lowtegsr

ok me and a friend were discussing this last night. i thought that the aftermarket pulleys were smaller which caused the crankshaft to spin faster therefore producing more torque/hp. and he said the only reason was because they were more lightwieght and it had nothin to do with the size of it at all. could someone please help me out on this with some useful information. thanks

yc_dc4mar

they are lighter. if it was smaller then you would need new belts as well. and smaller wouldnt make it any faster thats just stupid.

patriot

iTrader: (2)

actually most of them are atleast a tad smaller... my UR(ripoff) is hella light especially being a single belt pulley and it required a smaller belt... its called underdriving... basicly changing a drive ratio(like your transmission) to make it easier for the engine to spin the accesories therefore freeing up some parasitic loss

oh and yea...it doesnt make the crank spin faster...it allows the engine to accelerate quicker

lowtegsr

so is it true that unless ur boosted or somethin, that u shouldn't put on an aftermarket underdrive pulley? i heard that the oem are setup with specs for ur car and can mess up your bearings?

DC2BUD

Aftermarket crank pulleys can mess up your bearings because of the harmonics. Powersteering and alternator pulleys dont, you might not charge your battery enough with the alternator pulley if you have a big stereo.

patriot

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DC2BUD &raquo;</TD></TR><TR><TD CLASS="quote">Aftermarket crank pulleys can mess up your bearings because of the harmonics. Powersteering and alternator pulleys dont, you might not charge your battery enough with the alternator pulley if you have a big stereo.</TD></TR></TABLE>
40K miles on a single belt pulley. Will be pulling pistons in a couple months...I'll let you know how they look. Harmonics are more of an issue with "big" power and high revs...like frequent 9K plus. Oh yea, I also have a JDM YS1 tranny so @70mph im singing @ 4000rpms

96TEG_gsr

if the underdrive/ PS/ alt. pulleys are "precision" made, why would it throw off the harmonics of the engine? if it's a perfectly rotating system, there shouldn't be any problem?

i could understand if there were a chunk missing out of your main pulley, but if it's completely intact, there shouldn't be a problem.

i'm in the process of changing some parts out and that's on my list. only because my dad tore a chunk out of the main pulley...! but i'm also striving for at least 370WHP by late next year. so the pulley kit transfer would be neccessary.
which by the way... anybody recommend a certain brand? i'm leaning toward an unorthodox racing kit. (not the street kit, only because the price is right. (ebay))

grundle

changing the crank puly most are not balancers. a type r crank pully will produce some underdrive compaired to gsr/ls.

as for the use of underdrive pullies. I have a set of Aem underdrives on my teg they are a different size then oem and the set comes with different length belts. they just alow the motor to spin the accesories at a slower speed to relieve some parasitic power loss.

I got the set for the ls motor then blew that one up and got a type r so now im running the underdriven type r oem balancer and some underdrive pullies. my ac isn't as cold as it used to be and my alternator only charges at 12.75v

bakertime

iTrader: (1)

Stay away from something lighter then stock....The weight of the stock one does have a harmonic balancing effect. Because the crank flexes more the further away you go from the flywheel, the balancer helps offset this. Basically, stop trying to find the cheap mods that get you a few horsepower...in the end it's not worth the risk. I have read posts where people have used them successfully for years, but only because the product they chose was very well made. Just keep this in mind.

Steve Dinan of Dinan BMW on Power Pulleys:
http://www.dinancars.com/bmw/t...amper


Modified by bakertime at 11:30 AM 4/25/2008

WinningNinja

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bakertime &raquo;</TD></TR><TR><TD CLASS="quote">Steve Dinan of Dinan BMW on Power Pulleys:
http://www.dinancars.com/bmw/t...amper</TD></TR></TABLE>
Great read, thank you for that.

patriot

iTrader: (2)

http://theoldone.com/components/fluidampr/

^^^really your best bet

and no, i still havent torn my engine apart.
waitin on the new one to get back from the machine shop/

96TEG_gsr

so what would be the best thing to do instead of changing out for light weight if i tore a chunk out of my original underdrive? go bac with oem or find a type r?

patriot

iTrader: (2)

i havent done much research on the differences between OEM pulleys(in fact none at all) but if its true what they say; that the type-r is slightly smaller, i'd go with that. maybe "CTR N1" or whatever if you dont have a/c or p/s like me