This is true.

We are not dealing with just a belt force, we must include the distance from the force to the center of the rotating axle as well. Force times distance is called torque, or moment. We must use the torque equation when there is rotation; we can use just force when the motion is in a straight line.

With a smaller pulley the distance from the force (the turning belt) to the centre of rotation (alternator shaft) is less than the original. The resistance to be overcome hasn't changed, so torques are set equal to each other: Force times Distance (original pulley) = Force times Distance (new smaller pulley).
Smaller pulley diameter means the force applied by it's belt has to increase so it's F x D still equals the original F x D.

In other words, yes, the load on the engine must increase.

I guess.

 

^^ hmmm I didn't study engineering or anything so I'd defiantly listen to you but in my mind wouldn't it be easier to turn a smaller diameter pulley than a larger one cause the larger one would have more torque because of leverage and the force is the same amount O wait I just answered my own question it would be harder to turn the smaller pulley because there is less torque/ leverage to turn it And the load would stay the same

 

Yeah just think of a brake disc. Would it be easier if you grabbed the outside of a really big disc to stop it, or grab a teeny tiny diameter disc and stop it?

 

Yea I thought of how bigger rims have more leverage

 

it'd probably be hard to do, but what if you basically make a "oem style"(clone) pulley out of say aluminum(or something lighter than the brick we currently have), woudn't that make it the same size and less weight?(even if it isn't as light as the already well known lightweight+UD pulley rrm sells)

that would probably make the most sense wouldn't it?...(at least in my mind)

 

this is pretty much my plan as well as remove some material like rrm did with holes

 

Optional: You could finish the aluminum part by anodizing. Basically the part is submerged in an acid bath that has a piece of lead in it, and a current is applied. The surface of the part converts to aluminum oxide which is a hard ceramic, like for example the hard granules that make sandpaper. It goes to a depth of several thou. After the acid bath is done, the part is placed in boiling water that has dye in it. The surface pores seal up and the dye adds colour, your choice of the bright reds, yellows, blues, or gloss black you often see on bling bling car parts. If no dye then the part is a nice light gray. Should be a vendor near you.

It adds no weight and you have a very hard surface that withstands wear. That being said, I don't know if it's really necessary for this application or not.

p.s. At one place I worked we made our own little anodizing set-up with a cute desktop-sized tank. Worked awesome. Then I built a power supply, its here at home, can do my own anodizing if I bother to buy some acid. Problem is, I need a machine shop here too so I can make the parts to anodize Ah, one day...

 

or....you could just buy/find random chunks of aluminium to anodize..lol

 

Purple anodized pullies would be sick , or even just the single crank pulley. Rob have you chosen this for your project or is it still in the air?

 

anodized aluminum makes me happy...

 

^not in the pants i hope...lol

 

i think i posted before i plan on putting a anodized or i think it an ecoat finish which is black and not as hard on the belts but has more grip.

as for make your own anodizer i have studied this before and was an idea but ive heard can be dangerous (fumes etc)

 

i did my proposal presentation and went over well so i think its a go, i still need to go consult my old machining boss for help but as it stands i will be making one and doing the testing.

If everything goes well and the part is safe and provides a decent performance upgrade i will let you all know and will go from there to see if its worth me getting some machined up (im not goona make a bunch of parts if i cant at least break even, in the plus would be nice ) will probably be closer to July 2013

 

so apparently i missed this thread showing one from ebay that looks like oem size but probably not all that light

https://www.evolutionm.net/forums/04...ion-issue.html

 

So update time measured and made in CAD an OEM pulley and a first design light weight pulley as well as a dampened light weight pulley.

as for the specs on CAD the oem pulley in all steel forgot about damper weighted 2.6 kg,

my Aluminum T 6061 LWP weighted .525kg weight saving of 80% while still having lots of metal

the Aluminum T6061/rubber DLWP weighted .550kg weight savings of about 72%

so far this is looking promising even with the added rubber damper if needed, only problem is when i weighted the OEM pulley on a scale it came back with 1.76kg not sure if the rubber makes that much weight difference will update the model tomorrow and try and provide some better numbers