Important: Improvements on Saturn Alternator Swap

[curt-s]

Looks like I will be trying a new alt sooner rather than later.. a few blips in voltage is now turning into long sprints of alt not putting out anything at all.
Also entirely possibly the bearings are going in it too, as i loosened the belt a bit and it made such a screech after. Not belt squeel, but internal dear god everything is exploding.
Maybe its just the entire car saying it wants to sleep permanently..


isnt that a newer alt a CS121D (*edit) with an oval plug? i assume you pulled everything at the same time from the wrecker.. trying to find a source for the oval plug since i have the earlier rectangular. maybe a blazer, would have to check the wmyards


*edit

Did some spec checking, not sure if this would contribute to issues while running through mounting wobble or throwing a belt. Definitely a pulley diameter difference, which would make it spin faster at all RPMs.

Mitsu:
Pulley Outside Diameter 65.0 mm
DE to Pulley 1st Groove 22.0 MM
DE to Rotor Shaft End 42.0 MM
Inside Distance Between Mounting Feet 78.0 MM
Split Mounting Foot Overall Outside Spacing 104 mm

ACDelco 335-1036 CS130 (pre-00 DOHC 1.9L):
Pulley Outside Diameter 63.0 MM
DE to Pulley 1st Groove 22.0 MM
DE to Rotor Shaft End 40.0 mm
Inside Distance Between Mounting Feet 79.0 MM
Split Mounting Foot Overall Outside Spacing 104.2 MM

ACDelco 335-1002 CS121D (00+):
Pulley Outside Diameter 61.0 MM
DE to Pulley 1st Groove 21.0 mm
DE to Rotor Shaft End 36.0 MM
Inside Distance Between Mounting Feet 81.0 MM
Split Mounting Foot Overall Outside Spacing 112 mm

 

[calgst95]

Just an FYI for those trying to figure out the tensioner bracket situation. If you don’t already know, Morrison Fabrication has an adapter bracket for this. It’s also a good time to support his family with some income since his recent loss. RIP Mr. Curt.

 

[william]

My second Saturn alternator stopped charging.
Determined the diode trio had failed again when surpassing 21000 RPM (8k engine RPM).
Replaced the pulley with a 2.75" pulley so it won't exceed 1740 @8000 engine rev.
Also added a custom heat shield between the down pipe and alternator due to prior early alternator death from excessive heat.

A few things to consider if you are going the Saturn route and have a high performing engine.

 

[DSM98GSX]

I put some good info on a turnbuckle setup at post #416 on page 17 also if you need a different alternative.

 

[george louis]

Estaría genial que pudieses como dice un diagrama de instalación de Saturno más q nada en las conecciones del alternador y las medidas del cableado y

It would be great if you could as a Saturn installation diagram says more than anything on the alternator connections and wiring measurements and

hey no worries bud, im in no hurry so i don't expect you to be either

I've got a lot on my plate right now and in about a week i'm looking forward to my first 2 day spell off work in over 2 months, I can't wait!!! (bad thing is i'm the boss and i still can't get a day off : )

I'd lik to run off a dozen or so of these pulleys to see how they do but the 6061 AL has me a little scared.. IT's plenty strong but i do worry about any shearing of the woddruff key or it starting to "wobble out" and have the hole enlarge over extended use.. THese are just things knoch and I wil have to keep eyes on for a while i guess

The wire on the bolt is the charging wire that goes to the battery.

The sense wire was the main topic of this thread and was mentioned and explained in the first few posts.

The brown & brwn/wht wires should be labeled on the connector itself. I have the same one with brown wires and the plug has an "L" "F" & "S". The "S" doesn't have a wire and you have to put one in there. I just took apart another harness I had laying around and found one to fit in there.

La f del alternador Saturno va al cable l del arnés del carro? Que es la luz de piloto? Y el otro va solo a un positivo de referencia? Lo q no entiendo bien es eso de q conectan un cable de la bomba o de algún consumidor q baje el voltaje para así el alternador pueda elevar el voltaje

Does the f from the Saturn alternator go to the wire l of the car harness? What is the pilot light? And the other goes only to a positive reference? What I do not understand well is that they connect a cable from the pump or from some consumer that lowers the voltage so that the alternator can raise the voltage

Se te agradecería mucho si pudieses aser un diagrama y compartir todo lo q se tiene que hacer y compartirlo

I would be very grateful if you could make a diagram and share everything that has to be done and share it

Desenganche el cable "F" que está causando su zumbido... todo lo que realmente necesita es el cable "L" (pero debe tener una luz ficticia conectada o freirá el regulador en el alternador)

La "L" y la "F" hacen lo mismo y activan la unidad (o excitan en términos de alternador), el cable "S" es para mejorar la carga y la estabilidad del voltaje.

He estado tan ocupado con el trabajo que no he tenido tiempo de conectarme a la red últimamente, así que lo siento por todas las respuestas alternativas a los PM y demás.

knochgoon.... I'll have them pulleys by mid october.. I got a broch of the correct size and have everything else i just have to finish up this huge paint job on a mansion that one of my builders lives in (hoping this wednesday..raining today and can'twork) so i'll be hitting you up soon for the trial run pulley for you.

i'll try and draw up a diagram here soon as well for the wiring since i've gotten a lot of requests over PM, email and here in the post.

as for adding a third wire to the plug... just go to autozone/o'reillys and ask for apigtail for a GM CS style alternator...they will say they don't have it if you ask for one for a saturn... man some parts people are just a bit tooun-informed to work at a parts store, but hey everyone starts some where

Me puedes compartir el enlace de la polea porfavor o el alternador ya con la polea para solo aser la compra

Can you share the link of the pulley please or the alternator already with the pulley just to make the purchase

Well I just placed my order for the smaller pulley 160 amp. Thank you for providing the link. I am wondering though. Have you not installed this on your ride yet? I guess Ill let ya know how it works if not. Thanks again.

I ordered the 200 amp version of it with the self exciting regulator from here.
http://www.motorcityreman.com/91scse1.html

Pero ese es de 105 amperes y la polea no creo q sea menos de 2" q dices q funcionaria mejor

But that is 105 amps and I don't think the pulley is less than 2" that you say would work better

Yea, the stock wires will work, but they are sure to be corroded from years of use as well as being a little small, which both of these things will hamper the charging efficiency a little, nothing major really, but most of us change them out for 4 guage just because we're alreayd there working on the system and want to have everything upgraded to the best possible parts we have access to

Glen se tiene q pedir el alternador Saturno de 105 amperios o el que dice eclipse autoexitante estoi en duda y la polea más chika no veo una opción de poder pedirla o el alternador de Saturno de 105 amperios ya viene con esa polea más chika que la que es de del eclipse modificado autoexitante

Glen has to order the 105-amp Saturn alternator or the one that says self-exciting eclipse, I'm in doubt and the coolest pulley I don't see an option to order it or the 105-amp Saturn alternator already comes with that coolest pulley than the one is from the self-exciting modified eclipse

Tengo el de 160 amperios con la polea más pequeña y es genial.

Dónde compro esa polea y de cuántas pulgadas es de 2"?? O menos?

Where do I buy that pulley and how many inches is it 2"? Or less?

 

[Phildoemb]

I didn't know where to put this just yet so i started here since it is a bit custom. The Original article can be found HERE

UPDATE/EDIT: YOu can getthe plug at any advance or oreilly auto parts.. you have to ask for a 'GM "CS alternator pigtail... they won't find it looking up "saturn"

above is the method I used to swap mine. There was however a problem with the wiring in this and every other write up on tuners and talk forums.

All existing how-to's say that the black yellow wire on the mitsu harness goes to pin "L" this is true as this is one way that the alt turns on and becomes active, but this circuit MUST HAVE AT LEAST 35Ohms resistance and up to 350 max. (which it does) and this wire alone is enough to work the alt besides the main power feed wire for charging.

However here's where things get off track.. The articles say to hook a switched 12 volt to "pin F" ...This is not really wrong but doesn't do anything! IT is ONLY another way to start the alternator should you not have a "battery lamp" wire that has the 12v with 35Ohm resistance to it.... The "F" terminal is for field and it has it's own resistance built in internally so i've read, but either way it doesn't need a resistor or buib and it starts the alt charging just like the black/yellow battery light wire does..

Now the alt will work OK with it wired this way but after scruitinizing the voltage at all times both on a data logger and FLUKE voltmeter since i did the install i can only say i was less than pleased with the output...sure it was better than OEM but nothingn to write home about. So i set about reading for probably 6 hours in 2 days and calling some of the top high output alt guys listed on the web. That's where i learned about "F"

The important wire is "S" this is the wire that reads the voltage at what ever given area it's attatched to and either lets the alt shut down a little or makes it work harder. And sure it will work withtout it but just not up to my standards or anyone like me ...Most people say loop "S" back to the +batt terminal on the alternator, but the problem with that is it's always going to read 14volts and not adjust at all.... The issue withour cars is voltage drop in the rest of the system and as we all know poor grounding.

Tonight after learning all of this i tore into alternator wiring and just finished with awesome reasults... Here's what i did ... I left the "L" wire hooked up... Pulled the fuse on my "F" wire line just in case i wanted to put it back some day and it was nicely tucked... Then i took "S" and soldered a length of 12 gauge wire to it and routed it back across the car and tied it into my distribution block where it could sense the "dropped volts" and also see how low the main system was getting under load. Then i took a length of 8 gauge wire and mounted 2 ring terminals on the ends.. One end got bolted to the hole in the back of the alt (obviously there for a ground IMO) and then hooked the other end to the main ground from the battery that hooks up at the trans.

I snugged everything up and started the car.. I took a voltage reading at the battery ..14.7 volts..NICE! Then i turned on EVERY accessory the car has..lights, A/C radio, rear defog, wipers, and hazards... And not a single flinch from any thing (normally i can tell low volts because my tach adapter makes my tach go nuts when the volts drop too low) I went back and checked the voltage again at the battery and it was 14.5 I could not have been happier and this was at IDLE..normally to get it back up the old wiring way i had to rev the car and it still would not make 14volts... Now it does it at it's low chugging with the AC on idle

HOpe some of you with saturn alt swaps check what i'm saying and log your volts or check with everything on... if they're fine, cool... If not you now know how to make it right !!

Do u have a wiring diagram that u might have drawn up so I can see visually what u did and where the wires are going.

 

[mjm0157]

Jayracing made this nice write up

You must be logged in to view this image or video.

 

[Bmonaco1]

Bumping this thread, as I'm still a bit confused...

For those running a "1-wire" set up, is this really as easy as just hooking up the positive post wire to the battery and that's it? Then, just tuck factory harness? If the harness is not being used, the ECU is ok with that? Thanks for any help!

 

[MindBlowin03]

That's what I use in my 2G and have no issues. 14.3+ volts at all times.

 

[Bmonaco1]

Thanks for the reply. Did you also replace the positive wire going to the battery to a thicker gauge? I was hoping the stock wire would be enough for an even easier install...

 

[MindBlowin03]

I did. My battery is relocated to the hatch and I run a 0 gauge wire to the alternator.

 

[Bmonaco1]

Hey guys, another bump for more help please ...

Does this wiring for the alternator have anything to do with the battery voltage seen inside DSMLink? According to my log, my battery voltage is constant at 0.1v - no good, obviously. 99.99% sure I have everything wired up correctly into my GM alternator, which makes me think the ECU went bad. I'm just unsure where DSMLink is getting its battery voltage reading from to rule out the wiring to the alternator is incorrect.

Alternator tested good, and I just put in a brand new battery.

Thank you again for the help!

 

[Rich J]

I didn't know where to put this just yet so i started here since it is a bit custom. The Original article can be found HERE

UPDATE/EDIT: YOu can getthe plug at any advance or oreilly auto parts.. you have to ask for a 'GM "CS alternator pigtail... they won't find it looking up "saturn"

above is the method I used to swap mine. There was however a problem with the wiring in this and every other write up on tuners and talk forums.

All existing how-to's say that the black yellow wire on the mitsu harness goes to pin "L" this is true as this is one way that the alt turns on and becomes active, but this circuit MUST HAVE AT LEAST 35Ohms resistance and up to 350 max. (which it does) and this wire alone is enough to work the alt besides the main power feed wire for charging.

However here's where things get off track.. The articles say to hook a switched 12 volt to "pin F" ...This is not really wrong but doesn't do anything! IT is ONLY another way to start the alternator should you not have a "battery lamp" wire that has the 12v with 35Ohm resistance to it.... The "F" terminal is for field and it has it's own resistance built in internally so i've read, but either way it doesn't need a resistor or buib and it starts the alt charging just like the black/yellow battery light wire does..

Now the alt will work OK with it wired this way but after scruitinizing the voltage at all times both on a data logger and FLUKE voltmeter since i did the install i can only say i was less than pleased with the output...sure it was better than OEM but nothingn to write home about. So i set about reading for probably 6 hours in 2 days and calling some of the top high output alt guys listed on the web. That's where i learned about "F"

The important wire is "S" this is the wire that reads the voltage at what ever given area it's attatched to and either lets the alt shut down a little or makes it work harder. And sure it will work withtout it but just not up to my standards or anyone like me ...Most people say loop "S" back to the +batt terminal on the alternator, but the problem with that is it's always going to read 14volts and not adjust at all.... The issue withour cars is voltage drop in the rest of the system and as we all know poor grounding.

Tonight after learning all of this i tore into alternator wiring and just finished with awesome reasults... Here's what i did ... I left the "L" wire hooked up... Pulled the fuse on my "F" wire line just in case i wanted to put it back some day and it was nicely tucked... Then i took "S" and soldered a length of 12 gauge wire to it and routed it back across the car and tied it into my distribution block where it could sense the "dropped volts" and also see how low the main system was getting under load. Then i took a length of 8 gauge wire and mounted 2 ring terminals on the ends.. One end got bolted to the hole in the back of the alt (obviously there for a ground IMO) and then hooked the other end to the main ground from the battery that hooks up at the trans.

I snugged everything up and started the car.. I took a voltage reading at the battery ..14.7 volts..NICE! Then i turned on EVERY accessory the car has..lights, A/C radio, rear defog, wipers, and hazards... And not a single flinch from any thing (normally i can tell low volts because my tach adapter makes my tach go nuts when the volts drop too low) I went back and checked the voltage again at the battery and it was 14.5 I could not have been happier and this was at IDLE..normally to get it back up the old wiring way i had to rev the car and it still would not make 14volts... Now it does it at it's low chugging with the AC on idle

HOpe some of you with saturn alt swaps check what i'm saying and log your volts or check with everything on... if they're fine, cool... If not you now know how to make it right !!

TurboGlen, can you be a little more specific as to where on the distribution block you connected the "S" wire to? Did you have a separate distribution block or are you referring to the fuse box in the engine bay or the junction fuse box under the dash?

 

[1990TSIAWDTALON]

The last time he was on here was 2019, just so you know.

 

[DSM98GSX]

Bump on an old thread. Question:

Can someone report what voltages are seen on their Saturn alt based on RPM's and what their crank and alt pulley sizes are? I have the 200amp 1-wire one for reference.
I have talked to MotorCityReman, and the guy was adamant that the alternator starts charging at 2000-2500 RPM.
For reference, I believe the 2G OEM crank pulley - 5.9", OEM alt pulley - 2.65", Saturn alt pulley - 2.00".

I'm trying to find out if this Saturn alt is going to charge at 1742 alternator RPM's.

My redline is ~9500 and idle ~900-1000; with a SuperDamper crank pulley (6.325" diameter) for reference.

 

[Stapl3]

Bump on an old thread. Question:

Can someone report what voltages are seen on their Saturn alt based on RPM's and what their crank and alt pulley sizes are? I have the 200amp 1-wire one for reference.
I have talked to MotorCityReman, and the guy was adamant that the alternator starts charging at 2000-2500 RPM.
For reference, I believe the 2G OEM crank pulley - 5.9", OEM alt pulley - 2.65", Saturn alt pulley - 2.00".

I'm trying to find out if this Saturn alt is going to charge at 1742 alternator RPM's.

My redline is ~9500 and idle ~900-1000; with a SuperDamper crank pulley (6.325" diameter) for reference.

Straight up, 900 idle and 9500 redline just wont work with their units IMO.

My 160a motorcityreman alternator with the smallest pulley they offered would give me 14.x v all day long and the car idled money at 750rpm. Up top, the voltage would fall off the table at 6700rpm like clockwork. No good. I bought the second smallest pulley they stocked (I will measure this for you to give you the answer you seek) and had the voltage I wanted to my 8250 rev limit, but now had to idle the car at 950 to comfortably get voltage in the 14s. I settled there, but ideally I should have sourced a pulley between the two sizes to see if I can get the idle lower while still providing the voltage I wanted up top.

It's a matter of give and take with the single wire alternator. There is no S wire to mess with. The only variable is the pulley size, and you will get 14.x volts from the alternator's operational X rpm to Y rpm. You have to ask yourself two things: what is my rev limit and what is the highest idle I can deal with. As you know, if you spin your **** to 9500 and don't care about idle, then you'll need a different size pulley from the guy daily driving only revving to 8k.

* I see people blindly buying a pulley size from vendors and assuming it's all good because it's a performance part! This is the incorrect method IMO - unless of course it gives you the desired results which I'm trying to say is a fat stab in the dark.
* I don't think going to a higher and higher AMP unit is the proper method. Our cars don't need that many amps. I see people with stock 105a Saturn alternators getting almost 15v from idle to redline and that's the ticket. Going to 160 or 200 I don't think is the right angle to the problem.

 

[DSM98GSX]

Straight up, 900 idle and 9500 redline just wont work with their units IMO.

My 160a motorcityreman alternator with the smallest pulley they offered would give me 14.x v all day long and the car idled money at 750rpm. Up top, the voltage would fall off the table at 6700rpm like clockwork. No good. I bought the second smallest pulley they stocked (I will measure this for you to give you the answer you seek) and had the voltage I wanted to my 8250 rev limit, but now had to idle the car at 950 to comfortably get voltage in the 14s. I settled there, but ideally I should have sourced a pulley between the two sizes to see if I can get the idle lower while still providing the voltage I wanted up top.

It's a matter of give and take with the single wire alternator. There is no S wire to mess with. The only variable is the pulley size, and you will get 14.x volts from the alternator's operational X rpm to Y rpm. You have to ask yourself two things: what is my rev limit and what is the highest idle I can deal with. As you know, if you spin your **** to 9500 and don't care about idle, then you'll need a different size pulley from the guy daily driving only revving to 8k. I see people blindly buying one pulley size from vendors and assuming it's all good because it's a performance part! This is the incorrect method IMO - unless of course it gives you the desired results which I'm trying to say is a fat stab in the dark.

I'll also add that I don't think going to a higher and higher AMP unit is the proper method. Our cars don't need that many amps. I see people with stock 105a Saturn alternators getting almost 15v from idle to redline and that's the ticket. Going to 160 or 200 I don't think is the right angle to the problem.

Thanks for the info! I may have to settle on an 83mm (3.27" pulley) from Bobby at FIBA Motorsports. He made some that are very very close to the size I think I'll need; 84.8mm (3.34").
I've gone through a ton of calculations to determine what will and will not work. This should put me at an engine rpm of 1000 with the alt spinning at close to 2000rpm and 146 amps. Just not sure of the voltage output with that, so still need some data. MCR has no performance plots available for their alternators. May see if a local shop can give me something.

As for the amps, I need the idle amps mostly. I have an electric AC, electric assist steering, electric water pump, etc. So my idle amps are significantly higher than what others may need. The engine redline and limits of the alternator are what's going to work against me unfortunately.

 

[MindBlowin03]

I use a Fluidampr crank pulley and 2.625" single wire MCR alternator. Idle needs to be 950 or higher to charge and I don't have any voltage issues up to 8500.

I would guess you'll need a larger pulley if running it to 9500. I would definitely recommend the pulley from Bobby.

 

[DSM98GSX]

I use a Fluidampr crank pulley and 2.625" single wire MCR alternator. Idle needs to be 950 or higher to charge and I don't have any voltage issues up to 8500.

I would guess you'll need a larger pulley if running it to 9500. I would definitely recommend the pulley from Bobby.

Thank you for the feedback!

I think I can set up the Nexus ECU to watch battery voltage and up the rpms at idle when it drops below a certain voltage. 950 rpm idle isn't bad, but I'd hate to have it at 1100 rpm all the time with the larger pulley. I think Bobby's pulley is the thin line that's needed for my application.

 

[Car Cannibal]

Those with a 1g, what's the quick and fast way with links to go Saturn alternator in late 2025 with relocation to the rear?

I see Morrison Fab has a bracket for stock location, nice, but header and DP heat is rough even when coated so I'll swap to the rear.

Who offers the best new Sat 140 to 160a alternator these days?
Powermaster has a 100a but that's not enough.

I looked on the Jay Racing website, couldn't find the brackets.

I like the idea of going 6awg wire with case grounding for efficiency from alt post to battery. I gained back .8v in wiring losses from doing those wires above on a different car.

 

[Car Cannibal]

Extreme psi offers the Jay Racing relocation kit (at time of my post date).

There's online CS130 rebuilds that go 140,170 and 200a. They offer an iceberg update at 170a and $200.

CS130 and CS130D Series High Output Alternators

Delco type CS130 and CS130D Series Alternators. Used on Chevy and GM Vehicles from 1986 to 2004.

alternatorparts.com

You can get a 6awg 2ft ground and 4awg 8ft posi wire for the posts and that should see maybe a .02v efficiency drop at most (have this on another car, huge improvement).

 

[Tiki2777]

TurboGlen, can you be a little more specific as to where on the distribution block you connected the "S" wire to? Did you have a separate distribution block or are you referring to the fuse box in the engine bay or the junction fuse box under the dash?

Just so everyone reading Glenn's writeups/threads understands, he unfortunately passed away a couple years back. That's why he hasn't hopped back onto DSMtuners.