How to hook up Carl's new alternator?
07-09-2008, 10:10 AM
#16
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It won't make a jot of difference to the performence at idle - only to the actual regulated voltage at higher rpms. It may make a difference to the regulated voltage when the battery is depleted and the alternator is charging it at elevated current. I'm sure it would only make mV of difference - much less than the typical drop you will get at idle...
I have mentioned before my concern on these high power alternators. In evaluating thier specs I found several that can output over 50% more current than the stock alt output at > 3000rpm using the same basic bosch chassis.. (or std delco) however all the ones I could find specs on actually output less than the stock bosch alternator at low (idle) rpm. To me that is a pointless & entirely useless trade-off.
I'd love to have someone prove they have an alternator that can produce 50% more current at engine idle rpms - I'd buy one. Build an alternator and test it at engine idle rpm (ratioed to the alternator rpm based on the stock crank pulley and actual alternator pulley).
I'm happy to pay top dollar for this - but I want to see proof its much better at idle... I have yet to find anyone who is willing to build it and measure it & document it to prove it out...
Alan
I have mentioned before my concern on these high power alternators. In evaluating thier specs I found several that can output over 50% more current than the stock alt output at > 3000rpm using the same basic bosch chassis.. (or std delco) however all the ones I could find specs on actually output less than the stock bosch alternator at low (idle) rpm. To me that is a pointless & entirely useless trade-off.
I'd love to have someone prove they have an alternator that can produce 50% more current at engine idle rpms - I'd buy one. Build an alternator and test it at engine idle rpm (ratioed to the alternator rpm based on the stock crank pulley and actual alternator pulley).
I'm happy to pay top dollar for this - but I want to see proof its much better at idle... I have yet to find anyone who is willing to build it and measure it & document it to prove it out...
Alan
I plan to add another wire from alt output stud to jump post, and a separate ground from alt case to chassis ground. Are there other cables which should be augmented for better performance?
Thanks,
07-09-2008, 11:20 PM
#17
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Been through a few alternator iterations, the French POS that was on it stock, then a Bosch...although I had hoped for more improvement at idle than I have, it is dramatically better than stock which never read above 11V on the gauge at idle, this one is above 12 with A/C and headlights on. Again I don't have a good grasp of the gauge accuracy, it is all relative to me and from that perspective the improvement is obvious.
07-10-2008, 12:40 AM
#19
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I really don't think Porsche did a fantastic job of the main power wiring in the car - they did some rather oddball things.
One worthy of fixing is to replace the 2 red feeders from the jump post to the top of the CE panel with something much bigger - however through the firewall this is a vary hard task to do without creating new risks...
These undersized and split feeders seem very stupid ideas to me...
The cooling fans also deserve to be fed from the alternator direct rather than the current circuitous feeder path through the car unfused direct from the battery... again a stupid stupid idea. But then you need relocated (& bigger ATX) fuses for these.
The B team strikes again...
Alan
07-14-2008, 08:32 PM
#20
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Well, I finally got my alternator. It came directly from Mechman, and included a custom bracket for the tension adjuster. I put in new accessory belts. I had a little trouble getting the alternator belt tight until I figured out how the tensioner works. I'm sure it's just my inexperience. I added additional cables to the starter terminal and the jump post, and added another engine to chassis ground cable.
Anyway, It runs fine, new Porkensioner and all, The voltage runs about 2.5volts higher on the gauge than it did before. I haven't measured at the battery or the jump post so I don't know an absolute voltage value. The relative improvement it very nice though: low beam headlights, A/C w/blower on speed 4, brake lights on and turn signal on, 850 RPM idle speed; before 10 volts +/-, after Carl's alternator 12.5 volts +/-.
I'll give follow-up info in a week or two. Overall I am initially very pleased.
Anyway, It runs fine, new Porkensioner and all, The voltage runs about 2.5volts higher on the gauge than it did before. I haven't measured at the battery or the jump post so I don't know an absolute voltage value. The relative improvement it very nice though: low beam headlights, A/C w/blower on speed 4, brake lights on and turn signal on, 850 RPM idle speed; before 10 volts +/-, after Carl's alternator 12.5 volts +/-.
I'll give follow-up info in a week or two. Overall I am initially very pleased.
