alternator speed

[BrendellaJet]

I've got a delco alternator I want to run direct drive off the crank. ill it still charge enough? in a jetboat...

[obnoxious001]

Sure, think about what kind of rpms a car runs around town, or even on the freeway versus rpm in a boat. Rex makes a great kit.

[BrendellaJet]

Yeah, I figured it would. Im gonna buy the coupler from Rex and do the plate myself.

[River Rat 005]

I've run an alternator 1:1 on my drag boat for about 4 years now. I haven't had a dead battery yet.

[Cs19]

check with the alt. company and see what ratio they want it at... I spin mine at 2 to 1 but my alt. is capable of turning 20,000 RPMS for short bursts (drag racing). my alt. doesnt even kick on till 1500 RPM, if I was turning it 1:1 that would be a problem.

[Rexone]

Just rap the throttle once and it energizes the field and starts charging. Not a big deal. Alts are designed to run down the freeway in a passenger car like OB001 said at 2-3000 rpm with stock pulleys for longevity. Running off the crank cuts the alt speed down. Not a bad deal for boats running 5-7000 rpm.

[BrendellaJet]

Rex,
Got the coupler today. The piece that mounts to the dampener has a hold drilled in the center that the bolt is supposed to slide into but not pass through(duh)-but the head of the bolt is too big to slide all the way into the hole(hole is stepped at the bottom to prevent the bolt from passing all the way though). The way it sits the rubber dampener and the alternator half of the coupler cannot fully engage the other half of the coupler...
Ill look for another bolt with the same thread, but otherwise Im gonna take an endmill and open this thing up. Just want to make sure that wont muck it up.

[Unchained]

Rex,
Got the coupler today. The piece that mounts to the dampener has a hold drilled in the center that the bolt is supposed to slide into but not pass through(duh)-but the head of the bolt is too big to slide all the way into the hole(hole is stepped at the bottom to prevent the bolt from passing all the way though). The way it sits the rubber dampener and the alternator half of the coupler cannot fully engage the other half of the coupler...
Ill look for another bolt with the same thread, but otherwise Im gonna take an endmill and open this thing up. Just want to make sure that wont muck it up.
Are you using a socket head (allen) bolt ?

[Rexone]

Rex,
Got the coupler today. The piece that mounts to the dampener has a hold drilled in the center that the bolt is supposed to slide into but not pass through(duh)-but the head of the bolt is too big to slide all the way into the hole(hole is stepped at the bottom to prevent the bolt from passing all the way though). The way it sits the rubber dampener and the alternator half of the coupler cannot fully engage the other half of the coupler...
Ill look for another bolt with the same thread, but otherwise Im gonna take an endmill and open this thing up. Just want to make sure that wont muck it up.
It's designed to use a grade 8 socket head bolt which is suppose to come with the coupler. I'm guessing they did not send you the bolt? :mad:

[Cs19]

Just rap the throttle once and it energizes the field and starts charging. Not a big deal. Alts are designed to run down the freeway in a passenger car like OB001 said at 2-3000 rpm with stock pulleys for longevity. Running off the crank cuts the alt speed down. Not a bad deal for boats running 5-7000 rpm.
My deal cuts out when it drops below a certain RPM, I can see the voltage curve on my data logger, you can clearly see when the thing turns on and off. I run a one wire alternator, i think thats why.
Chris

[eliminatethis]

I always install a moroso 5" pulley on all my perf. upgrade eng. never had a charging prob. never loose a belt also

[BrendellaJet]

It's designed to use a grade 8 socket head bolt which is suppose to come with the coupler. I'm guessing they did not send you the bolt? :mad:
The socket head is too big...

[v-drive]

To big by how much

[Rexone]

The socket head is too big...
You're right. I just ran a new batch, which you got one of and they're all machined too small :mad:
I found an older one. I can send it today if you like.

[BrendellaJet]

I think I can take care of it. Just wanted to confirm that it was legitimate problem. Thanks for offering though.:D

[sawtooth]

When I inquired about doing this with the Rex set up and a Delco alternator I was told that it would not fit the shaft on the Delco - had to buy the alternator that Rex sells for the set up. Did something change or is this just another "your not cool enough" in a lifetime of "Hey, back of the line pal"! life that I lead. :D

[BrendellaJet]

When I inquired about doing this with the Rex set up and a Delco alternator I was told that it would not fit the shaft on the Delco - had to buy the alternator that Rex sells for the set up. Did something change or is this just another "your not cool enough" in a lifetime of "Hey, back of the line pal"! life that I lead. :D
it just needs to be drilled out about an 1/8th inch to fit the delco. Plus the delco has no keyway so you have to cut the shaft on the alternator too.

[sawtooth]

it just needs to be drilled out about an 1/8th inch to fit the delco. Plus the delco has no keyway so you have to cut the shaft on the alternator too.
Hey thanks for the heads up, broaching the shaft is no prob, I like this set up and will have to think about going this way again with the installation/rerig on my cruiser.

[BrendellaJet]

Hey thanks for the heads up, broaching the shaft is no prob, I like this set up and will have to think about going this way again with the installation/rerig on my cruiser.
No worries. Im very pleased with the quality of the coupler. I bought the rex standoffs too, also nice pieces. Ill post how it looks when finished. Im making my own plate though so I can also mount my ignition on it. Should be pretty nice when done, I hope.
Like anything else, one custom piece takes two more custom pieces to make it work...

[LeE ss13]

Just rap the throttle once and it energizes the field and starts charging.
Mike, Mike, Mike..... Just rap the throttle ??? Why not wire it up correctly and it will charge all the time? If you are using the standard GM starter solenoid, run a wire from the small post, the one that never gets used for anything, opposite the starter wire, to the tang on the Alternator that is next to the Hot wire. The small post on the solenoid has power coming out of it when the engine is cranking. It will energize the alternator. If you are not using the GM solenoid, buy a $3.00 diode from the electronics store and run a wire from the alternator thru the diode to the ignition switch. If you have the diode going the right way it will also energized the alt. If not, the engine will not shut off. Just an idea.