Ducman82

As i am bolting stuff back on to this motor build of mine i got to thinking. i have seen and personally done, alternator upgrades on the OB cars, but what is out there for the late model cars (with the alum bracket for alt and the sliding PS pump)...

i searched but did not find much. i would love to add a little more juice to this build. i have the bosch 115amp that i got with this motor, but looking for more. is this something a alternator shop and hop up?

Rob Edwards

Toss a PM in the mail to Hans, he can help you.

Ducman82

sent an email instead. :-P
thanks a million

Ducman82

:-P

Podguy

I believe it is a 86 Chev Camaro V6 C130 alternator. It is almost a bolt up. You will need a shim for the back of the top mount, a pig tail and a different length fan belt. There should be an article on Renn List. We did this to Erik's car to good benefit. In addition, the price is right. I found a chrome one for $85 no core.

Avar928

928MS has the 200amp upgrade but it's on the pricey side (>$600)

Ducman82

i have the chevy alt, but the the way the top pivot mounts is WAY different. the early style are "captured" by two prong, one on each side of the alternator. the later style has the two prongs on the alternator its self, and then mounts to the car. (if any of that made sense)

Alan

If you already have a late model higher output alternator then a remote mounted adjustable regulator is probably the cheapest option to address the usual droop at hot idle.

This will not give you more overall output - but does allow you to adjust the voltage and avoids the over aggressive temperature compensation problems - assuming you mount the regulator outside the engine compartment (say in the drivers front fender near alt hose).

If you live somewhere hot - where your alternator generally works well in the winter but not well during the summer - this should help.

Alan

Shark_Week

if you go with an adjustable regulator, make sure to definitely get/use a remote mounted type. i installed one but is not remote style. bad mistake. i like that it now stays at 14.6-14.7 volts though.

Alan

Thats too high... I'd not use more than 14v. Detroit iron gets away with higher system voltage by dropping voltage across the battery cables - that doesn't happen much on a Porsche.

You are probably cooking your battery.

Besides a higher regulator set point is rather counter productive - it will typically mean that droop will start to happen sooner since you are extracting more power for the same conditions.

Alan

Ducman82

do they make rebuild kits? or is it worth shipping them out to get done?

Shark_Week

what are bosch regulators set to? i thought they 14.5 v

S4ordie

+1 on the Hansenator. Original Bosch housing and connectors with much improved low and high RPM output.

Hans spent a lot of time researching this. I need(ed) a HO alternator to power all the ancillary goodies I am putting on my project car (carputer, integrated Skarktuner, Sharkwoofer, power 12 way seats, etc.). Living in a climate that regularly gets above 115f / 46c means heavy amp draw while sitting in traffic at night during a Summer Monsoon with wipers on high, listening to music, running the AC.

Alan

It depends which regulator you buy...Bosch supplies similar alternators to many manufacturers. For a 928 it should be set to 13.8v - 14v.

The thing that makes the biggest difference is the temperature compensation degradation - a deliberate factor built in since hot auto batteries cannot handle high charging currents - engine compartment batteries get quite hot - related to ambient + engine heat.

Since the vast majority of batteries live in the engine compartment - virtually all alternators regulate down aggressively at hot.

The alternator can only lower the battery charging current by lowering its output voltage. For a 928 this is problematic and rather pointless since our battery temps correlate better to ambient than to engine compartment temp.

Now our alternators also do struggle a bit to generate at low rpms - lower idle on later cars didn't help - but the only way around this is either a higher idle (ECU), a different (crank) pulley ratio or a different/rebuilt alternator.

The remote (variable) regulator can mostly eliminate the temp compensation issue at very low cost - and get you more similar performance year round. It probably won't improve much over your winter results but will avoid the typical summer only troubles.

However set it to 13.8v - its the remote part that helps (not the variable)

Alan

Shark_Week

couldn't stop thinking about it so i double checked. alan is right. i have mine set up at 13.7 volts. not sure where i got 14 volts from? brain fart