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Spoke with the guys at power master and gave their 160A alt a try.
My experience wasn't much better. Installed the 3" pulley. (which is really 2.95" going by the area the belt rides on) It had a label on it stating it was regulated to 14.8. I assumed it meant it would charge at 14.8 if needed. It charges at 14.1 for idle and cruise. I did see 14.2 at one point. The old alt would charge at 14.6+ cruising and at idle with the same pulley. On low boost I made 5 pulls and voltage held at 13.1. Not the greatest but I guess it's working ok. I turned the boost up and it leaned out again. Voltage dropped to the 11's. So maybe it is belt slip. I ordered the billet ICT manual tensioner to try. But even when not slipping the power master didn't hold a 14+ to red line, which is a bummer. I also don't have the goofy monster amp draw from my Ford Taurus fan anymore. So the draw on the system should be very little. I noticed a .4 voltage drop from the back of the alt stud to the battery term in the trunk. So I'll add another "0 gauge" wire form the alt to the BAT. IDK what else to do. Hope you have better luck!
I have checked at the alternator and it's only a .3 diff at idle and a .4 difference at RPM. The battery POS term. and "bus" that I power all the electronics from reads the same. In the mega squirt manual it suggests you wire the main bus to the actual battery terminal for voltage stability I assume? I have done this.
I basically run 1 gauge form the alt to a large positive lug in the tire well. There I tie in the factory harness positive leads, starter, and a long 2 gauge wire going to the battery in the trunk. Then a 4 gauge from the battery to the bus bar in the glove box powering my ECU and injectors/IGN. Only oddball variable was I used aluminum wire. I had a ton of old salvage from aircraft and figured it would be little lighter weight.
I just want to rule out everything but the alternator at this point, as I don't understand why some have issues and others don't.
I'm told that MECHMAN states their alternators will charge to 8k+ RPM on the factory pulley sizes without issue. Members here reporting 14.2v at over 7k on factory pulleys. May buy one of those for the other car just to compare.
Where are you measuring voltage at high rpm? ECU? Fuel pump? Alt? Bat? Would be interesting to measure V drop through the wire at rpm.
The ECU during pulls from the data logger. Also my PLX multi gauge from the main bus behind the dash. It mirrors the ECU readings. The alt term w/ my fluke meter at idle and at 4000rpm or so. I can check off the back of the alt directly with a meter and try to watch during a pull. I ordered a 20' set of 0 gauge jumper cables for $32. Figure I'll leave the wiring that's there and overkill it with another heavy gauge wire so the alt. companies can't say I don't have it wired properly. May just leave the cables together and run a ground wire the length of the car from ALT. mounting plate to NEG battery post too. What can it hurt?
You shouldn't need the wire from the alt ground to the back as long as the block to the battery/chassis is sufficient.
PS...now that I think about it its REALLY not a good idea. The inductance of the wire will not be good for surges in current when there is an increased demand.
You shouldn't need the wire from the alt ground to the back as long as the block to the battery/chassis is sufficient.
This. If the battery terminal runs to the frame, make sure you have sufficient ground from the frame to the engine. Remember, the starter and alternator are grounded to the block, so you need to make sure the block hag good ground from the frame and also make sure the spots on the block where they are mounted are not painted.
This. If the battery terminal runs to the frame, make sure you have sufficient ground from the frame to the engine. Remember, the starter and alternator are grounded to the block, so you need to make sure the block hag good ground from the frame and also make sure the spots on the block where they are mounted are not painted.
I will go a step further and say you must have a ig gauge wire from the battery ground directly to the engine block.
I have a ton of grounds from chassis to engine. At least 4, 2 of which are 1 gauge. And a few of the braided factory ground straps. Neg term is zero gauge thats about 6" long from the bat negative to the chassis. I have 2 300A breakers in parallel at the ground. and a 300A inline fuse on the POS side. Really don't feel like it's "under wired". Can't imagine it's pulling much load either. 2 7amp fans that shut off at wot, 1 AEM 380, a voltage booster, water inj pump, and the ECU/IGN.
I'm certainly not an expert in ground loops, but have done electronics and cars for 50 years.
IMHO ground loops are caused when you have marginal ground connections and a significant amount of current therefore finds a lower resistance path through an unintended (and low capacity) connection. If all ground wires in a car are never above 0.1 Volts over true battery ground, I doubt you will ever have problems.
To me than means a 0 gauge from battery to frame, 0 gauge from frame to engine, 4 gauge from frame to chassis, 4 gauge from engine to alternate chassis point and then 8 gauge from primary chassis point to other chassis points such as where the fans and headlights connect, especially chassis sections not welded to the main chassis.
ddnspider is welcome to correct me and I will defer to his expert opinion.
Mrvedit hits some good points. If you look at the grounding schemes for lightning protection there is almost always more than 1 grounding point. If you look at electrical design of a data acquisition unit, there is almost always more than 1 return path. Using a single ground point is typically more theoretical than practical. Since the real world is not ideal, having a single ground can cause problems.
As a crazy example, imagine 2 currents both looking to return to the source. They can either take a 1 foot straight path to the source, or a long 5 foot loop. Some currents prefer the 1 foot path and other currents actually prefer the 5 foot loop. It doesn't want to go through the 1 foot straight path. Now if the 5 foot loop wasn't provided, you'd probably end up with a ground loop because the current would be trying to return through an unintended path. Electronics can be fun.
07-13-2020, 07:44 AM
