2G Problem with saturn alternator @ high rpm

[jery1234]

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

 

[bpk1337]

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.

 

[twicks69]

What is the diameter of your pulley being used?

 

[bpk1337]

Twicks if you're asking me, Motor City Reman sold me one with a 2" od pulley. Sorry if I'm thread jacking Jery...

 

[jery1234]

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 .

 

[bpk1337]

Do you know what the dimensions are for that kiggly pulley?

 

[twicks69]

I used the following:

Part # 2482258 - 4-Groove Alternator Pulley For Denso 90-120A Alternators 14mm Belt x 65mm Rib OD x 17mm Bore.

From AlternatorParts.com -- http://store.alternatorparts.com/part-2482258-4-groove-pulley-for-denso-90-120a-alternators.aspx

No issues on both of my setups using it, with a rear-mounted Saturn 200A alternator with a modified Jay Racing alternator bracket / tensioner.

 

[bpk1337]

You are the man Tim! Thanks.

 

[jery1234]

this one is a little bigger I have this one too but did not tested it just decided to go with kiggly pulley do to rear location of my alt Btw kiggly pulley is 3 inch .http://store.alternatorparts.com/qs...ve-serpentine-for-mitsubishi-alternators.aspx

 

[bpk1337]

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.

 

[twicks69]

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.

 

[bpk1337]

Going to go with that 2.799" just to preserve the life of my alternator. Attaching a graph of the CS130D performance curve, and a link to more info incase anyone else needs it in the future.

http://oljeep.com/AltTheory17/AlternatorTheoryVersion17R1.htm

 

[awdmonster1904]

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 ?