Hello .. in my Cuda i have start problem at hot and low voltage . i have POWERMASTER starter and 100 ah alternator when everything is on and engine HOT the voltage go down at 11.8 volt ... not good if you stop the engine and wait 10 minute and start ... i have :
electric water pump
dual electric fans
Aeromotive A1000 Fuel pump
MSD 7 al
CVR electric brake vacuum pump

when headlight is on.... not good ...

i have checked all wire .. all ground ... replaced two alternators... no change..

need 150 ah alternator ?

best starter ? CR is 12:1

Thanks

What cranking amp battery are you using? Are you using relays to fire up the accessories?

Sounds to me like you have more load than you have alternator to support it and it;s draining the battery to suppor the extra load.

You need to figure out how much all your electrical accessories are drawing, and if you really need all those thing to be electric, then get an alternator that can handle the load.

Optima 800 ah .. yes all relays

i think 80 ah for everything draw... need bigger alternator

100 amps but what is the ramp up to that 100amps? You need to find out what it puts out at idle and cruise before you can determine if it's right. If it never puts out those 100amps until 3500rpm then it won't do you much good.

My $45 cs130 for a Ford Tractor and my part store starter for a 318 worked better than any of the Powermaster alternators or starters I wasted my money on for my 451/472. Hot lapping and never missed a beat.

Sounds like you need professional help. Find a repair shop with an amp clamp (or buy one yourself) and figure out what is really going on. Nobody on the internet is going to be able to solve it since we can't see how you have the wires routed and we can't debug anything. You need to use a volt meter and an amp clamp to find out what is happening. Most likely a wiring problem somewhere since 100A alternator shouldn't have an issue. Replacing multiple alternators tells me that you're chasing your tail.

You need a modern charging system with an internal regulator like a Denso Toyota alternator. Like Andy posted you may have wire gauge issues or a system that is not designed for your current requirements. Modern cars of today have twice the amount of accessories taxing the electrical system and do it without any effort. You need a dedicated charging system wire harness in my opinion. Modern cars have several separate systems that are isolated from the other systems.
Gus

I chased my tail all summer with charging problems, I thought I had it solved with a new alternator, Then it wouldn't start again at a gas station.
I finally found out that the engine wasn't grounded good enough. One ground strap from the engine to the frame solved all problems. I know you mentioned you checked your grounds but make sure the engine is grounded very well.

Correct, a 100A alternator that is hooked up to the original ammeter and feeding the charge thru the old firewall connectors is not a good solution. That is the problem with questions like this, there isn't anyway for the OP to tell us all the details of the installation. All it takes is for a bad wire or a bad ground or a poor connection somewhere and nothing will work correctly. I have a small 60A alternator on my Duster and it holds 14.5 volts even at idle. But all of my wiring is new and the alternator connects directly to the battery.

That response was funny.

I called Power Master this summer about what size wire gauge from my 100 amp alternator after accidently grounding out the main wire while using a timing light power lead on it, that resulted in smoking and melting the 10 gauge wire all the way back to the battery
They recommended using a # 4 gauge wire along with using a #4 gauge ground wire from the treaded grounding boss hole on the alternator to a threaded hole on the block
I'm going to do that this winter, in fact I'm going to run two #4 gauge wires from the alternator,, one to each battery
Raff, I always slow charge my batteries for 10 to 30 hour with a 2 to 6 amp charger before taking the car to the races, that way I know they are fully charged to start with