alternator

[Ed Wright]

Originally Posted by Coleydog

Why would you want to cut power a full throttle? 14 volts is better than 12 or less, to run all the electrical stuff when it's extremely needed. The value it picks up will more than offset any drag loss. Moreover, any alternator will not charge up the battery with the little running time the car sees. It stops the bat. run down you would see without one. 16 volt, that's another story.
Mike

I tested that, my car picked up a couple hundredths cutting it off @ WOT. I would not bother doing that without testing it.

[Eman]

Why a one wire? You can cut power to the exciter circuit eliminating any load at WOT.

[Ed Wright]

Most race cars don't still have all that factory wiring, one wire alternators are more popular for race cars, engine swaps, etc.

[Coleydog]

Originally Posted by Ed Wright

I tested that, my car picked up a couple hundredths cutting it off @ WOT. I would not bother doing that without testing it.

Interesting, did you remove the belt when testing? If not, I would say there's a tremendous amp draw at wot to lose that much ET. Meaning batteries are not up to charge or a big drain (fans, pump, computers).
Something doesn't sound right to me?
What rpm are you turning? Alternator could be tuning way to fast and that's the power loss, 3000 rpm is way more than needed.

[Chris1529]

Originally Posted by Coleydog

Interesting, did you remove the belt when testing? If not, I would say there's a tremendous amp draw at wot to lose that much ET. Meaning batteries are not up to charge or a big drain (fans, pump, computers).
Something doesn't sound right to me?
What rpm are you turning? Alternator could be tuning way to fast and that's the power loss, 3000 rpm is way more than needed.

Picked up a couple hundredths means Ed went faster by cutting it out at WOT.

[Ed Wright]

Originally Posted by Coleydog

Interesting, did you remove the belt when testing? If not, I would say there's a tremendous amp draw at wot to lose that much ET. Meaning batteries are not up to charge or a big drain (fans, pump, computers).
Something doesn't sound right to me?
What rpm are you turning? Alternator could be tuning way to fast and that's the power loss, 3000 rpm is way more than needed.

It was my old '56 Chevy Jr Stocker. 265". Only belt also ran the water pump. Had points, Condenser, and a conventional coil. If MSD existed back then (1964/1967) I had not heard of them. Never spun it much past 6K, it was a solid lifter Corvette engine combo, but we had to use stock valve spring specs. Nothing like we use today.

[Coleydog]

Originally Posted by Ed Wright

It was my old '56 Chevy Jr Stocker. 265". Only belt also ran the water pump. Had points, Condenser, and a conventional coil. If MSD existed back then (1964/1967) I had not heard of them. Never spun it much past 6K, it was a solid lifter Corvette engine combo, but we had to use stock valve spring specs. Nothing like we use today.

Hmm, more to think about then. I guess the next train of thought would be the more engine hp the less hp loss. I know my 64 Savoy with a 440 never had any different ET on or off, (small crank pully and big pully on the alt). As far as consistency, I ran 7.59 with a 1 or 2 all day, alt on, just a bracket car.
By the way, loved Jr Stockers back then.
Mike

[SGSST109E]

Powermaster makes a single wire alternator with and adjustable regulator. I run mine at 15volts, not enough to hurt the battery because its not running that long. If I remember correctly 750 watts equal one HP. So a 100 amp alt. at 12 volts is 1,200 watts less then two HP.

[Ed Wright]

Originally Posted by SGSST109E

Powermaster makes a single wire alternator with and adjustable regulator. I run mine at 15volts, not enough to hurt the battery because its not running that long. If I remember correctly 750 watts equal one HP. So a 100 amp alt. at 12 volts is 1,200 watts less then two HP.

Not disputing your math, but turn that alternator on & off the engine, sitting there running, certainly would speed up & slow down as the alternator was turned off & on.
ET slips certainly showed more than I would expect from 2 hp.

[Eman]

On the one wire alt. if your battery is in the back how are you wiring it? I run a powermaster one wire, been on the car for almost 20 years and had to replace the regulator once. I've spoken to Powermaster,Mechman and East Coast electric and they say to run direct to battery, not the cutoff switch. They said that shutting the power off while the car was running could hurt the alternator and they don't recommend it. Called NHRA and they were very vague about having power at the alternator all of the time even with the main power switch off. I know many tracks when they tech will shut the car off from the cutoff switch as their test.
I'd say shutting off the power to a 1 wire alternator at WOT would not be recommended by the manufacturers.