etec-II underdrive pulley development

[Daox]

NOTE: the official group buy thread for this pulley is here:
E-TEC II underdrive pulley group buy - Chevrolet Aveo forum and owners club - AveoForum.com
Post in that thread if you're interested in one.

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I'm starting a new thread on this to separate it from other discussion that had been going on. I know there is a lightweight pulley available from Xaiogary, but the price is a bit high and I think we can do better if we do a group buy on the board here.

Anyway, I have actually been thinking about this for a while. An underdrive crankshaft pulley is a very simple mod that is usually pretty low cost. It works not only by being lighter in weight than the original pulley (less rotational mass like a lightweight flywheel), but also by being smaller in diameter. This in turn spins your accessories slower which frees up some horsepower as well.

I'd love to get input and know if people are interested. If all goes well we can put together a group buy. The more people we get the cheaper the parts get, thats the way things work. So, let me know if you are interested.

People interested:
Daox
reddemonx92
serega12
one_man_jam
thehunterooo
xintersecty
AveoSS

theclarkfam???
petrified.rabbit???
bdc87???

I'm also still interested in knowing how the ecotec pulley compares to the etec. If anyone could even get a picture of the ecotec pulley we could probably know right there if it won't work.

So, I have modeled up the stock pulley at this point. I figured I'd share some pretty pictures with you guys (we all like pics after all).

[AveoSS]

I'm on this deal too! Would we need to replace the OEM belt with a smaller one since the pulley be smaller?

[thehunterooo]

its the same size I think, but weighs alot less

[AveoSS]

No, he sayd its a underdrive(smaller). Well probably have to get a smaller aftermarket belt.

[trempus]

it's called underdrive but really means light weight

[reddemonx92]

yea i dont think they will make pulleys that require aftermarket belts

[Daox]

The quotes are all in and I'm putting together an official list for the group buy.

etec underdrive pulley group buy

[Pontiac1976]

Anyway, I have actually been thinking about this for a while. An underdrive crankshaft pulley is a very simple mod that is usually pretty low cost. It works not only by being lighter in weight than the original pulley (less rotational mass like a lightweight flywheel), but also by being smaller in diameter. This in turn spins your accessories slower which frees up some horsepower as well.

I thought that if the crank pulley was bigger that it would slow the belt down (rotate truns of the belt) smaller would speed up the belt & speed up the rpms of the Alt,A/c pump.
Just trying to under stand. maybe I lost something from the working on 1970's v8?? thanks

[Daox]

Take a look at the picture below. If each of these circles has to roll 360 degrees on the ground, the larger one will go farther. That means that if you put a belt on both of them and spin them the same rpm, the larger one will make your belt travel faster.

[petrified.rabbit]

your thinking of a bicycle, or chain driven vehicle where if you make the gear is bigger on the wheel then pedaling will turn the wheel slower. Thats because the pedal crank gear stays the same size. If you enlarge the crank gear instead, you will go faster.