Just bought a powermax 250 amp ALT, Need overdrive pulley?

[Devan]

I just bought a new powermax 250 amp alternator off ebay from seller powermaxusa. When my rpms drop below 900 my voltage drops off. I tested the regulator on the alternator and it checked out fine. I figured going with a smaller pulley would fix this issue but why wouldn't this be addressed during manufacturing or why wouldn't they equip it with a slightly smaller pulley.

So I messaged the seller and he said "you need overdrive small pulley. with original pulley you get low output in idle that is why you need high amp gel battery the higher power you go you loss power in low RPM you need minimum 900RPM in idle or get smaller pulley ,Thanks"

I had a 200 amp alternator before this and had no problems. Has anybody else ever bought a 250 amp or higher alternator and had this same experience?

Wellll anyways im looking at getting an overdrive pulley and im hoping you guys could tell me if you think it will fit. I did check out the measurement specs like bore and center hub to first groove with my micrometer and they look to be right. Here are 2 links to the same pulley. Both pages combine tell you all the measurements you need to know.
https://www.summitracing.com/parts/pwm-115/overview/
https://www.cjponyparts.com/powermaster-alternator-overdrive-pulley-serpentine-1986-2004/p/ALTP15/


they say the inner diameter of where the groves are is 49mm, on my pulley its about 56-57mm
CJ say its .28 inch from center hub to first groove, thats right on the money
Summit says the bore is .664, on my pulley its about .669-.670. my alternator shaft at the smallest point is .666
my pulley is 6 groove

Im pretty confident this pulley will fit what do you guys think? Also has anybody had similar experiences with 250 amp and above alternators where the voltage drops off below 900 rpm? Im sure guys that have installed an underdrive crank pulley may have had similar problems however i am not referring to that although if you guys can find me an overdrive pulley for my application that is black i would be eternally grateful. I painted the alternator black and it has a nice matching black pulley on it. If I ended up getting one of those yellow cadmium pulleys ill prolly paint it to match the alternator i spent alot of time painting but i wont paint the belt groves

 

[Devan]

powermaster 115 did not fit. heres why

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[CDW6212R]

Sorry to hear some alternators creating problems. I've always thought a high amp alternator was based on making much more current it idle, not high rpm. The two I bought were 170 and 200 amps, and both were better than stock at idle, using the stock pulleys.

I was not impressed later when one went out and my local shops said it was not special other than the windings to make more power(the rest was typical stock parts). These 4G alternators do not have aftermarket support in the way of upgrade components. Everything available for them is stock level stuff, except for the main windings, which determines the power potential. 3G alternators have many aftermarket options though, better diodes etc.

Good luck with your alternator, there is one that Summit carries that has good reviews, and Tim here has on his 347 Sport. It's abut $250 and similar power.

 

[Devan]

When you refer to Tim, are you talking about vroomzoomboom? The guy with the stroked and blown 5.0?

O and unfortunatly i had already painted the alternator before i tested it lol. I worked at a ford dealership for 3 yrs till just recently and i should have definatly known to test my part before painting it. So I would like to try and make this work unless somebody wants to buy it for a reasonable price. its got like 6 or 7 coats of black and 3 or 4 clears lmao

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20171201_062119

• Devan
• December 6, 2017

 

[vroomzoomboom]

this is the one i both myself, and member dono bought

https://www.summitracing.com/int/parts/tff-7787c

 

[Devan]

ah Tim there you are, wow that alternator is perfect I wish i knew about that before I purchased this one. I did only pay 140 for it but thats what I get for trying to go cheap I guess. I had a 200 amp alternator in the truck originally and I knew the rear bearing was going bad for a long time i was just trying to ride it until it wouldnt work nomore. Finally when it started acting up real bad I bought an autozone 130amp alt to keep with me in case i got stuck on the side of the road while I ordered my 250 amp. well I ended up having to put the autozone 130 amp alt in when the rear bearing seal popped off and the ball bearing holders broke and flew into the brushes lol and hopefully I can get the alternator I painted working or get another one. I have a guy that might make a custom pulley for me. I cannot find an overdrive pulley for this 4G anywhere its getting on my nerves I been searching for a few days now. If I cant get the alternator I painted up running soon (I only have 90 days to return the autozone 130 amp) with an overdrive pulley Im gonna try to send it back to them and Im definatly gonna buy that tuff stuff alternator you suggested w/o a doubt.

Also I think I remember reading somewhere on here that a 99 and later taurus might have an alternator pulley similar to what Im looking for. Can anybody confirm that?

Last night I was reading your supercharged 5.0 true fire thread from like 11 to 5 in the morning and i didnt even get half way thru it. Well built machine you got there and im gonna prolly do the same thing although I did wanna thro a 4.6 SOHC in it I wish I could fit a DOHC but the 60 degree 5.0 seems to be the way to go, easier to work on, parts are cheaper and easier to come by and the swap is overall just easier. Im gonna wait till i dont have to put mine through inspection tho. In the meantime I am preparing to throw a cobra M112 on it. And i have alot of body work to do which reminds me to ask you what brand is that spoiler on your XPLR?

 

[fastpakr]

Satisfying my curiosity here - what are you running that requires more than 130 amps?

 

[Devan]

90 percent of that is my wiring and that's an older pic, theirs more wiring in there now and it looks a little neater then that and I also have 2 wall outlets in the vehicle. You can see from my avatar what my gauge situation is and imagine how many modules and how much power that takes.

20170626_050955

• Devan
• December 7, 2017

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• Devan
• December 7, 2017

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• Devan
• December 7, 2017

I also have some pretty serious twin fans on my Saleen F150 heat exchanger and a pretty good I/C system pump

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• Devan
• December 7, 2017

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• Devan
• December 7, 2017

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• Devan
• December 7, 2017

Then their is also the hidden meth injection system

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• Devan
• December 7, 2017

And theres a bunch of other stuff in the truck. might end up putting a 25-35 inch fold out flat screen in the trunk for tailgating kind of. I also just installed a front mount receiver hitch for a power angling custom Meyer home plow I just bought.

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• Devan
• December 7, 2017

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• Devan
• December 7, 2017

 

[Devan]

Might as well throw these pics out there for ya as well

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• Devan
• December 7, 2017

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• Devan
• December 7, 2017
• 2

 

[CDW6212R]

Cool, another blown V6 truck, and IC'd too.

I like the heat exchanger, that looks like a good alternative to mounting one behind the bumper. I've got a Super Duty trans cooler to place low and across the center support area. The space forward of that will get tight when I get to the IC parts.

 

[Devan]

I ended up finding a 48mm pulley just what i needed, the original was a 58mm pulley. However im still having problems at idle. The guy i bought the alternator from offered to give me an overdrive pulley even smaller then tht. He said it was 44mm. even if i had that 44mm pulley i think i would still be havin this voltage droppin at ide problem. If I'm at a red light and I have my climate control on and my subwoofers are hitting and I've got all my lights on that voltage drops down to like 10 volts that's unacceptable especially for a 250 amp alternator terrible product never buy anything from PowerMax USA. Ive decided im gonna go with that tuff stuff 225 amp alternator that vroomzoomboom told me about it just sux i already purchased 2 other alternators and two different pulleys which I was able to return one of them already and I'll probably keep the second one and maybe put it on the new alternator from Tuff Stuff on Summit. Hopefully I'll be able to return one of the alternators to AutoZone and hopefully I'll be able to return the one I painted back to eBay. I even modified a couple things on my belt drive to change one of the 90mm Ford idlers to a 100mm metco idler to make up for the slack on the Belt from switching from a 58 mm to a 48 mm alternator pulley

Lol let this also be a lesson to everybody test your stuff before you modify it if possible

 

[CDW6212R]

Thanks for your efforts. Posting the results of changes does help others, and we appreciate it.

 

[Devan]

this is the one i both myself, and member dono bought

https://www.summitracing.com/int/parts/tff-7787c

Hey VroomZoomBoom how is the alternator voltage on this 225 amp tuff stuff at idle with a factory sized pulley? Does it stay above 13 volts when your at a red light on the brakes in gear at say about 650 rpm?

This guy I bought the 250 amp alternator from keeps emphasizing that 250 amp and above alternators sacrifice idle voltage and that you need a high amp gel battery. I believe that with the way the PowerMaxUSA alternator (that Im currently using) is designed even if you had a high amp gel battery this alternator would tax that gel battery at idle and wear it out sooner then it should be even with a 44mm overdrive. I think what it really comes down to is that this alternator wasnt designed properly nor was it designed for the Ford 4.0 meaning the alternator pulley to crank pulley ratio for the ford 4.0 was not taken into account when it was made. Now Im really curious if people with 250 amp and above alternators have idle voltage problems. But I would imagine that has to do with the vehicle belt drive design and the design of the alternator and pulley ratio.

 

[vroomzoomboom]

mine stays above 13v. however, i dont have a stock pulley on it, and i also dont have a stock sized crank pulley on it. i also have changed a lot of electronic items on the truck

 

[Dono]

My stuff stuff alternator is not strong at idle with headlights, fans on, seats heating, etc. I'm using the pulley it came with, and I think it's the same size as my factory one.
So much changed in our trucks it's difficult to say if it would be ok for you at idle. Tim and I just adjusted our neutral and drive idles so we had a happy medium of isle quality, charging, etc.

If we could answer your question directly with certainty we would.

 

[Devan]

mine stays above 13v. however, i dont have a stock pulley on it, and i also dont have a stock sized crank pulley on it. i also have changed a lot of electronic items on the truck

My stuff stuff alternator is not strong at idle with headlights, fans on, seats heating, etc. I'm using the pulley it came with, and I think it's the same size as my factory one.
So much changed in our trucks it's difficult to say if it would be ok for you at idle. Tim and I just adjusted our neutral and drive idles so we had a happy medium of isle quality, charging, etc.

If we could answer your question directly with certainty we would.

I just installed the tuff stuff 225 about a week ago and it is dropping voltage at idle but nowhere near like the powermax 250 amp was. I did increase my drive and neutral idles by about 100 rpm and its not as bad. But once i install my 48mm pulley it should be perfect, the 100 rpm idle adjustment ive made should be fine, if not i dont forsee having to adjust idle that much more.
Vroomzoomboom you said u dont have a stock alt or crank pulley. What size is your alt pulley and what size is your underdrive crank pulley and what size is the stock crank pulley. I would like to get an underdrive crank pulley but with this alternator even having a 48mm overdrive im afraid id have to set the idle to high to compensate for the underdrive crank pulley. O waiitt thas right your 5.0 duhh dam the answers to those questions wont help me out based on your 5.0 will they. well they might if your 5.0 stock crank pulley is the same size as the 4.0

Dono here is a link to an overdrive alternator pulley
Ford 3G 6G Alternator 1.8" 6 Groove Overdrive Pulley Increase Amp At Idle | eBay
It took me over a week to search the web for this and i actually ordered another one at first that was wrong. The rear bore on this one is slightly longer and i thought that i was gonna have to trim it down but when i installed it, it actually brought my belt into a better alignment then the stock alt pulley. But you are also v8 as well jeees i gotta build the hell out of a 5.0 and do the swap already with my stage 8 ported m112.
I did have to grind down one spot on the alternator casing like i usually do so that one of my dual idlers can spin freely otherwise it would be stuck on the alternator casing. Im gonna try and post some shots.

I was only able to upload 1 picture it says ive reached my 75 mb limit. Do I have to delete pictures or something?

20180110_152620_001

• Devan
• January 15, 2018

 

[vroomzoomboom]

cant remember what a 4L crank pulley is stock. the alt i believe is 3 inch. i would look, but its too cold and the truck is covered in snow. the crank is either 7, or 7 1/4. not under driven, but over driven to speed up the supercharger.
btw, if you never use the m112 you have, i know i can find a home for it very easy.

 

[CDW6212R]

The stock 4.0 and 5.0 crank pulleys are almost identical, about 6" diameter. The one underdrive 4.0 balancer was over $250, and it's not really much smaller, about 1/2" I'm guessing. I have those since my 99 is still a V6.

I'm also going to a 7" crank pulley for my V8, so the alternator will be helped by that. Thanks for posting this detailed review of the alternators, having proper running current is way important. This helps a lot, and others will appreciate it too.

 

[Devan]

cant remember what a 4L crank pulley is stock. the alt i believe is 3 inch. i would look, but its too cold and the truck is covered in snow. the crank is either 7, or 7 1/4. not under driven, but over driven to speed up the supercharger.
btw, if you never use the m112 you have, i know i can find a home for it very easy.

O yea I totally forgot about the blower lmao I def would not want an underdrive crank pulley then so I could get the most out of my blower. I mean I could def go with a smaller S/C pulley but it would be better if I left the crank pulley stock or get an overdrive crank pulley which would help the Alt at idle and bring up the boost a little although I don't think their is an overdrive crank pulley for the 4.0 SOHC is their? I wasn't even takin the blower into account when thinking about crank pulley replacement. My cobra has dual belt which makes things easier. I'm sure you could find a home for my stage 8 m112 I actually have 2 m112 stage 8 ported blowers, I painted both of them so nicely and one of them has a venom cooler. My cobra is 01 so it came naturally aspirated from the factory and the reason I went through all the trouble of gathering the parts such as the lower intake manifold and the timing cover and belt drive from an 03 cobra instead of just getting a kenne bell for the 01 cobra setup was for 2 reasons. First of which was at the time when I bought my cobra kenne bell had a much bigger better blower for the 03 cobra intake manifold then they did for the 01 cobra intake manifold plus the 03 motor can handle much more then the naturally aspirated 01 with aluminum internals and aluminum block. The 2nd reason which I am more likely to do is hellion makes a compound boost kit for the 03 cobras, supercharged twin turbo. If you go on youtube and watch some videos of compound boost cobras racing some sick cars in the texas mile it usually wins and its a very high horsepower setup but can also be tuned for the street as well. its like 1400 horse capable but on the street I would only run 650 to 700 horse. And no I don't have a roll bar or cage lol. I'm gonna make a removable one. They don't let me run at the tracks as my car is now lol. I did once at Raceway park and I ran too fast and they kicked me out. But long story short their is a home for both of my M112s lol but thanks a bunch for offering I doo appreciate it. If anybody knows of an overdrive crank pulley for the 4.0 SOHC that would be so amazingly god like lol but I'm pretty sure they're not out there.

 

[Devan]

I know this is way off base but listen to my baby scream. I wasn't expecting him to take off when he did so I nailed third and the tires started breakin loose and I slipped into the middle lane and gripped up and chased him down. He lifted when he saw me chasing him down right around when I was at the top of 3rd

cobra chasin vette

• Devan
• January 17, 2018