Big 3 Wiring Upgrade & High output alternator

gmcman

Guru
Dec 12, 2011
4,526
Nice, I'm in the market for a new alternator as well for my 4.2, been going back and forth from 13.6-13.7V and dims at high RPM.

Looks like a beast!
 

TollKeeper

Platinum Donor
Dec 3, 2011
6,400
Brighton, CO
I wonder if that would make it so my truck quits eating batteries every 2 years.
 
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gmcman

Guru
Dec 12, 2011
4,526
@NODAYSOFF Reading up a little on these alternators, did yours come with a smaller pulley? If so, did the stock belt and tensioner work or did you need a shorter belt?
 
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NODAYSOFF

NODAYSOFF

Registered Member
Original poster
Jul 16, 2020
11
Lansing Michigan
@NODAYSOFF Reading up a little on these alternators, did yours come with a smaller pulley? If so, did the stock belt and tensioner work or did you need a shorter belt?
Nope, came with factory size pulley, and a factory belt still works with it also, just had to get the 4 to 2 wire pig tail adapter so the battery light wouldnt get tripped, other then that pretty simple install.
 
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gmcman

Guru
Dec 12, 2011
4,526
I looked at those a few months back, put it on hold but now back in the market. I called them and asked if they offered a stock size pulley for the 4.2 and they said no, only undersize.

With regards to your 5.3, the stock pulley might be smaller but I would double check. Apparently if it reads "Mechman" on the pulley then it's undersize, and your tensioner would likely make up the difference in regards to slack, but not tension. Just throwing that out there in case you may have a belt that might slip.

With the 4.2 application, the 5,000 RPM limit is due to the 16,000 RPM design speed of the armature, and would likely be near 20K RPM @ 6000 RPM engine speed.

May have to rethink this.
 
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NODAYSOFF

NODAYSOFF

Registered Member
Original poster
Jul 16, 2020
11
Lansing Michigan
I looked at those a few months back, put it on hold but now back in the market. I called them and asked if they offered a stock size pulley for the 4.2 and they said no, only undersize.

With regards to your 5.3, the stock pulley might be smaller but I would double check. Apparently if it reads "Mechman" on the pulley then it's undersize, and your tensioner would likely make up the difference in regards to slack, but not tension. Just throwing that out there in case you may have a belt that might slip.

With the 4.2 application, the 5,000 RPM limit is due to the 16,000 RPM design speed of the armature, and would likely be near 20K RPM @ 6000 RPM engine speed.

May have to rethink this.
No issues so far, put 1k miles on it since install
 

gmcman

Guru
Dec 12, 2011
4,526
No issues so far, put 1k miles on it since install

I guess the only issue you may encounter is IF the pulley of your new alternator is SMALLER than the stock. According to them, the armature has been known to break the ends of the wires above 16,000 RPM, which is why they noted the 5,000 RPM limit.

Again, that was for my application, the question is if your pulley is smaller than stock, if not, then no worries.

The tensioner will adjust to a given point, but can lose it's rated tension when near the end of it's travel.

If the pulleys under a good load aren't too hot to touch you should be fine.

The point of my ramblings, a buddy of mine was going on a 900 plus mile road trip and he wanted to change his serpentine belt. I told him to get it from the dealer that way he knows it's the correct size but he picked it up at a local parts store.

Couple days driving to work was fine, then the weekend on the trip they called me and said they were hearing a squeal. I said pull over to the next service station and have them put on the old belt that I left in the rear of the vehicle.

They didn't change it and ended up on the side of the road losing either the water pump or the alternator from heat, and had to get a 50 mile tow and a hotel room for the night.

Just looking out.
 
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NODAYSOFF

NODAYSOFF

Registered Member
Original poster
Jul 16, 2020
11
Lansing Michigan
I guess the only issue you may encounter is IF the pulley of your new alternator is SMALLER than the stock. According to them, the armature has been known to break the ends of the wires above 16,000 RPM, which is why they noted the 5,000 RPM limit.

Again, that was for my application, the question is if your pulley is smaller than stock, if not, then no worries.

The tensioner will adjust to a given point, but can lose it's rated tension when near the end of it's travel.

If the pulleys under a good load aren't too hot to touch you should be fine.

The point of my ramblings, a buddy of mine was going on a 900 plus mile road trip and he wanted to change his serpentine belt. I told him to get it from the dealer that way he knows it's the correct size but he picked it up at a local parts store.

Couple days driving to work was fine, then the weekend on the trip they called me and said they were hearing a squeal. I said pull over to the next service station and have them put on the old belt that I left in the rear of the vehicle.

They didn't change it and ended up on the side of the road losing either the water pump or the alternator from heat, and had to get a 50 mile tow and a hotel room for the night.

Just looking out.
Just measured old pulley, new one seems to be the same size. Thanks for the input I appreciate it.
 

xavierny25

Platinum Donor
Mar 16, 2014
6,109
Staten Island, N.Y
@NODAYSOFF I'm curious now, I'm sure you didn't go that big with an alternator and red top battery and those huge battery distribution lugs just because your window switch was dimming the lights. There's got to be a burp box in the trunk or some sort of off the wall build in there somewhere.
 

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