Alternator Help!

[Mr.Larry]

What size alternator should I get?

I got my car back on the road with the new motor. I went from a 355ci to a built aluminum headed 408ci Stroker. I decided to go with electric fans off of a 4th gen camaro and an aluminum 2 row radiator. I had everything wired up directly to the igniton until i bought a fan controller. With both fans on all the time the car barely went over 170* in 80* weather. My alternator was barely charging so I went ahead and got the controller and wired it up. Low and high speed works like expected. I have the low speed wired to the ignition and the high speed comes on at ~190*. The vehicle ran at a consistant 185* on the freeway in 90* weather cruising at @ 2600 RPM. At idle, the high speed fan on kicks on for a few seconds every minute or two. The radiator is really doing its job with the fans on low.

The problem I am having now is that with my electric fuel pump, and those dual fans pulling so many amps that my charging is suffering. I havent even turned the radio on and I am already having problems. My system consists of a 400w amp and 2 12" Kicker L7's. I doubt that they will need too much juice since everything worked fine before the fuel pump and fans. So, as stated in the begining, what size alternator should I get?
Any help is greatly appreciated, I am tired of carrying cables around. lol

The fan setup before the 2 row

After the 2 row

 

[Longroof79]

How many amps does your current alternator put out? I would look into a CS144 unit. They put out 140 amps, and should take care of your charging needs.

I used the CS130 unit which allegedly puts out 105 amps. My car is still off the road, so I won't know how sufficient it is.

Looks like you have a 10 or 12si unit in there now. They're not rated for a whole lot of amps, unless they had been upgraded.
Another alternative would be an aftermarket unit such as a Powermaster. With all the additional electrical components,you may need something closer to a 200 amp unit.

 

[pontiacgp]

if you want to stick with the style of alternator you have now find a local shop that rebuilds them. I have a shop in my area and he'll build me any alternator I want.

 

[axisg]

if you want to stick with the style of alternator you have now find a local shop that rebuilds them. I have a shop in my area and he'll build me any alternator I want.

^^ what he said and it will be cheaper too. Rebuilt units from most parts stores were $90- $120. Local guy rebuilt mine with better internals for $75 cash.
Just a suggestion but now might be a good time to find and install a serpentine alternator pully ( they came on 85? & up Gbodies, Fbodies ) as they are more forgiving to alignment and hold better than a vbelt. Be sure to keep the steel cooling fan that you have now instead of the plastic one that seems to come on most rebuilt alternators ( I have had 2 grenade on me )

Here's a link to the CS144 conversion for your reading
http://www.montecarloss.com/community/u ... ber=493219

 

[Longroof79]

Apparently, from what I read, the newer style alternators run cooler than the early style units. More cooling holes/ vents.
I've also seen the 12si units rebuilt putting out up to 140 amps.

I've had the plastic fan on my old alt. It's never come apart, but I do prefer the metal fans over the plastic crap.

BTW, what kind of fan controller are you using? I also have LS1 fans going into my car.

 

[Mr.Larry]

Thanks everyone for the help, I am probably going to go with a 140+ amp unit. That should be suffice.

BTW, what kind of fan controller are you using? I also have LS1 fans going into my car.

I wired the fans using the stock wiring diagram from an f-body using the 3 relays. This was to retain the ability to run them with hi and low speed and not buy a controller. After everything was said and done I couldn't decide what grounding thermostat switch to buy so I picked up an adjustable one from advance and just re-wired it to give out a ground signal to my existing relays. It is actually safer this way becasue I dont have to worry about exceeding the amperage of the cheap controller. All it is doing for me is sending a ground signal to my setup when it senses the predetermined temp.

 

[Longroof79]

Thanks man!
I guess you can't go wrong using the stock OE wiring diagram. You wouldn't by any chance have a link to this particular (F-body) wiring diagram? What's the purpose of having three relays? I understand one relay per fan, but where does the third come into play?

 

[Mr.Larry]

Its a wierd setup but it works. What it does is allow the fans to run in series using 2 relays and then switches to parallel with the third. 6v is for low speed and the 12v for high. I have a picture of the diagram but don't remember where I found it lol. Ill upload it here shortly.

 

[Mr.Larry]

I originally found this:
(the bottom one of the 2 in the pic)

Then I came across this:

I compared it with the original and it was spot on simplifying the process of hooking it up to the relays.
I compared them a few times and then wrote my own diagram out to check for accuracy and it is spot on.
I hope this helps!

 

[Longroof79]

Hey, thanks Larry,
I appreciate the explanation concerning the three relays and their function in this configuration. That's a nice clear wiring diagram, too. That should be very helpful...and thanks for the info on where to acquire the relays and parts.
Thanks again brother, it's much appreciated. 😀