Found the cure to our alternator woes!!!

[steve5575]

Our alternators are 130 amps!
I am underpinning it by 14%
A higher amp alt will add more windings to the case... making it hotter.

As predicted we are now seeing failures with the start-n-charge alts because they are starting to see some milage. I also predict we will see lots of threads in July with more failures.

You got it right when it comes to heat. TOO HOT TO TOUCH is an understatement. The small case does not allow for air to circulate. And its buried in the engine compartment. POOR DESIGN on the case and location.

Ive been thru 4 alts so far. They were all cooked inside. and all of them went in the summer. The guy who rebuilt my alt last time showed me the windings... looked like there was a fire inside the case.

You can buy an expensive 180amp (with all the best parts LOL) and underdriven it with a larger pulley and it wont help. NOT much!

Ive tried all the alts (not the start n charge until the results are in) and nothing will help to put the fire out inside the case.

The cure would be to relocate the alt and build a bigger case.

My start n charge took a dump about 3 months of DD use. Jamie took care of it no questions asked (well a few anyways). I asked him to install the pulley for me when I first purchased it because I didn't have the proper tools. The pulley some how came loose, shreaded the belt and ground into the case. Some how it lasted for 200 miles getting me home from Houston to Austin. That next morning I figured out what in the hell that sound was coming from.

Any how, Jamie was a stand up guy. Aside from the pulley, the bearings and everything worked great. 64k miles and on alt #4.

Edit: 03-15-2010 - Recent Start-n-charge action. When I sent Jamie back my bad alt I also included the shredded belt and the receipt from Autozone for the new Gatorback belt. I wasn't intending on this but he wrote me a check for the belt and mailed it to me. Now that is a true stand up guy. Who else does this?

 

[COBRA_ESQ]

Gotta love this place! Can't tell you the number of times I've read a thread where someone is having a problem of some type and usually somebody comes to the rescue with great info and advice. Here guys, have a beer on me. :beer:

QFT :banana:

 

[IronTerp]

Excellent writeup Bumpsticks! This subject has been debated for 8 years and this is by far the best explanantion that has been produced. :beer:

 

[TwinTurbo4vGT]

man ive never had a problem with my severely modded car. But then again i have a 240A alternator...

 

[VADEi2]

A guy in my area says he figured out the issue that he can upgrade my alternator by changing the resistor on the alternator! He then said rewiring it. I don't know the specifics but I'll try an post the link that he posted.

Ca-Mustangs.com forums

 

[BdaleCobra]

Great write up bro!

 

[black 10th vert]

I know a few guys have routed the hole next to the fog light to direct air onto the alternator, wonder if it does provide some help in cooling them off and making them last?

Aside from underdriving it like the op posted here, I think the air ducting is the next best thing to assist in keeping it cool given the poor engineering of it's placement. I definitely plan to do this later this season before my car goes back on the road.

 

[BUMPSTICKS]

Our alternators are 130 amps!
I am underpinning it by 14%
A higher amp alt will add more windings to the case... making it hotter.

As predicted we are now seeing failures with the start-n-charge alts because they are starting to see some milage. I also predict we will see lots of threads in July with more failures.

You got it right when it comes to heat. TOO HOT TO TOUCH is an understatement. The small case does not allow for air to circulate. And its buried in the engine compartment. POOR DESIGN on the case and location.

Ive been thru 4 alts so far. They were all cooked inside. and all of them went in the summer. The guy who rebuilt my alt last time showed me the windings... looked like there was a fire inside the case.

You can buy an expensive 180amp (with all the best parts LOL) and underdriven it with a larger pulley and it wont help. NOT much!

Ive tried all the alts (not the start n charge until the results are in) and nothing will help to put the fire out inside the case.

The cure would be to relocate the alt and build a bigger case.

First off, I know the stock alternators were 105-110 amps regardless of what they were rated at. After doing my own research and also speaking with quite a few alternator rebuilders they are actually NOT 130 amp units. Now the remaned ones you can buy from ford are now labeled 130 amp but I have yet to see one so I don't know for sure. Second, just because you up the amperage rating on the alternator does not mean its going to produce more heat. If you are not drawing all that amperage out of the alternator then it should stay relatively the same. Amperage rating is just a pool for the car to pull from, the alternator doesn't produce that amperage all the time. This is a common misconception.

In terms of Start N Charge, I have a sneaky suspicion that people are having problems with his units because they are being over spun. Perhaps the upgraded parts are much more affected by over spinning.

 

[03yellow]

I've purchased several Alts for from the local auto parts stores. If you get one from orilleys,autozone etc... they are all under 105 amps. I had each tested before trying to install. The only one who said theirs was 130amp was NAPA it tested 112 amps.

My stock Ford Alt tested at 131 amps. at the alt shop. My rebuilt tested 133 amps. My last Ford Replacement alt tested 132amps.

When you up the Amperage you add more windings inside the case. The windings block the air holes and vents in the alternator; holding in the heat. The case is too small!

Most people who mod their Cobras know to add a larger pulley. Start n charge has been pushing the larger pulleys to save the life of their Alts.

The issue is the Case is too small to rid the heat and the alt is surrounded by hot engine parts. Ive seen this before with Ford; once they added a fan onto rear of the alt; it used the pulley axle to spin the fan.

First off, I know the stock alternators were 105-110 amps regardless of what they were rated at. After doing my own research and also speaking with quite a few alternator rebuilders they are actually NOT 130 amp units. Now the remaned ones you can buy from ford are now labeled 130 amp but I have yet to see one so I don't know for sure. Second, just because you up the amperage rating on the alternator does not mean its going to produce more heat. If you are not drawing all that amperage out of the alternator then it should stay relatively the same. Amperage rating is just a pool for the car to pull from, the alternator doesn't produce that amperage all the time. This is a common misconception.

In terms of Start N Charge, I have a sneaky suspicion that people are having problems with his units because they are being over spun. Perhaps the upgraded parts are much more affected by over spinning.

 

[BUMPSTICKS]

I agree completely with you that the case is too small. Fact is, the cars are now too old and nobody is going to come out whit a bigger or "upgraded" case for us. It's time to work with what we got. We are undoubtedly overspinning our alternators in stock trim. This can cause a great amount of heat on its own! After slowing mine down it is not nearly as hot to the touch.

I agree the case is too small, but there's more to it than our windings are too big. Slowing these things down do a surprising amount of damage control.

 

[Saleen281sc]

1. The car, as built by Ford, is over spinning the alternator.

Through my year of testing more of our alternators than you could shake a stick at, I have found that the alternaotrs in our cars all turn on ( as in start producing voltage) at about 650-700 rpms. That is the speed of the alternator, NOT the engine speed. So, if the crank pulley is roughly 7.5 inches and the alternator pulley is around 2.5 inches, the alternator spins about 3x what the engine does. So on any given car with an idle speed of 800 rpms, the alternator is now spinning at 2,400 rpms

Not that it matters..but isn't this the case with every OEM alternator/engine combo out there?

I can't remember where I saw it, but I read that most OEM crankshaft pulley/alt pulley ratios are 3 to 1, and this is because modern alternators will not charge efficiently turning under 2400 rpms.

My 2010 GMC truck has a huge crankshaft pulley, and a tiny little alternator pulley- and I have the upgraded alternator at 230A.

I have no doubt the alternator is spinning 2-3 times what the crank pulley is spinning.



EDIT: AHA!..saw it in Super Chevy a while back. Heres an excerpt:


"Alternators must spin faster than the engine. The speed of the alternator is a function of the pulley ratio between the crankshaft and the alternator pulley. This ratio from the factory is usually 3:1, which means that the engine's crank pulley is three times the diameter of the alternator pulley. Stated another way, at 1,000-rpm engine speed, the factory alternator spins 3,000 times a minute. Alternator idle performance is proportional to the pulley ratio and the engine idle rpm. Because high output alternators have a very steep idle performance curve, it is critical that the alternator spin at a minimum of 2,400 rpm. If alternator rpm drops below 2,400, output capability will quickly decrease.While underdriving a vehicle's accessories can boost performance at higher engine RPM, it will sacrifice charging at idle. By keeping a small pulley on the alternator, 10 or more additional amps (at a given engine rpm) can be created. March Performance and others offer V-belt and serpentine drive pulleys that are as much as 15-percent smaller than original equipment. Using overdrive pulleys, as opposed to underdrive pulleys, will improve the charging system's performance, but keep in mind that it is recommended alternators operate below 18,000 rpm, so if your engine spends a lot of time past 6k, keep your pulley ratio lower than 3:1."

 

[BUMPSTICKS]

Well at the very end it recommends that alternators be operated below 18,000 rpms. Stock configuration on the cobras allows the alternator to spin to 19,500 and that's only if you shift at 6500. Some people shift above that. It also says that a ratio of less than 3-1 should be maintained if the alternator is routinely spun above 18,000.

Also, I'm not sure that this article is on computer controlled cars. This might be on chevy one wire alternators. That may make a difference in how everything works because a one wire is designed to run full on all the time.

 

[Saleen281sc]

Well at the very end it recommends that alternators be operated below 18,000 rpms. Stock configuration on the cobras allows the alternator to spin to 19,500 and that's only if you shift at 6500. Some people shift above that. It also says that a ratio of less than 3-1 should be maintained if the alternator is routinely spun above 18,000.

Also, I'm not sure that this article is on computer controlled cars. This might be on chevy one wire alternators. That may make a difference in how everything works because a one wire is designed to run full on all the time.

The article is dealing with 110a and above alternators, which is exactly what is on just about every car coming out of the factory for the last 10-12 years.

Also...I don't think it matters what rev the alternator is turning at 6500 engine RPM, since that RPM is not a sustained RPM. I would imagine a "normal" Cobra engine spends 99% of its time between idle and 3-4000 rpms on a DD.

To me, it looks like SVT went somewhere in the middle with the alternator RPMs, compromising between a smallish body, and the ability to keep the battery and electrical functions near peak performance.

One of the drawbacks of this small size obviously is the heat factor.

 

[03yellow]

Found the Cure:

QuikCool System Dual/Remote Rectifier Alternator System, Dual output Alternator, High Output Alternator, 200 Amp Alternator Upgrade kit

 

[CobraBob]

The fact that the Start 'N Charge High Performance alternator handles the electrical system better than the OEM alternator seems to say it is more than a heat issue. I'm sure that is part of it, though.

 

[VADEi2]

The fact that the Start 'N Charge High Performance alternator handles the electrical system better than the OEM alternator seems to say it is more than a heat issue. I'm sure that is part of it, though.

Did he have a website? I never could find it. :burn:

 

[BUMPSTICKS]

The fact that the Start 'N Charge High Performance alternator handles the electrical system better than the OEM alternator seems to say it is more than a heat issue. I'm sure that is part of it, though.

Exactly what I was thinking.

BTW, I posted this to help all the other members out, not to have a friggin debate. My alternator, as well as a few others I've tested, run perfect slowed down. I have also noticed a much lower temperature at the alternator. I don't really care what the article from chevy high performance, or the ford tech says. It works for me and it works better!

Guys do what you want with the research I've done. In the end it really has no effect on me at all. I just thought I'd give everyone a heads up.

 

[Teej281]

Would this work for other cars that arent Cobras...like say on a mustang GT???

 

[dan04gt]

Would this work for other cars that arent Cobras...like say on a mustang GT???

I haven't heard of any issues with the GT alts. failing, and if that is true it seems that the high revs may be the tipping point for repeated failures in cobras.

 

[03yellow]

This has been debated hundreds of times on here.

You said you found the "CURE" but people that have pullied cars with 180 amp alternators/ under spun / are still having failures. So much for the all those underspun 180-220 PA alts that failed years ago; and they had the best internal parts (guess they wernt fireproof)LOL.

When your alternator is getting hot enough to start a fire,reducing the temps by a few degrees with a higher amp alt and underspinning wont help.

The REAL test: put 35,000 miles on the alt with and upper and lower combo!

I purchased 4 alts so far, all underspun and one underspun PA-180 amp. the best was the ford 35,000 miles

I just purchased another new Ford Alt because they have the best longevity. With the 3.2 alt pulley it may last 35,000 miles.

I agree with your point 3. HEAT.

The real cure is relocating the alt and putting it in a larger case that can disperse the HEAT. Or find a way to cool the back of the alternator.

When your 180amp, start n charge, underspun alt fails at 35,000 miles; open it up and remove all the burnt and melted parts and post the research!


Your quote:
BTW, I posted this to help all the other members out, not to have a friggin debate. My alternator, as well as a few others I've tested, run perfect slowed down. I have also noticed a much lower temperature at the alternator. I don't really care what the article from chevy high performance, or the ford tech says. It works for me and it works better!

Guys do what you want with the research I've done. In the end it really has no effect on me at all. I just thought I'd give everyone a heads up.[/QUOTE]