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tehsilver95lx
05-23-2012, 09:57 AM
we all know what they do,what are the possible negative affects?
5% supercharger ud gains?
10% supercharger ud gains?
( feel free to add all variants/combo's in between :p)
25% total ud???? < herd thats bad to do on a stock SC

i just wanted to know the possible boost/hp gain and the consequences of mis-using ud pulleys

90blkbrd
05-23-2012, 10:14 AM
we all know what they do,what are the possible negative affects?
5% supercharger ud gains?
10% supercharger ud gains?
( feel free to add all variants/combo's in between :p)
25% total ud???? < herd thats bad to do on a stock SC

i just wanted to know the possible boost/hp gain and the consequences of mis-using ud pulleys

Well first.

Underdrive pullies are used on the water pump, alternator, and crank pulley.
Overdrive pullies are used on the supercharger.

IMO

On a stock SC especially on a 89-93 anything more than a 5% OD pulley isn't worth it. The IC can't keep up with the heat and the inlet plenum is a restriction for the 10%.

Upgrade to the MP plenum and a FMIC and more OD can be beneficial.

The 25% OD system tends to eat rotors on daily driven cars. 15% is best for the street.

tehsilver95lx
05-23-2012, 04:19 PM
im getting a 94sc with a 5% od on the sc could i do a 10% ud set up and safely make decent hp? (Thanks for the info too man :D) and how would the 25% be achived 15%od with a 10% ud?

tehsilver95lx
05-27-2012, 10:49 PM
hello??????

90blkbrd
05-28-2012, 02:58 PM
im getting a 94sc with a 5% od on the sc could i do a 10% ud set up and safely make decent hp? (Thanks for the info too man :D) and how would the 25% be achived 15%od with a 10% ud?

Your 94 your getting has 15% od with a 10% ud. :o

Let me try this again. :eek:

OD = overdriving - you spin something faster
UD = underdriving - you spin something slower

So you would want to OD your supercharger to push more air into the engine and make more horsepower. You would want to UD your water pump air conditioning and alternator to free up horsepower. Thus no one UD's a supercharger. Let me rephrase that. No one underdrives a M90 supercharger.

You can get 5%, 10% and 15% OD pulleys for the supercharger.
You can get 5% and 10% OD pulleys to replace the Jack shaft.
You can get a 10% OD pulley for the crankshaft.
You can get a underdrive setup that includes a waterpump pulley, alternator pulley and crank pulley.

To create a 25% OD setup you should get a 5% Supercharger pulley, 10% jackshaft pulley and 10% crank pulley for a total of 25% OD.

A bone stock 94 with just a 5% pulley has much more needed to be done to it before you try to make more power by overdriving the M90 more.

The list below are a few ideas for better use of money before you want to spin the supercharger faster.

1. custom exhaust
2. better intercooler
3. underdrive pulleys
4. Binary editor software, quarterhorse chip, calibration file and base tune
5. Wideband 02 sensor


Don't take this wrong but before you reply you really should spend some time on this forum reading and understanding this car. You will learn way more reading about other setups than blindly asking questions.

Lycaon1349
05-29-2012, 06:32 AM
You will learn way more reading about other setups than blindly asking questions.

x2

agreed, try and build smarter, not quicker. the best thing you can do is build a good base for your more drastic upgrades. dont forget that when you modify one thing, you have to account for 10 more things that it will affect(not true all the time but its a good example to go by). my advice is that instead of jumping right into messing with pulleys, start off by upgrading your brakes if you havent done so already, and then work on making your car breathe better, starting with exhaust flow, then moving up into the engine bay with opening up your intake restrictions. youll notice more throttle response off the line and more general low end power by opening the system up to breathe, then if you just try to increase the rotation of the SC and force the boost through the small openings.