Larger pulley on 1 wire alternator

[superorange]

Has anyone changed the pulley on the gm 1 wire alternator ? Mine is shutting off after 7500 rpm. So I want to put a bigger pulley on. I was thinking a 2.5" or 3"


This is the alternator I'm using.
http://m.motorcityreman.com/high-amp-alternators-1-wire-universal-mount-gm.html

 

[bling5tatus]

Well, what's your question? Whether someone has changed a pulley or something else? I'm sure someone, somewhere, has changed one so I can make a wild stab in the dark and answer "yes" to your question.

 

[hotrodssnova]

Jegs, summit sell different sized pulleys. It's done all the time.

 

[twicks69]

Measure the bore of the pulley (or shaft), and then measure the current diameter of your pulley.

Now, let's say that you want it to run a desired rpm of 10,000rpm (x), and its turn off is currently at an rpm of 7,500rpm (y) on a 45mm diameter pulley and the calculated size of the pulley is (z), then calculate as this:

7500rpm = 10000rpm / (7500rpm / 45mm) = 60mm
or simply calculated as:
(x / y) * current diameter pulley = z ----- (10000 / 7500) * 45 = z = 60mm


With my Saturn alternator, which has a 17mm bore pulley, with a 4 rib 14mm belt, I purchased 63mm and 65mm pulleys. I have installed the 65mm pulley and it clears the oil pump sprocket pulley hump on the timing cover in a rear mount installation.

I purchased these from http://alternatorparts.com/
Part # 2482258 - 4-Groove Alternator Pulley For Denso 90-120A Alternators 14mm Belt x 65mm Rib OD x 17mm Bore
Part # 2481250 - 4-Groove Pulley For Hitachi and Mitsubishi Type Alternators - 14mm Belt x 63mm Rib OD x 17mm Bore

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[superorange]

I ended up with a 3.25" ford pulley that fit on well. I'll let you guys know the results when I get back on the dyno this week. It's already on and in the car so I might as well try it. The old pulley was 2 inches in diameter

 

[superorange]

It looks like I'm still having this issue. Any suggestions ?

Has anyone ever tried an evo alternator ?

 

[yhype]

Maybe its not your alternator?

 

[superorange]

I have huge grounds, and I'm not the only one having this issue. The larger pulley helped a little which would suggest that the alternator is the issue. Those gm alternators just aren't made to rev to the rpm I'm reving to. It's a one wire alternator so I know it's not wiring issue. It charges great up until about 7400 rpm