dimming issue

[dman4486 5,000+ posts]

Obviously in an extremely dramatic case, if there was a large decrease in pulley size, say from 10" to 3" there would have to be a change in belt length since the tensioner could not make up for that big of a difference, correct?

that is the only reason for a shorter belt

 

[MikeyB 5,000+ posts]

that is the only reason for a shorter belt

//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[SPL140.2 5,000+ posts]

that is the only reason for a shorter belt

that is not entirely true, with a tensioner all it does is make the belt tighter, If you have a smaller pulley and use the stock belt and in some instances the alternator moves forward or backward to take up the slack of the stock belt, with a smaller pulley on the alternator you may have to push the alternator all the way back to tighten the belt, which will not make the smaller pulley spin faster and thats what you want. You want the smaller pulley on the alternator to spin faster than the stock one. FYI, if what you guys are saying is true why is it they put smaller pulleys on the alternator than whats on the stock and highly recommend not changing out pulleys from the stock alternator to the high output alternator?? hmmnn

MikeyB said it right you want to keep the ratio the same, crank pulley to alternator pulley and with the shorter belt the high output alternators pulley will spin faster.

egg

 

[dman4486 5,000+ posts]

that is not entirely true, with a tensioner all it does is make the belt tighter, If you have a smaller pulley and use the stock belt and in some instances the alternator moves forward or backward to take up the slack of the stock belt, with a smaller pulley on the alternator you may have to push the alternator all the way back to tighten the belt, which will not make the smaller pulley spin faster and thats what you want. You want the smaller pulley on the alternator to spin faster than the stock one. FYI, if what you guys are saying is true why is it they put smaller pulleys on the alternator than whats on the stock and highly recommend not changing out pulleys from the stock alternator to the high output alternator?? hmmnn
MikeyB said it right you want to keep the ratio the same, crank pulley to alternator pulley and with the shorter belt the high output alternators pulley will spin faster.

egg

Bullshit

location of the pulley or belt length do not make any difference to rpm at which it turns

 

[SPL140.2 5,000+ posts]

Either way I have a stock pulley Diameter of 2.5", the Iraggi Pulley is 2". So the way I am looking at it, is if I was to decrease the length of the belt, only the difference in radius should matter, correct? So that would be a difference of .25" which I think the tensioner could more than make up for......I could be wrong just the way Im lookin at it

you would have to find a belt thats .5" shorter than the stock belt.

egg

 

[SPL140.2 5,000+ posts]

Bullshit
location of the pulley or belt length do not make any difference to rpm at which it turns

test it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif There is a reason

egg

 

[SPL140.2 5,000+ posts]

Bullshit
location of the pulley or belt length do not make any difference to rpm at which it turns

your absolutley right the crank pulley will spin with no difference, its the alterantors pulley that will spin faster

egg

 

[dman4486 5,000+ posts]

test it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif There is a reason
egg

either you are not explaining well, or full of sh!t....i have worked on these issues many times, and the only difference in rpm relative to the main will be the ratio of the pulleys PERIOD

I will be in class for the next 2 hours...so...get your bike out of the closet, and lengthen the rear forks and chain...then explain to me why it didn't work.

 

[SPL140.2 5,000+ posts]

either you are not explaining well, or full of sh!t....i have worked on these issues many times, and the only difference in rpm relative to the main will be the ratio of the pulleys PERIOD
I will be in class for the next 2 hours...so...get your bike out of the closet, and lengthen the rear forks and chain...then explain to me why it didn't work.

Im sure someone will chime in soon on this topic //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif I give up:verymad://content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

egg

 

[fatryan 5,000+ posts]

^^^^//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif thats like saying your with your friend riding bikes, one has a 10 speed with big tires and you riding a regular size bike with smaller tires. If your both riding at the same speed or rpm, the smaller tires are rotating more and faster than the larger tires on the 10 speed //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Same thing applies to belts //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif But what do I know //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif
egg

that has nothing to do with the belt length. youre comparing the size of the wheel (i.e. pulley). yes, different size pulleys will produce different output. but with identical pulleys and different sized belts, the output will be the same. trust me on this one.

 

[fatryan 5,000+ posts]

It doesn't matter if the belt is 1 mile long. The rpms of the alternator are directly proportional to the size of crank pulley, the size of the alternator pulley, and the rpms of the engine. Put aside slipping for a moment, think of the belt as a bike chain, the crank pulley will rotate (x) amount and will move the chain x amount times the cranks size/ratio=, the chain then moves y amount over the alt pulley rotating the pulley y amount divided by its size/ratio=alt rpms. It doesn't matter how many rotations the belt makes, what matters is that any movement of the belt transfers to adjoining pulleys. Sure a smaller belt can help with slipping but it will not make anything faster.

thank you //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

yeah, ive done a number of mechanics problems in class with this same situation, and i KNOW the belt length has no affect

edit: to really drive this into your head...the PULLEY size will affect output, but BELT length ALONE will have 0 affect.

 

[SPL140.2 5,000+ posts]

I had a little talk with a certain fella who builds them look at this example chart:

15" Belt

Crank pulley- Alternator Pulley- %

6"- 6"- 0%

750 rpms- 750 rpms

6"- 4"- 34% +- rpm increase on alternator pulley

750 rpms- 1005 rpms

6"- 2"- 68% +- rpm increase on alternator pulley

750 rpms- 1260 rpms

_____________________________________________________________

Shorter Belt applied by taking the difference from the stock pulley to the HO pulley.

Crank pulley- Alternator pulley- Belt size- %

6"- 6"- 15"- 0%

750 rpms- 750 rpms

6"- 4"- 13"- 13% +- rpm increase

750 rpms- 1136 rpms

6"- 2"- 11"- 27% +- rpm increase

750 rpms- 1600 rpms-

______________________________________________________________

Difference between changing out belts

Alternator pulley- Difference (increased rpms)

6"- 0

4"- 131 rpms

2" - 340 rpms

_______________________________________________________________

Just by changing the belt you increased 340 rpms or 27% at idle using the 2" HO pulley than using the stock belt with the 2" pulley. NOTEThis chart is not a test and the numbers are for informational use only and used as an exampleMost vehicles have a 3 to 1 ratio by using a shorter belt you try to match this ratio with the smaller pulley on a HO alternator

egg

 

[IgnoreMe 5,000+ posts]

im gonna respectfully disagree with you egg, as well as what im assuming to be iraggi's example.

ratios are based on the correlation between the drive and the driven pulley. they have nothing to do with the belt. the only difference you are going to get by using a smaller belt is having the belt complete 1 full revolution faster than if you had a longer one. a 3:1 pulley on an HO alt means it will spin at 3 times the crank pulley speed, regardless how long or short the belt is.

edit: blownmind probably has put it best using his bike chain example.

 

[IgnoreMe 5,000+ posts]

i just did a little experiment //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i have 2 same size perfectly round pencil/pen holders (imagine a plastic glass that has a perfect 90 degree angle, not tapered) with a t-shape in them which allows me to see how many rotations they make and a candle holder, which has the same characteristic but is a decent bit smaller. i bent the wick so i can see when it makes a full rotation.

i placed the two pen holders on the table in front of the computer. i tied a wire (with a very flexible rubbery jacket which sticks really well to the 3 objects im using) up to a random length put it around them, made sure the wire was taught and turned the pen holders. sure enough as expected. each one made 1 full rotation. 1:1 ratio

i then did it to 1 pen holder and the candle holder. 1.25:1 ratio with the same wire length.

i then untied the wire, made it quite a bit shorter, pretty **** short actually lol, and did it again. once again a 1:1 ratio for the pen holders.

then the candle holder and the pen holder...guess what? 1.25:1 ratio

it makes no difference in my quick test. and i cant believe im even doing this shit at 2:30 in the god **** morning haha

 

[dman4486 5,000+ posts]

notice everytime the belt changes, the size of the pulley changes....belt length is taking up the slack not changing rpm