Thread: The alt rewire mod actually DOES increase fuel mileage!!

First, current only travels on the outside of the wire, in high frequency situations, it is known as the skin effect. Secondly, what is the point of installing the re-wire if you are still going to divert some of the current around the higher resistance, longer wire?

Additionally, I never said the install wasnt fine, I said it seemed pointless. I admitted that it would work and that the current going over the secondary OEM connection would not be that much, but why send it there in the first place.

Easyperformance advises you to leave the OEM wire installed. I'm guessing that is why he has both wires.

"Note: We recommend leaving all original alternator and fuse box wiring attached." -Easyperformance.com

Originally Posted by SyntheticShield

Well you got two paths now to the fuse block from the alternator. True, it will for the most part, take the path of least resistance, so the vast majority will be carried by the alt. re-wire run, but you still have some going across that original wire thats considerably smaller and pushing about 8' in length.

From just purely an electrical standpoint, Id want all the power going across the one wire. Unless you're keeping the stock wire in there for back up, and at that point if that is the case, why not install two alt. rewires?

I get you now Scotty! My big question, kind of inline with Lee's would be, how do I go about fishing this 8' wire out of my engine? If it is a problem, all be it a small one, could I just not remove the smaller wire thus eliminating the 2 wire theory then? Or is the factory alt wire hooked to other things before it reaches the fuse box?

Originally Posted by GreenNirvana101

Easyperformance advises you to leave the OEM wire installed. I'm guessing that is why he has both wires.

"Note: We recommend leaving all original alternator and fuse box wiring attached." -Easyperformance.com

LOL guess I should have read this before posting my above comment

Thanks Green!

I am purchasing two more alt rewire kits from Adam and I will be able to finish my "big 3" wiring setup. Then we will see how efficient it truly is

Originally Posted by GeddyLee

I get you now Scotty! My big question, kind of inline with Lee's would be, how do I go about fishing this 8' wire out of my engine? If it is a problem, all be it a small one, could I just not remove the smaller wire thus eliminating the 2 wire theory then? Or is the factory alt wire hooked to other things before it reaches the fuse box?

You dont. It runs from the alternator, towards the drivers side, through that harness that runs over the blower, then it goes to the front of the engine bay then back to the passenger side then back up to the fuse box. It is running about 8 - 10' to make essentially a 2' run. But that wire is taped in the harness, so you wont be fishing it out without opening up the harness and taking out the tape that is loosely wrapped around it.

What I did with mine is just disconnected it on both ends, taped up the connector so it would not short out against anything then secured it so it would not be flopping around. But I have always planned that once I had to do any major work, such as I am now, that I would take the time to pull that wire out of the harness.

That wire is not hooked to anything else, it goes straight (albeit the long way) from the alternator to the fuse box. I used an multi-meter to check that when I pulled mine. I suppose if one wanted to fish it out of the harness it could be done, but its going to be no easy or quickly done task.

Now, that all said, I want to restate, there is nothing wrong with leaving it hooked up, but as I mentioned it seems pointless to me to do so. Although the current that would run through the OEM wires vs. the new alt. rewire is small in comparison, it is still some measurable amount.

Think of it like this. You take your garden hose and want to hook up to a Y connection. One side of the Y is a 3" pipe, the other side is a 1/4" pipe. While the vast majority of the water is going to take the path of least resistance through the 3" pipe, there is still some diverted to through the 1/4" pipe. In this case, the 1/4" pipe is the OEM alternator wire. What gets diverted around that wire is significantly reduced by the time it gets to the fuse box because of the resistance of the wire.

If you do the math on the resistance of that wire from the alternator with the current you can push with the alternator, you'll see that you can drop about 1 - 1.5 volts across that wire. So why leave it in there with the alternator re-wire. If you are going through the trouble, however little it may be, to install the alternator re-wire, then disconnect the OEM wire and get the full benefits of the re-wire, not 98%.

Anyway, just my thoughts on it. Ive done the math on it and if Im going to modify something then I want maximum results from the work.

Has anyone measured the volts?
1. OEM Wire only
2. OEM and Rewire connected
3. Rewire only

That would probably put the best perspective on things...

I haven't done the rewire yet, but I hope to order the rewire and voltage booster by the end of the month.

No, but that would probably be a good thing to do, as well measure the current through the two. I know that, mathematically, if you are pushing the limits of the the fuel pump, that wire and its associated voltage drop can become significant.

Originally Posted by SyntheticShield

First, current only travels on the outside of the wire, in high frequency situations, it is known as the skin effect. Secondly, what is the point of installing the re-wire if you are still going to divert some of the current around the higher resistance, longer wire?

Additionally, I never said the install wasnt fine, I said it seemed pointless. I admitted that it would work and that the current going over the secondary OEM connection would not be that much, but why send it there in the first place.

This is was my understanding, but I've been out of college since 81 so perhaps things have changed.

Flow differences

since the install of the alt. rewire and stage 1 volt booster i have notice a .4 miles per gallon increase in gas mileage . i will post up after my next fill up to let you know if it changes any .

I installed the rewire and the stage 1 booster as well... today I filled up to find the actual mileage... +1.2 mpg increase. Not bad at all! Especially at $4.05 a gallon!

Originally Posted by yourTVlies

Hey all -

I don't mean to resurrect this thread without warrant - but I was thinking about doing the alt rewire for kicks (and an increase on fuel economy if I'm lucky). And I was curious about the the necessity for fusing this. I've done some searches and it seems as though some folks have been a bit concerned over this - but if my line of thinking is correct - an additional fuse on the rewire shouldn't be needed, as the stock wire doesn't have a fuse either - correct?

Thanks.

Unless I looked at my GM manual incorrectly this "alt rewire" does bypass a fusible link. fwiw, I still have mine installed w/o a fuse, but have a feeling it's not the smartest thing.

There was someone on here that came up with a way of fusing the alt rewire but I dont recall who it was or what thread it was in.

Ive ran mine from day one with no fusible link or any type of fuse or circuit breaker for that matter.

I don't see where the issue is. All of your systems have fuses in line, so you're not putting anything in danger but your alternator. And even then, it's only if the wire falls off and shorts to ground that you're in trouble. I don't see that happening.

You are correct in that. However, the closer the fuse or what ever electrical interrupter is used, the better. There is a fusible link in the OEM alternator wire, so while I know of no issues in using the alternator re-wire, it would make sense to have some protection there if it could be sensibly worked in.

^^Just use a 100amp in-line stereo fuse ?? they are pretty cheap

Originally Posted by yourTVlies

Interesting indeed. I may put one together and install it in a couple of days.

I've been logging my mileage pretty well since I got the car in June (topping off the tank, saving receipts, noting the miles per tank, and noting any driving habits).
The rewire seems like the easiest mod to potentially up the fuel economy of the rig.

You'll see a lot of haters when you mention the alt re-wire and any fuel mileage increases. But Ive done similar re-wires on three vehicles now and I am VERY anal about tracking my fuel economy. Im like you in that I save my receipts, the tank is topped off until it cant take no more and I write down the trip odometer and main odometer at each tank and reset the trip odometer at each tank and then I manually calculate the mileage and I keep a log.

Its only three vehicles so far, but I have yet to see one that did not benefit from using better or larger wiring than the OEM set up.