well here it is, whats the final word on underdrive pulleys?

use just the crank or the crank and the alternator? is the money worth the gain?
please if ya have em or have read enough on em, i wanna hear good/bad and to use one or both pulleys. also about how much ya paid and what kind they are. also, if you are running without ac or without emissions or without both.

 

Never had them, but from what I've read:

If you have a juiced stereo system, use just the crank pulley*

If regular stereo sys, crank & alt pulley*

* Some people have experianced low voltage/lights running the alt pulley at idle speeds. They either riaed the idle of the engine, or installed a higher amp alt to compensate.

I have also read that pulleys should be the next to last mod done, w/a custom chip burned to take into account all the mods done to the engine.

next.....

 

I have used the crank and alt one and i wasent putting out enough juice so i just used the one for the crank . I think i have a POS alternator autohell need i say more. Any ways i did notice better throtle response the care fet like it had more power off the line and i also got a hudge gain in gas milage. The gain in gas milage will make them pay for them self after several fillups at the way gas keeps going up ****IN OPEC and my 2.50 a gallon today.

 

I have experimented with this more than anybody-

I have had the stock 105 amp alt. with both-crap..... with only crank pulley-crap

I have tried my $400 200amp powermaster alt on it with both crank and alt underdrive pulleys, worked fine BUT hit the STB(larger housing), ANDthe power needed to turn the magnetic feild of a 200amp alt drained back what gains you get from the smaller pulleys.

I now run a 140amp alt with just the crank pulley and do have a noticeble gain with just the crank pulley- tried the alt also and still get discharge

conclusion- I will only run a crank pulley with a 140amp minimum alt (No alt powerpulley)

 

I've had them on all my past rides. I mainly suggest crank only unless it is strickly a race ride.

I just went back from crank/alt, to crank only because I wasnt getting enough juice while suck in traffic to run my fans.

 

I would recommend just the crank pulley. But if you are interested in removing the a/c compressor, do that also. The gain will be noticeable plus you are performing some weight reduction. I also eliminated the idler pulley so I am only running the alternator, water pump, power steering, crank and tensioner. You have to remember that everything adds up.

 

i'm running a crank and alt pulley. have no problems with power. i do notice the headlights dimming a little while idling with fans on, ac, radio, but no major problems. they come right back to full strength as soon as the engine is reved a little. the voltage does not drop very much, doesn't keep dropping either. that's, as far as i know, on a stock alt. too.

 

"LUKE , USE THE SEARCH!"

 

i did search, but i want more opinions. plus wont this make it easier next time someone searches for underdrive pulleys and this comes up? i know if i had seen a post like this it would have been all the info i need in one place not clicking on 300 diff posts to gather alittle bit.

 

No because you wont get all the information here and next time someone wants info about them they will make a new post up like you did and say "i didnt feel like searching through all the other posts" and it will go on and on blah blah blah.

 

if you know that it will go on and on....why make a big deal about it now??

 

im not

 

Can anyone tell me the outside diameter of an underdrive crank pulley? I was thinking about making one at the school machine shop but do not know what diameter to make it.
Thanks

 

It will fit inside the old pully and is baybe a 1/4 of an inch smaller then your harmonic balancer.