I'm having an issue here that i'm trying to find a way to resolve. I have a 175amp alternator from tuff stuff that is falling on its face at around 4,500 rpm. Their documentation and many others state not to spin it over 15,000 rpm. 7.425 crank pulley / 2.0 alternator pulley = 3.7125 *rpm 7000= 25,987rpm at the alternator....... How is everyone else not having this problem? I'm basically maxing out the alternator at 4,000 rpm. My solution was a 3.5" alternator pulley that would get me to about 14,850 rpm at 7000rpm.. problem is with the aster bracket I'm almost 100% sure I'll be hitting the procharger pulley bolt against the alternator pulley.

Any help here or suggestions would be more than welcome!

 

I dont have this problem. Why would aster change how fast the pulleys spin?
you.must be doingsomething wrong

 

 

Ok, so the alternator rpm just doesn't match to the rest of the accessories....

if it's a ls alternator why isn't compatible, you need a new one

 

yeah we've had that problem. you can bandaid it with the HD brush kit from store.alternatorparts.com but the fix is a bigger pulley. get the shaft speed down to 20k and thats fine for drag racing

 

You might check with Bob at Brute Speed to see if there is an under drive pulley available that can be used with the ATI damper. But an UD pulley might slow down the water pump? Or perhaps not make a difference because I have read the LS2 water pump is more efficient than the LS1 water pump - so maybe it would be a wash (LS2 water pump with different pulley offset is required with an Aster Bracket).

Or perhaps easiest and be done with it - is to move the alternator topside to passenger side. I'm thinking the same (running 4 fans so want a 145 amp alt or more). I can't get the truck alternator to fit because of clearance issues with the pulleys. The truck alt pulley is approximately 2.25 to 2.375 " - same as stock.

If one moves the alternator topside it requires some modifications:

Make sure the alternator bracket without the alt in the stock location won't affect the j bracket/aster bracket mounting.
Will have to add bushings and shims in spaces where the alt fits between the alt bracket, else the alt bracket will distort when clamping j bracket on to the alt bracket.
Will have to reroute and lengthen battery cable to alternator.
Will have to reroute and lengthen plugin to alternator.
Is there a ground strap - can't remember.
Might have to change oil filler cap or modify. Some alt relocation brackets say you do - others don't mention it.
Might have to relocate catch can(s) if you have one.
Remove stock tensioner and switch to fixed/static?
New belt perhaps if longer or shorter.
Replace with a larger pulley on the alternator
Make sure to have a 10 gauge run of high strand count wire harness to the pump(s).
Might have to lengthen the hot wire kit to the alt if you have a hot wire kit. Not sure. It might be long enough if it is routed down the passenger side.

At 7 K
7.4255/3.5 * 7000 = 14850 (alt)

At idle 850 rpm
7.425/3.5 * 850 = 1803 (alt)

At idle 950 rpm
7.425/3.5 * 950 = 2015 (alt)

Note: some say this alternator/rpm issue is all a crock because some foreign cars regularly spin up to 7k and more. But they account for it with a smaller crank pulley.

Check with Tuff Stuff how a 3.5 inch pulley would affect low idle charging or if they can account for that with an alternator with a different charging curve.