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Discussion Starter · #1 · (Edited)
Hey people,

I was thinking of getting either an underdriven or a lightened stock size crank pulley.

I was advised to get the stock size one and keep the money saved on the belts and extra install time to spend on something else ,as there would not be that much difference.
Is there much of a perfromance gain difference between the two although i know it will probably give me about 5 hp aprrox for either one?

What do you think

Mods so far mrt full exaust, pde up pipe. samco intercooler hose set,and short shifter.
 

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under drive pulley

Hi there....


Maybe I can help. Rather than sit here an ponder how much of a horsepower difference there is between the two, I am going to use your estimate of 5hp.

The difference in cost and install time for a underdrive pulley and a lightened stock diameter pulley is negligable. An underdrive pulley and belts will most likely cost you an additional 50-75 dollars, and 10 minutes of install time.

If you were to offer most anyone on this forum 5 hp for 50 dollars and 10 minutes they would not blink an eye before springing into action. You have to consider dollar value vs. power increase. Here you are talking about 5hp for 50 dollars. Thats an increase of 1hp for every 10 dollars spent.

Now consider a modification like a turbo back exhaust system. Generously, lets consider a 25 horse power gain for 1200 dollars. Now we are talking about one horse every 48 dollars. Pound for pound the under drive pulley offers a lot more benefit.

Am I saying here that an UD pulley is a better mod than an exhaust, no way. But I am saying that the supplied reasons for sticking with the stock pulley should probably not be enough to keep you from just getting an UD pulley and taking advantage of that extra couple horses.

Just food for thought. Hope this helps!


Take Care,
 

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i know vishnu offers an underdrive pulley for $172 dollars and they claim no loss of electrical power and a gain of 5-10hp
 

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Polaris-

Either one is going to give you the HP gain by reducing rotational inertia in the drivetrain.

The real question is to underdrive or not. Garret did a great job explaining the benifits of swapping out the stock pulley. If you go with a pulley that is the stock size but lighter, such as the TB Racing model, you get the gains of the lightened pulley without the electrical drawbacks.

With an underdrive pulley, you might not notice any loss of power unless you put extra drain on the electrical system. In other words, if you toss a huge amp in the trunk, you'll see some headlight dimming. This could also simply be a shortcoming of the stock electrical system, as the headlights on my old Outback used to dim when the bass hit on my 200 watt amp.

So basically, I've just wasted about five minutes of your time without providing any sort of concrete evidence for leaning one way or the other. And you can never get those 5 minutes back....ever :D
 

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As Dave implied; I think it depends upon your other vehicle modifications and exactly what you expect of the pullies.

Given my modifications, I personally wouldn't underdrive as I have a significant number of components that increase the net electrical draw. Also my PossumLink ECU can be a little fussy regarding electrical load fluctuations.

On the other hand, if my vehicle were stock or near so, I would definitely want to extract every last horsepower for my dollar and so I would use underdriven pullies in that situation.

-Pace
 

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hyper said:
anyone one else have some opinions?
I don't know where you live, but down here in Houston it gets pretty freakin' hot. Penguinking has one, and he says his A/C sucks now. That's something to consider for ya:D
 
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