Re: Alternator choice?
 

You didn't clarify your estimated amp draw on your car. I had a conversation with Larry Hill about this very subject late last year.

If you're running a carburetor with a stock type coil you can get away with a lot less.

I run an EFI system that uses wide band 02 sensors in each primary for data and 2 more in the collectors for the EFI system. Add a EFI High Pressure fuel pump, Large Cooling Fan, electric water pump, 2 Digital Dashes and a Race Pak the little items add way up.

Last car we logged years ago didn't have the Race Pak, 02's on primaries or digital dashes. I was drawing 60 to 65 amps during a chassis dyno run.

Since I was at Holley when I built this car I opted for the MSD 5361 160 amp alternator.

Fuel injection loves Voltage. I also have 2 Optima Red Tops that have worked well. Most times after a run the batteries state of charge is at 95% unless I run the fan and water pump in the pits to cool down.

I think that you cannot go wrong by having too much capacity.

Good luck!

Robin

Re: Alternator choice?
 

Last summer while on the dyno (down at Gales) we had an unexpected 10 HP drop out of nowhere. Looking at comparison data it looked identical.... except Tony had forgot to turn the charger back on in the dyno room. The voltage had fallen to 11.5 volts during the pull. This was an L-98. That dyno room has a 7AL2 for ignition juice. Turned the charger back on and we instantly was back to normal power levels.

Re: Alternator choice?
 

Race engines run on gasoline, most of the time. Race CARS run on electricity.

Re: Alternator choice?
 

Thanks for the replies everyone. I am running 6AL and a holley fuel pump as well as dual fans off of something from the junkyard (charger I think?) The waterpump drive is being replaced with an electric water pump. Oh yeah, the big killer, power windows up and down a dozen times trying to keep cool, lol!

Total amp draw? Don't know but I'm always thinking "rather too much and not need it than need it and not have it." (paraphrasing Sun Tzu, lol)

Go for eye surgery Monday AM so everything will be on hold for a bit, pull the trigger when I can...or stay with stock alternator with a new belt.....hmmmm....

Re: Alternator choice?
 

Ya know, a LONG time ago, I was playing with a FWD Pontiac Sunbird Turbo. PFI, tons of boost and OBD 1 but still an ECU. I couldn't feed that car enough juice to make it happy. I even had a local shop hop-up a big GM alternator for it. The supercharged Buick and the Cavalier (yes, even the Cavalier) that I play with want LOTS of amperage.
To be clear, what you're building probably won't need a lot of amperage to get it down the track if you have a large, fully charged battery in it. On my old 6 cylinder stuff I would shut off the alternator if I had to go fast but I also was turning off everything but the fuel pump and the ignition box.
You're better to have too much and not need it.

Re: Alternator choice?
 

You didn't say what gauge wire from the alternator to the battery. Where's the battery? The longer the run the bigger wire you need to carry amperage.

Re: Alternator choice?
 

I have OO ga wire (I think) to ground on engine block and to the starter solenoid. The factory starter wire going to the starter. Batt in stock location front right of car and alternator wire is factory whatever that is 10-12ga?

Battery is 550CCA and new last year.


Edit: Went and took a look and then took a couple pictures. Forgot that the original wiring also includes a plug and significantly smaller wire from Alt to Batt than I thought.

Yes, it may be ugly, but at least it's slow....no, wait....lol!

Re: Alternator choice?
 

I think the Power Master on line catalog has gage wire and maximum length recommendations. Easy to read and follow.

Re: Alternator choice?
 

My son has run a CS130 alternator on his 68 Barracuda drag and drive car for many years and it has worked great for him. I think it was from O'Reilly's

With electric fan, water pump, fuel pumps, ECU and Coil Near Plug Ignition it supports a full load.

One of the reasons he chose it was that it came on thousands, if not millions of GM cars and they are easily available at most any auto parts store.