Alternator Size
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 895
Likes: 4
From: whitman massachusetts
Alternator Size
I am changing over to electric fans for cooling. Car has no AC or electric windows. Will I need to upgrade the rating of my 1971 stock alternator? If so, how many amp alternator will I need? If it changes physical size of alternator, where is best spot to find a new adjustment bracket, the long flat curved one? Any info is appreciated!
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
Mike...How many amps are your fans rated at? If you haven't purchased them yet, the supplier can provide that information when you buy them. Most dual fans run any where between 20 to 25 amps average. If you don't have any electrical options an original 70 amp alternator should work okay. You can buy the adjustment bracket from any Corvette parts suppliers. With an original 70 amp SI alternator you may encounter a little undercharging at idle while the fans are running. I converted my 79 to dual electric fans this past winter and I am really happy with how much quieter and smoother the engine runs without the big fan and fan clutch.
Ken
Ken
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
I believe you have a built in regulator alternator, and the plug is on the side of the case. There is a 94 amp available that by physical appearance is the same as your old one negating any aftermarket brackets that most of the time has to be modified and never fits exactly as claimed....It bolts on in five minutes and nothing trick. Just good stuff....
your OE alternator is probably only 37-41 amps if no AC
your OE alternator is probably only 37-41 amps if no AC
Last edited by Ironcross; Mar 1, 2009 at 07:48 PM.
Drifting
Joined: Sep 2001
Posts: 1,427
Likes: 1
From: Boxford Mass
I upgraded to dual spals and the stock alternator was not sufficient. I went with a 100amp unit and it worked fine. I attached the relays to the inner fender and powered the fan relays directly from the alternator. I used the ACC circuit as the relay trigger from the fuse panel.
The only other small issue I had was related to my MSD box running on, which is a known problem and required a diode in ignition line (only if you have an MSD by chance)
The only other small issue I had was related to my MSD box running on, which is a known problem and required a diode in ignition line (only if you have an MSD by chance)
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I had the stock 43 amper in mine. I upgraded to the dual Spal setup and ran a Crane HI6 box. This would have been to much for the stock 43 amp one. I upgraded my existing alternator to an 80 amp model. It is a simple kit that requires you disassemble your alt. and install some higher amp parts. Took all of about an hour and cost about 40 bucks and I kept my same alt. It has been working for about 5 years now with no problems. I also did this to another forum members car and his is working fine also.
Burning Brakes
Joined: Oct 2006
Posts: 1,044
Likes: 0
From: Henrico VA
His alternator should be 42 Amps and 63 was with AC. I went to a 63, though I shouldn't need it as I've replaced most of the lighting with LEDs and none of my accessories (other than the stereo system are big power hogs). I recommend an alternator upgrade if your fans take 20 Amps.
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Hey Gordonm I have a flex a lite low profile dual electric fan that puts out 2500 cfms and I want to install it. Can you give me some info on what I need to get to beef up my alt? I've had alt apart before so thats not aa problem.
Thanks
Thanks
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
lots of threads on this already.
i posted a few myself.
you will need a better alternator. the cs130 to cs144 is what you want.
napa has a plug that attaches the oem wiring harness to the new alternator and it takes the place of a voltage light if you have the gauge.
contact durango boy. he pretty much walked me through the install.
i posted a few myself.
you will need a better alternator. the cs130 to cs144 is what you want.
napa has a plug that attaches the oem wiring harness to the new alternator and it takes the place of a voltage light if you have the gauge.
contact durango boy. he pretty much walked me through the install.
Burning Brakes
Joined: Dec 2005
Posts: 992
Likes: 56
From: Baldwinsville, NY
I also thinking of electric and have looked at these alternators, has anyone used DB Electric for starters or alternators?
105 amp 3 wire original look-a-like:
http://www.db-starter-alternator.com...5-85%20%2010SI
140 amp 3 wire
http://www.db-starter-alternator.com...%20AMP%2065-85
CS130:
http://www.wagglepop.com/bin/Shop/Qu..._zipcode=13027
105 amp 3 wire original look-a-like:
http://www.db-starter-alternator.com...5-85%20%2010SI
140 amp 3 wire
http://www.db-starter-alternator.com...%20AMP%2065-85
CS130:
http://www.wagglepop.com/bin/Shop/Qu..._zipcode=13027
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
No you do not need a 100+ amp alt. If you are only goingto use 40 to 50 amps you do not need a 130 amp alt. The 80 amp upgrade to the existing alt is fine. If you are running a mondo stereo system with a ton of amps I can see the 100+ amp units. For the extra 25 or 30 amps the fans draw only part time you only need 80 amps. I was stuck in an hour traffic jam and my fans were running quite a bit and the alt kept up fine.
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
No you do not need a 100+ amp alt. If you are only goingto use 40 to 50 amps you do not need a 130 amp alt. The 80 amp upgrade to the existing alt is fine. If you are running a mondo stereo system with a ton of amps I can see the 100+ amp units. For the extra 25 or 30 amps the fans draw only part time you only need 80 amps. I was stuck in an hour traffic jam and my fans were running quite a bit and the alt kept up fine.
The upgraded stators for the SI units overheat. The case wasn't designed to cool as well as the CS units. I just put on a CS121 1-wire 80a unit and it seems to work great. I do not have electric fans or a/c or any other major electrical load though.
The thing is, you don't want the alternator working at more than 1/2 capacity all the time. It just won't last. The CS130/144 is the way to go. They will generate more amps at idle too.
Burning Brakes
Joined: Oct 2006
Posts: 1,044
Likes: 0
From: Henrico VA
My understanding is that the bigger alternators cost power (may only be 3 hp) and wear out faster. I had a 42 Amp alternator that handled a big stereo. My 63 Amp alternator more than handles my current set up. I also went LEDs all over to further reduce the load.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I'm going to disagree with that.
The upgraded stators for the SI units overheat. The case wasn't designed to cool as well as the CS units. I just put on a CS121 1-wire 80a unit and it seems to work great. I do not have electric fans or a/c or any other major electrical load though.
The thing is, you don't want the alternator working at more than 1/2 capacity all the time. It just won't last. The CS130/144 is the way to go. They will generate more amps at idle too.
The upgraded stators for the SI units overheat. The case wasn't designed to cool as well as the CS units. I just put on a CS121 1-wire 80a unit and it seems to work great. I do not have electric fans or a/c or any other major electrical load though.
The thing is, you don't want the alternator working at more than 1/2 capacity all the time. It just won't last. The CS130/144 is the way to go. They will generate more amps at idle too.
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
They won't cost any more hp than older alts. If your car doesn't consume the load.
1hp = 746kw
746/14 = 53a
at 150 amps you do indeed consume 3 hp but not when it is under light load.
Captain........ I can't change the laws of physics.
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
the actual cost is cheap, look up a C4 alternator. i paid like 80 bucks for a duralast.
http://forums.corvetteforum.com/c3-t...lternator.html
above is a link to a write up on how to change it over.
http://forums.corvetteforum.com/c3-t...lternator.html
above is a link to a write up on how to change it over.
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
Here's a couple of photos of a CS144, 140 amp alternator I got from Durango Boy. It came off of a 97 Tahoe. (Notice the off set mounting tabs). The off set worked out well as I was easily able to convert to Lokar adjustment rod. I rebuilt the alternator myself, painted it and had it tested at my local auto parts store. It works well and runs super quiet.
