high rpm alternator problem

[stevieturbo]

Im getting a bit of a strange one.

I bought this alternator of egay a while back, and its gave bother a couple of times, but had it repaired locally.

In short...when pushing hard, above circa 5500rpm, the alternator stops charging. The charge light does not illuminate on the dash, but logs show battery voltage dropping from circa 14 volts, down to 11.7 or so once above this rpm
When I let off, power is restored.

I first noticed it tonight, as the lights would get dim when it occured.

Is the alt just scrap ?

All std pulleys and pulley sizes in use.

[LS6427]

Originally Posted by stevieturbo

Im getting a bit of a strange one.

I bought this alternator of egay a while back, and its gave bother a couple of times, but had it repaired locally.

In short...when pushing hard, above circa 5500rpm, the alternator stops charging. The charge light does not illuminate on the dash, but logs show battery voltage dropping from circa 14 volts, down to 11.7 or so once above this rpm
When I let off, power is restored.

I first noticed it tonight, as the lights would get dim when it occured.

Is the alt just scrap ?

All std pulleys and pulley sizes in use.

What kind of alternator do you have? I use a $149 dollar one from the auto parts store and its great. Advance Auto. Lifetime warranty.

But you may have another issue. I've never heard of going into high rpm's causing an alternator to drop off. Could be the alternator though.


.

[stevieturbo]

Just a replacement Delphi, supposedly reconditioned.

TBH...its actually given me nothing but trouble. When I got it, the casing was clocked wrong to fit the engine.

I first fitted it a year ago...when on my first outing, it failed on my first run.

I blew the engine that day :S

I had it repaired locally, so hoped it would be fine now.

Yesterday was the first time Ive actually revved my new engine, so only found out whats happeneing.

I'll refit the old alternator and see how it goes.

[LS1AC-Cobra]

I also bought a alternator from egay last year, installed it last week works fine so far.
I don't know if its a refurbished oem part or a brand new chinese fake,
It looks like brand new though and it was just $89
I had no issues installing it, fits perfect, I just hope it won't give me any trouble in the near future cause you can read here so many guys having issues with egay alternators.
Why don't you take it back to that shop were you had it repaired, they should be able to make a test run and see up to what rpm it is putting out juice.
I know you have to take it out from the car again, extra work, busted knuckles aso.
I also hate such (unnecessary) jobs

[stevieturbo]

I will do....but not sure they have the ability to spin it an equivalent speed. They just have an electric motor to spin them up enough to start charging. WHich for 99% of cases is all thats needed

When you have a large crank pulley spinning at 6000rpm, and the small alternator...thats turning it pretty fast.

[Docrocket1967]

My buddy had the exact same problem on his WS6 the factory alt. were just not meant to push any kind of high RPM and he has alot of upgrades and he had this problem several times and what he did was get an alternator from a Police B4C LS1 Camaro because there alt. were meant to have more of a pull from them because of all the extra electronics they have. He said they are way better than factory and he has not had the problem since and he has more work done to it now and that was about 8 months ago.


If you can find one and have that rebuilt with the same internals you should be in good shape

[stevieturbo]

Ive put the original alternator back on, and all is well.