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2G Problem with saturn alternator @ high rpm

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jery1234

10+ Year Contributor
268
39
Jul 26, 2008
Toronto, ON_Canada
I have installed bigger meth jets & had to re tune the car . So I made first & second gear pull . While I was analyzing the data log I have noticed that my voltage is dropping to 11.7 volts after exceeding about 7.5 k RPM. I just have installed brand new Saturn alternator (90 amp, big pulley) version. Is this known problem with those alternators? If so, what's the cure for this
 

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Having the same issue with my Saturn alternator (stock pulley) so I'm bumping this post. Attached is an EvoScan log. Dropping down to 11.5 volts at around 6.8 K RPM. All the lights in the cabin dim as I'm doing a pull.
 

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What is the diameter of your pulley being used?
 
Twicks if you're asking me, Motor City Reman sold me one with a 2" od pulley. Sorry if I'm thread jacking Jery...
 
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The only thing you can do is to put a bigger pulley on it , so I have ordered 1g pulley from Kiggly & made the shaft hole Saturn size &about 1/4 inch distance washer to line it up . Works perfect @ 9.5 k rpm .
 

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Do you know what the dimensions are for that kiggly pulley?
 
Twicks, what is your idle, and rev limit at with that 2.55" pulley?

Jery, what is your idle set at for that 3 in Kiggly? Any idle issues?

The reason I ask is I'm doing some calculations..

(According to Jegs website)
Delco SC130 105 Alternators Specs are:
80A @ 2,400 RPM @ 13.2 VDC @ 77F
Maximum RPM: 18,000

I'm running a Fulidampr pulley with an O.D of 6.375 in.

With a 3" OD pulley max engine RPM is 8,470, and would need an engine idle of 1,129 RPM to reach 80A.
With a 2.55" OD pulley max engine RPM is 7,200, and would need an engine idle of 960 RPM to reach 80A.

Anyone please feel free to correct me if I am wrong.
 
I have it on two motors with a 950-1000 rpm idle, and a 9400rpm limit on the aluminum rod motor and 8800 on the steel rod motor, both are 2.3L setups.

They both are using aggressive cams at/over 288*, my aluminum rod motor has a high lift 294* cam similar to a Kelford TX294 (mine is an ancient Crower custom cam), the other is a Kelford TX288 on the steel rod motor.
 
The only thing you can do is to put a bigger pulley on it , so I have ordered 1g pulley from Kiggly & made the shaft hole Saturn size &about 1/4 inch distance washer to line it up . Works perfect @ 9.5 k rpm .
Does the washer go between the cooling fins and pulley ?
 
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