problems with underdrive pulleys

[slider85]

When I asked a professional about Underdrive Pullies he advised against them for a daily driver because they can wear out your alternator, drain batteries, and just flat out cause problems. I know, I know, some of you out there are running them, and that's fine. Also, I was advised that when you Underdrive the alternator and put more load on it(AC, stereo, defroster) it will wear down.

So, after all that, I was thinking that if anyone knew if this exists. An alternator that puts out the same or more voltage than the stock one, but is designed to spin slower? Because if someone had that then that could solve all the problems.

Hope that makes sense.

 

[teme]

hmmps, i don't get it... why would lighter pulleys weard down alternator etc...?

Either it's lightweight or stock pulley, the same rpm it will spin, and with the same rpm it spins alternator and etc...
So alternator and ac etc, works just the same with stock pulley and with lighter one.

But if here's some catch i don't know, please explain why it is otherwise.

Something to do with lighter one being not so balanced than the stock maybe ?

 

[slider85]

underdrive pullies spin the alternator and power steering and whatever else slower so that the engine can use that lost power towards the tranny and out to the wheels. I personally have not figured out how they do that, but I'm working on it. Yes they are lighter so the engine does not work as hard to spin them, "freeing-up" horsepower.

http://www.sportruck.com/howto/highways.htm
this website briefly describes what happens

 

[IMMORTALSPYDER]

I had them on my last car and had no problems.

 

[GSGoinFast]

it makes them spin slower by having a smaller circumference. if the circumference is smaller, for each rotation of the crank, the belt will move a shorter length. i dunno if that makes sense or not but it does for me. ive had mine for about 6 months now and the only problem ive had was squeeking belts which were replaced and have stopped squeeking.

 

[Redmachine]

smaller=faster
larger=slower
the larger the diameter the longer it takes the belt to move a complete revolution, hence underdriving
If you look at a complete underdrive pulley kit all of the new pulleys will be bigger.

 

[GSGoinFast]

smaller=faster
larger=slower
the larger the diameter the longer it takes the belt to move a complete revolution, hence underdriving
If you look at a complete underdrive pulley kit all of the new pulleys will be bigger.

well i guess were both right and both wrong. i was talking about crank pulley, and i think your talking about accessory pullies. if the crank pulley is smaller, the accessories will spin slower. if the accessory pullies are larger, the accessories will spin slower.

 

[Redmachine]

well i guess were both right and both wrong. i was talking about crank pulley, and i think your talking about accessory pullies. if the crank pulley is smaller, the accessories will spin slower. if the accessory pullies are larger, the accessories will spin slower.

Yeah that's what I meant. I actually havn't seen the crank pulleys for our cars yet, but have installed kits on mustangs before and that's what I noticed

 

[teme]

Yeah that's what I meant. I actually havn't seen the crank pulleys for our cars yet, but have installed kits on mustangs before and that's what I noticed

http://www.saunalahti.fi/teme666/pulley.jpg <-- here's one (one that i have now installed)

 

[speedy13]

well i guess were both right and both wrong. i was talking about crank pulley, and i think your talking about accessory pullies. if the crank pulley is smaller, the accessories will spin slower. if the accessory pullies are larger, the accessories will spin slower.

GS is right.the accesories will have less load now that their spinning less than before.thats why it's called "Underdrive" pulley because they work about 20% less then they did before.Enough to free up some ponies but not too much so it affects daily driving.The only people that have had problems are those with a powerfull audio system in their cars.othr than that i got a rockford 250 watts with a 10'inch bazooka and have been running it without a problem.

 

[be989]

Aren't there just lightened pullies, not underdrive ones? Won't lightened pullies with the same diameters or circumference yield a noticeable gain in power?

 

[speedy13]

yeah tey will,but if the accesories are underdriven you will get even more gain.

 

[Wizard]

http://unorthodoxracing.com/faq_pulleys.html

Read second section. From the innovators of underdrive.

Wiz

 

[be989]

yeah tey will,but if the accesories are underdriven you will get even more gain.

Yeah but wouldn't that eliminate the "fear" of having your accessorries working "under par" and having to deal with having to get shorter belts?

 

[speedy13]

yes,but the people that are making these pulleys are DESIGNING them in a matter that it will not affect daily driving.I have tested my alternator and it test exactly the same as it did with the stock pulley.Thats why I like to get this part from somebody that at leats has a name for making this part.

 

[aliczander]

if your worried aobut your altanator you can get the complete set from unorthidox, imho its a complete waste of money because the only pully that will give you any noticable hp is the udp and i dont know anyone who has had any problems
aliczander

 

[GSGoinFast]

there is no fear. my battery is going fine, putting out 13.5 volts when its running.

 

[aliczander]

can i powder coat my udp, or will that cause any problems

 

[Defiant]

it makes them spin slower by having a smaller circumference. if the circumference is smaller, for each rotation of the crank, the belt will move a shorter length. i dunno if that makes sense or not but it does for me. ive had mine for about 6 months now and the only problem ive had was squeeking belts which were replaced and have stopped squeeking.

It's more a question of radius- the smaller the diameter, the shorter the effective lever. Just like the cranks on a bicycle.

 

[LaserDad91]

This might help. Go here and look for “Bucks” posts. He had info on a high output alternator and a P/N.

http://www.dsmtuners.com/forums/showthread.php?p=1120566#post1120566

 

[GSGoinFast]

It's more a question of radius- the smaller the diameter, the shorter the effective lever. Just like the cranks on a bicycle.

well if it has a shorter diameter then it has a shorter radius.