GrayFox

And how are they supposed to improve performance?

Jerry

Megatron

A "Pulley" improves performance by decreasing the "losses" to your engine power. Imagine just the alternator pulley... if you increase the size of the pulley on the alternator, you reduce the load on your engine... That reduction in load frees up more power to be used elsewhere (i.e. to your wheels). Of course, if you did that, your alternator now runs slower and generates less electrical current. So you can play this game with any of the pulleys your engine has...

All you are doing is stealing power from one place to give to another... You know the laws of physics... Conservation of Energy... you can't get something from nothing.

Hope this makes sense...

260 HP

iTrader: (3)

Pulleys are the round things with rubber belt around them. The one on the bottom of the engine turns the power steering, AC compressor, and alternator pulleys.

The after market pulleys are lighter than the stock ones (the lighter they are, the easier they turn, the less torque/HP needed to turn them) and of different diameter. The crank pulley is smaller and the other pulleys are bigger.

260 HP

iTrader: (3)

Damn! Megatron beat me to it....

GrayFox

Hmm,

Sounds like something you might do after you remove the spare tire and jack to lighten
the car....

Jerry

kabota

SouthernBoy

To GrayFox;

Depends upon what car and which engine in which you install a UDP (Under Drive Pulley).
My last car, a 2002 Altima SE, received a Frankencar WAI with Apexi filter, a full Mossy catback exhaust, and an Unorthodox Racing UDP. The intake was good for around 9 net HP to the wheels (along with 6 more lb/ft of torque). The exhaust added another 12 HP and 10 lb/ft of torque, and the UDP freed up 6.5 HP and 3 lb/ft of torque. These are bonafide numbers. Of course, the Altima engine is larger than the TL engine by 18 cubic inches and in a slightly lower state of tune so there's more room to grow.

Could you feel 6.5 HP and 3 lb/ft torque? Yes, you could.. but mildly. A slight increase in throttle response (a little more "touchy").

Now with my 1988 Mustang LX 32CID, I installed a UDP kit (only used two of the pulleys.. the crank and water pump pulley). These changes were good for 9 HP.

Turbowhat2

Hey, so if i have a subs and an amp thats pulling 600watts from the battery without a capacitor.... does it make sense if my fuel economy has decreased??? Because i was getting about 18-19 mpg before the subs and now im getting 16...

KJSmitty

Could very well be..
Your alternator would be working harder/more to replace the energy/amps taken from the battery. Thus more load placed on the engine.

-- Or the beat of the music is causing you to drive more aggressive... I know many songs still cause me to have a heavy right foot :-)

Like turbo mentioned, you could increase the size of your alternator pulley thus decrease the "draw" on the engine. But the alternator may then not keep up with the energy needs of your ride. If you're using the subs a bunch it may be something worth experimenting with,, given current gas prices .

In the old days, like Southernboy's 88 Mustang, the crank pulley was always significantly larger than all other pulley's. Decreasing the crank pulley was key for more HP but like Southernboy, the waterpump pulley is critical thus must be matched to the change to ensure proper cooling etc.

DOUBLE_M_I

So has anyone changed out the pulley on their TL? did it make a difference?