What's the deal with pulleys??

[ShagginJet]

Alright, so i seem to be lost. I was under the impression that a larger, light weight pulley would give the car a ittle more HP. Talked to a friend, and now I'm not sure.

Someone enlgithen me!!

Friend: The stock crank pulley is 5.2 inches in diameter, so for every rotation, it moves 16.3 inches of belt. (Get it? 16.3 inches is the circumference of the pulley, and since the belt wraps around the outside of the pulley, that's how much the belt gets moved.) The Unorthodox Racing pulley we installed is only 4.15 inches, so for the same revolution, only 13 inches of belt get yanked through. With the belt moving more slowly, all the accessories move more slowly, and less power is lost to the accessories.

Dan: that doesn't make sense

Friend: It explains how the smaller pulley moves the belt slower.

[pdiggitydogg]

yes the larger the pulley is less it has to spin to create the same amount of power or movement. think of a bus wheel and stock civic wheels (14"), the bus wheel is gigantic and spins slower but covers more ground, where the civic's 14" spins a sh*tload more to cover the same ground. As for the weight, the heavier it is the more power it takes to spin, its the same priniple of having lighter rims. If the rim is light (and big, say 17") it looks good and at the same time takes less to move which means the car can look good and at the same time perform better than one that has the same size but heavier rims.

Basically those pulleys that your asking about are real good. No youre not going to get tons of hp out of them but you will get some.

I hope this helps out...I know I could describe it better...and probably shorter if I had pictures...I like to draw diagrams:D

[ShagginJet]

His is what I was thinking about, what do you think?

http://www.massivemotorsports.com/main/obx_crankpulley.htm

[pdiggitydogg]

I'd go with AEM tru power or whatever theyre called. you get 2 (crank and PSteering) plus the belts for like 130 on ebay. plus you can get colors if you get them from a dealer;)
Im planning on pulleys being my next mod along with a cam gear so I can set my distributer back to OE spec and turn the cam instead. Not that you care...but I shared anyway:D

[ShagginJet]

Don't have p stearing or AC, so i don't really need the AEM one. but yeah i was looking at that.

[a96710]

I have the AEM Tru-time power pulley set and I noticed a lil gain with a quicker throttle response...I also did an Unorthodox crank pulley and noticed some gains with that also

[ShagginJet]

I heard that the unorthodox is actually smaller thought...?

[a96710]

I'm not sure if it's smaller...but I definetely know it weighs about half of what the stock one does

[pdiggitydogg]

ok then I would go with the unorthodox crank pulley. it being lighter is 1/2 the battle for power

[ShagginJet]

But bigger is better, isn't it?

[nonovurbizniz]

NO NO NO NO

Bigger is not better. Here's how it works. If you put on a bigger crank pully lighter or heavier what it does is turn all of your accesories faster. this does not help you at all. In fact what it will do is burn out your alternator. Alternator's are design to performe optimally at anywhere from 2k->4k above this they produce too much power and CAN (not always) FRY your electical system. It also lighter or heavier will take AWAY HP's. A smaller crank pully will have less drag on the crankshaft and it will UNDERDRIVE your accesories (hence the name underdrive pullys). So it provides power in two ways.
1. It weighs less and has a SMALLER diameter there by taking less power per turn.
2. Transfers LESS power to the accesories freeing up this hp for the flywheel and in-turn (hahaha) the wheels. (this is also a benifit in high reving engines because over-revving accesories leads to where out. so the underdriving charactoristics of the Pullys actually preserves your accesories.)

[ShagginJet]

But if you're moving the belt slower, then the alternator won't be spinning quick enough, and it won't put out the same electrical current and amprage. This will cause the spark plugs to not have enough juice, and will most likely cause havoc on you electical system...

Is this not correct??

[pdiggitydogg]

thats why you combine the two! hell spending money can be fun

[ShagginJet]

So let me get this right once and for all, i'm supoose to get a smaller crank pulley and then a larger pulley for my alternator?

[pdiggitydogg]

yep

[pdiggitydogg]

........im pretty sure;)

[cashizslick]

if you get a pulley kit, make sure your kit comes with a crank pulley.

[Honda530]

Be careful with teh Crank Pulley. There ahve been some cases where people have changed it and have had problems. Im not saying that you will but just be careful. Id have a shop do it too its a pain to get that crank pulley off too.

[nonovurbizniz]

Originally posted by ShagginJet
But if you're moving the belt slower, then the alternator won't be spinning quick enough, and it won't put out the same electrical current and amprage. This will cause the spark plugs to not have enough juice, and will most likely cause havoc on you electical system...

Is this not correct??

No because like i said the output of any alternator varies greatly depending on rpm. for honda's the charge is perfect at 2.5k-3k rpm this is hardly the average driving rpm of a civic owner. this means that if it's spinning slower then the new perfect charge is at say... 3.5k-4k. that's no big deal for a car with a 7k rpm rev limit. so No this will not affect your spark at all. beyond that your spark plugs will take as much spark as your Bat. will supply not your alternator. and as far as the electrical system that's what voltage regulators are for. (in case you didn't know you have one and it's purpose is to prevent running too high or too low a voltage to the electrical system. regardless of the output of the alternator)

[ShagginJet]

good deal... ty for your input.