness have introduced since the 396 upgrade. I'm trying to get a feel for what others are using when they need more juice than the stocker can reliably produce.

Based on the forum search, it looks like I have the following options:

1) Upgrade to the CS144 from a 1996 Corvette and lose the bottom support brace (otherwise a plug and play).

2) High Output Unit from www.alternatorparts.com. (Unsure of how plug and play the install is).

3) PowerMaster unit (same as #2)

4) Corvette Clinic upgraded GM Delco unit (pricy, but supposed to be a direct fit).

5) Have a local shop rebuild mine.

Car is reading approx 13.5 on the volt meter during cruise after its warmed up and with more driving, 13.3 and 13.4 is not uncommon.

I'd like to hear from any folks who have upgraded their alternators. I'm not super crazy about losing that lower support with the CS144, but enough people have done it without problems for me to consider doing it on my car. Any other experiences with the other options would be greatly appreciated. Please include any installation gotchas that you encountered with the switch.

Thanks,

Ron

 

well, I have a chrome alternator and wanted to beef it up, I took it to an alternator/electrical shop and they removed the inside and replaced with brand new parts out of a 165 amp alternator, so I have plenty of juice there for when I need it, I am going to install a big stereo later and wanted to take no chances.

 

I wouldnt like to lose that lower support either, you'll end up destroying another without it, it'll crack without the support.

I'm looking for someone to make one for use with my TPiS headers, I'm almost sure the original wont work.

 

What doesn't work with your TPIS headers? I have TPIS headers on my car and have never had any clearance problems with the alternator as a result. Can you elaborate more on your issue.

Ron

 

Well, most people have issues with being able to use the rear support with headers, it usually doesnt fit since it hits the primaries, and I figured I would end up having that problem as well. I havent put them on yet, so don't know for sure.

 

Hmm.. Assuming that we're talking about the same rear support (the little black bar attaching at the low point on the alt), mine clears w/o issue. I don't recall ever having an issue with this even when the headers were installed in 2000. Maybe the design of the headers has changed since then. Not sure.

Ron

 

Perhaps its a Hooker-only problem then, God I hope so because I dont want to be cracking alternators.

 

I tried a 120 amp with no appreciable change (probably because output amperage at idle wasn't any better). I did find a half volt dropping at the ignition switch after comparing the battery feed to the gage readout. I cleaned up the switch with electrical contact cleaner and got the half volt back. If you're pre '90 and purposely running the aux fan with the a/c on, the system can't handle it. The 105 amp alternator simply can't keep up and the aux fan was never intended for anything other than extreme driving conditions with the a/c off. Here's GM's latest Bulletin about the alternator - as far as they're concerned, your charge is normal (and frankly I doubt your FAST system has anything to do with it):

Bulletin No.: 43-64-07A

Date: January, 1997

INFORMATION

Subject:
Low Voltage Reading or Dim Lights at Idle

Models:
1990-97 Passenger Cars and Trucks

This bulletin is being revised to add the 1996-97 model years and to update text. Please discard Corporate Bulletin Number 43-64-07 (Section 6 - Engine).

Any vehicle may have a low voltage reading (if equipped with gauges) or lights that dim, when electrical loads are heavy at idle, or under very slow driving conditions. This condition may be worse with owner added electrical accessories, or with a discharged battery. THIS CONDITION IS A NORMAL OPERATING CHARACTERISTIC OF THE VEHICLE, AND NO REPAIRS SHOULD BE ATTEMPTED UNLESS A PROVEN FAULT HAS BEEN FOUND.

At idle, vehicle electrical loads may exceed the low speed output of the generator, but the battery can make up for this shortfall from its reserve capacity for short periods. During normal driving conditions, the generator is designed to do two things: supply the necessary vehicle loads, and recharge the battery. Long periods of battery discharge due to high accessory loads at idle will cause the electrical system voltage to drop as the battery continues to deliver the electrical power. Increased generator temperatures from extended idling can also contribute to lower electrical system voltage. As temperatures rise, the voltage setpoint is reduced to avoid battery overcharge, and the generator's output capability is reduced due to increased electrical resistance.

Depending on the vehicle application, normal generator output at idle can be as low as 35% of the full rated output (see Figure 1). With enough electrical loads, it is easy to exceed the low speed generator output at idle. This is a NORMAL condition that the battery can compensate for during short periods. Items that affect the vehicle system voltage at idle are driving conditions, the number of electrical loads being used, add-on accessories, and extended idle times. Normal driving conditions will recharge the battery and restore the charging system to its normal state.

Some typical electrical loads are:

Load Amps

Rear window defogger 25

Headlamps (low) 15

Headlamps (high) 20

High blower 20

Windshield wipers 6

Ignition 6

Brake lights 5

Dimming lights at idle may be considered normal for two reasons. First, a vehicle with a low state-of-charge battery or under a discharge condition will have a normal low voltage condition. As vehicle speed changes, so will the output of the generator. As a vehicle slows, the output of the generator may not be sufficient to supply all demanded loads, so the vehicle system voltage will drop, and the lights will dim. Secondly, as high current loads (blower, rear defogger, headlamps, cooling fan, power seats or windows) are operated, the regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the generator output. This is done to avoid loading the engine severely, so that engine speed variations caused by the increase in generator output are not noticeable to the driver.

Component Functional Tests

Make sure all battery and ground connections throughout the engine compartment are secure and tightened. The battery and generator performance can be checked as follows:

Battery

1. Turn the ignition switch and all accessories "OFF."

2. The battery should have a "green eye" and the terminal voltage should be greater than 12.0 volts.

3. If not, the battery should be charged and tested following the instructions in Section 6D1 of the appropriate Service Manual before testing the generator.

Generator

The regulator lamp circuit provides the best diagnostic indicator for generator faults. Confirm that the lamp is operating properly, and isolate the unit with the Universal CS Generator Tester (J 41450-B).

1. WITH ALL ACCESSORIES OFF, run engine above 2500 RPM.

2. Diagnostic lamp should remain off. Voltage at the battery terminals should be between 14.0 and 16.0 volts when cold, and between 13.0 and 15.0 volts with engine at normal operating temperature.

3. Install a carbon pile tester (VAT-40 or equivalent equipment) across the battery and an inductive ammeter on the generator output wire(s).

4. Run the engine above 2500 RPM and load the charging system until peak output is reached.

5. If the peak measured current is within 70% of its rated output and the diagnostic lamp remains off, the generator is good.

If the generator does not perform to the above tests, refer to Section 6D3 of the appropriate Service Manual.

 

never has a rear support thingee before.. 8 years and no issues.. can someone snap a pic of what they are talking about? just curious to see what it actually looks like.

 

I happen to live 5 miles from the Corvette clinic...Chris Petris did all the work on my car till he went full time with Corvette Fever...he put the upgraded GM Delco unit (140 amp) on mine 2.5 years ago...never a problem since and I never see below 13.9 with everything turned on...14.3 with nothing turned on...if I recall correctly it was like $50 more than the stock replacement...

 

I too am looking into a higher amp stock-style alternator to swap mine out.. I was told that the one on the '85 vettes was a 120amp one, but at idle with the fan on, and ac on it does dip down into the 11.5v range..

 

I have seen this one before. My thinking behind the FAST being part of the voltage drop is the fact that not only is the FAST there, but the GM ECU and the FastTrack harness - all 3 of which are using 12v power. In addition to that, the FAST does not have dual stage fan control which likely means that both fans are activated in parallel at the defined temprature in the software. Cooling is definitely not an issue with the car, but the load of both of those fans vs the CS-130 may be the problem.

FAST also notes possible driveability issues when voltages dip below ~13.2 and it's been talked about on turbobuick.com several times as well. I'm not experiencing this issue, but could be on the cusp of this if I was to ignore the problem.

What really appears to get the car struggling is the rear defog (which usually gets turned on when its dark out so the headlights are on). I can see voltages in the 12.5 range which never used to happen before. The current alt is yet another CS-130 Delco installed just over a year ago. Battery was also installed at the same time. Upon load testing both devices (battery and alt) - neither one was particularly good and both showed signs of near-term failure.

In addition, the longer that the car is driven, the lower the voltages tend do go. When first started, voltmeter is reading 14.0-14.2 and 30 mins later, we're at 13.4-13.5 with no accessories running besides the fans.

After talking with both Powermaster and Alternatorparts.com, looks like the CS-144 installation via tech tip and a new battery will put the charging system back into tip-top shape for me.

Ron

 

It appeared that Chris' solution was a modified CS-130 and it was selling for $310 which was a lot higher than other options available such as alternatorparts.com and powermaster. Not sure if this is the unit that you got, but it appears to be the only one offered on his site for the 89.

Ron

 

Using Chrome Powermaster 144, install not an issue, did have to mod the lower Alt brace, cut and mod length to block, other than that, a breeze.

 

AC Delco 120 AMP sicne 1997!

 

I had a Powermaster direct replacement in my car for years - no more alternator problems. Direct fit - no mods. And it is chromed too!

 

can anyone post up part #s for a heavy duty alt. for my LT4 ?

 

Have you considered an smaller diameter pulley ? The type that usually comes with the underdrive crank pulleys. If installed alone it will keep the alternator spinning alot faster.

I installed one recently on my stock alternator (105 amp?) and now I always remain above 13.5 volts at idle, with all the loads (stereo, amps, aux fan, a/c blower and lights)

Can't say for sure what this will do for the longevity of the alternator, but a local shop rebuilds them (replaces bridge, regulator, and bearings) for less than $50, and the pulley only set me back $20, so it will be a while before I spend the $300 that one of the "Extrerme Duty" version's cost

Gary

 

I went with the Iceberg kit from www.alternatorparts.com. The finned rear case included is a very nice casting and the parts seem good. They sent the wrong size rear bearing with the kit. I went to a local rebuilder and he said the kits are good but they don't put out any more power at idle. I went with the 140 amp version and I haven't seen any higher voltage at idle. It works fime otherwise but it isn't the solution to low voltage at idle. Spinning it faster with a smaller pulley makes sense.

 

Probably not a bad idea in this case. I guess in general I have never been a fan of underdrive pulleys.

Ron