H.O. alternator made me LOOSE voltage?

[spoonraker 10+ year member]

I was trying to make it easy for people to understand, since nobody seems to know a **** thing about it.

I know alternators don't use permanent magnets, I guess saying "spins wires near a magnetic field" would have been better, but nobody is perfect.

As for the second quote, again I know that when you hit a certain point the amperage peaks, but in a general sense it's true. I was just trying to convey to people the reason for a smaller pulley.

 

[NewToTheGrounds 10+ year member]

so switching to a smaller pully is gunna allow a higher spin to the alty so could i do this with my stock alty to gain more out of it?(switch to a smaller pully?)

 

[IgnoreMe 5,000+ posts]

I was trying to make it easy for people to understand, since nobody seems to know a **** thing about it.
I know alternators don't use permanent magnets, I guess saying "spins wires near a magnetic field" would have been better, but nobody is perfect.

As for the second quote, again I know that when you hit a certain point the amperage peaks, but in a general sense it's true. I was just trying to convey to people the reason for a smaller pulley.

no offense intended to you bro. sorry if it came off like that. the only reason i quoted that last part was because a member on here was at a comp where a guy in w caprice revved his engine to the redline for like a minute or two and ended up with a huge engine knock. and when this member asked why the guy did that he got the response of "well the faster the alternator spins the more power it makes" //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

just dont want some crazy dudes to screw themselves over by taking that last part to the extreme.

 

[IgnoreMe 5,000+ posts]

so switching to a smaller pully is gunna allow a higher spin to the alty so could i do this with my stock alty to gain more out of it?(switch to a smaller pully?)

yes you can do this with your stock alternator but im not sure what ratio pulley is already on there and where that alternator stops improving in amperage output so i couldnt tell you how much its gonna help.

 

[spoonraker 10+ year member]

none taken george,

as for putting a smaller pulley on a stock alt, It's completely dependent on the car. I'd say for the most part you won't see much of an improvement. You just need to figure out exactly how much power your stock alt makes and at what RPM it does it at.

 

[NewToTheGrounds 10+ year member]

aight thanks for the input

 

[OoMesKoO 10+ year member]

Thats all good. But for some reason even after i switched to the smallest possible pulley, it only improved my problem a little bit. On the website, it says it puts out 85 amps at 800 rpm. Well i idle at 500..... so im getting what.... like 50 amps?

That sucks.

 

[IgnoreMe 5,000+ posts]

any bluish coloring on any pulleys by chance?

 

[OoMesKoO 10+ year member]

Hmmmm... i wasnt sure, so i just went to check. Nothing. I think i need to get the idle in my tahoe up. If i hold the brake pedal, and get the rpms to go up like 100... it charges perfectly.

 

[IgnoreMe 5,000+ posts]

Hmmmm... i wasnt sure, so i just went to check. Nothing. I think i need to get the idle in my tahoe up. If i hold the brake pedal, and get the rpms to go up like 100... it charges perfectly.

what year is this tahoe?

problem with that is, if the car is fairly new all idle control is done by the computer. there is no idle adjustment that you can do without reprogramming it. but like i said i dont know what year it is but im willing to bet its controlled by computer anyhow.

 

[mokedaddy 5,000+ posts]

Having a v8 that idles at 500 rpms is normal. There probably isnt much else you can do except maybe turn your stereo down at stoplights if it bothers you that much.

 

[Twistid 5,000+ posts]

i idle at like 800rpm and have my sundown at .7 and it does fine at stoplights, i dont even get dimming lights

 

[spoonraker 10+ year member]

That a pretty low idle and your alt doesn't put out much at low speeds....so somehow you've got to get it spinning faster.

Either an even smaller pulley, or a higher idle...unless you know another way to make it spin faster.

 

[ballzitch]

hey OoMesKoO,

i have the same problem. i have a f-150 with a 5.4v8 and when im in gear the idle is about 500 also. i pulled the alternator and took it to a shop to be tested. we played with the rpms of the alt and anything under about 1950rpm it wouldnt even charge. but once it reached about 2000-2100 it put out over 100a. when im in neutral or park i run about 600-650 rpms and it charges perfect and i dont have the big3 done yet. i called a friend of mine he is a mechanic and he said take it to ford and have them adjust the neutral rps to around 800. right now i am looking into a tuner so i can adjust it myself just incase i chew up too much gas.

and by the way the pulley we put on was the smallest possible and it didnt help a tad.

 

[IgnoreMe 5,000+ posts]

hey OoMesKoO,i have the same problem. i have a f-150 with a 5.4v8 and when im in gear the idle is about 500 also. i pulled the alternator and took it to a shop to be tested. we played with the rpms of the alt and anything under about 1950rpm it wouldnt even charge. but once it reached about 2000-2100 it put out over 100a. when im in neutral or park i run about 600-650 rpms and it charges perfect and i dont have the big3 done yet. i called a friend of mine he is a mechanic and he said take it to ford and have them adjust the neutral rps to around 800. right now i am looking into a tuner so i can adjust it myself just incase i chew up too much gas.

and by the way the pulley we put on was the smallest possible and it didnt help a tad.

some shops wont adjust your idle speed to anything but manufactures spec //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

a new pulley will help, it just has to be a really high ratio pulley, but we've already established that like ballzitch, oomeskoo has the smallest pulley he could get and it still isnt running how it should be. so like people have said you gotta figure out a way to get the idle speed up. try a shop and see if they will do it. an independent shop might be a better idea.