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Voltage Problem Finally Fixed

Zack

4 Doors 4 Life
Mar 21, 2004
6,297
20
NW Indiana
Finally got a chance to spend some time with the Cobra again last night.

On the dyno (and street) my Voltage was dropping down to 12.3-12.5 at WOT, causing the MAF Counts to drop for a brief moment. This obviously made the car difficult to tune at that rpm.

Mind you the car has a new NAPA (most expensive) Alternator on it and is advertised as being 130a. Aside from cleaning all connections, I added a PA Performance Wire upgrade kit, Ran an additional 6ga ground wire from the engine block directly to the negative terminal on the battery, Made a very crude heat shield to place between the drivers side header and the alternator, then ran a 3" flexible drier duct from the Drivers side hole next to the foglight all the way to the back of the alternator.

BINGO. I logged it a few times on the way to work and voltage stays at or above 13.1 volts at 6k+rpms. Cruising around the voltage is now 13.8-14.2, where before it would start at about 13.7 and steadily drop to around 13.3-13.4 as the engine compartment heated up.

Im quite relieved its fixed! :clap:
 

Zack

4 Doors 4 Life
Mar 21, 2004
6,297
20
NW Indiana
now it's time to uninstall all the pieces one at a time to see which one actually fixed it.
I'm guessing the new cable to ground.

Funny, as I was making my original post, I just KNEW you would be the one to ask that! :biggthump

Im relieved, because now I bought some time to make a dual alternator bracket in preperation of the Killer Chiller. :headbang:
 

Dana

Bluesmobile
Mar 2, 2004
2,619
0
Funny, as I was making my original post, I just KNEW you would be the one to ask that! :biggthump

Im relieved, because now I bought some time to make a dual alternator bracket in preperation of the Killer Chiller. :headbang:

two alts is going to be a real issue to set up and dial in.
Alignment is really critical on them.
Especially since you found and corrected the problem.
 

Dana

Bluesmobile
Mar 2, 2004
2,619
0
IF you insist on doing this, then consider setting up the pulleys so that one is virtually inactive at lower RPMs and comes on as the engine gets into the upper ranges.
Doing this can avoid overspining and still have both low and high RPM performance
 

Zack

4 Doors 4 Life
Mar 21, 2004
6,297
20
NW Indiana
IF you insist on doing this, then consider setting up the pulleys so that one is virtually inactive at lower RPMs and comes on as the engine gets into the upper ranges.
Doing this can avoid overspining and still have both low and high RPM performance

I dont agree. With both Alternators running all the time, the demand on both will be split, the independent amperage demand will be less, and in turn will make less heat, which means more amps/voltage.
 

Dana

Bluesmobile
Mar 2, 2004
2,619
0
low output isn't the issue, assuming the charging system is functioning correctly.
130 amp capacity is more than enough to power the car.
over spinning and excessive engine heat are the two issues that have to be dealt with.

by slowing them both down, one more so than the other, you are not pushing either one into an overspeed condition but still obtain high RPM output.

This also avoids higher than desired heat output from the alternator.
A side note: A second alternator is going to introduce more unwanted heat into an already overly warm underhood environment.
 
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