Underdrives

94coupe · Jan 18, 2014

ive been doing a little research on underdrives.....with mixed results.....its my daily driver in the city....but hits the track on weekends.....are they worth putting on? what about charging and cooling?
thanks cam.

Noobz347 · Jan 18, 2014

No. They are not worth installing. They usually cause more issues than benefit. Best case scenario is that a set of pulleys are 20% under drive. That works out to be about 6 HP at the wheel at MAX!

You wanna spend money on a cheap upgrade? Ditch the clutch fan and install an electric one with controller.

Want even more? Replace your belt driven water pump with a Mazier (sp) electric pump.

Both of those mods are about the same cost per HP and neither causes cooling or charging issues.

revhead347 · Jan 18, 2014

94 Mustangs don't have clutch fans, and there is almost no bigger waste of money on a street car than an electric water pump. You want to talk about causing problems. The underdrive pulleys do have a minimal yield. You can have problems if you underdrive an old alternator too much. Generally on a car with a decent alternator they don't cause any problems. The performance gains have been a topic of discussion for a long time. Even the most positive speculations aren't that great. There are better places to spend your money.

Kurt

Noobz347 · Jan 18, 2014

Not that the OP should take the same path but I've been running my electric water pump for roughly 30K miles though a DCC controller. Not even a hiccup. What even nicer is that is that it continues to run to a predetermined temp after engine shutdown.

Arguably, it can be done wrong (and has been). Under drive pulleys on the other hand are nearly always wrong and cause more in issues than what you gain in HP.

revhead347 · Jan 18, 2014

I run an underdrive crank and alternator pulley. I think under driving the water pump causes too many cooling problems. Most of the people I know who tried to run an electric water pump end up stranded on the side of the road somewhere. Not to say everyone is going to have that experience, but it happens often enough that I just don't recommend it. If it was a track only car, that would be a totally different story.

Kurt

Noobz347 · Jan 18, 2014

Like many things these days, I see folks attempting to run the cheapest, prettiest, POS imported from China and purchased on Ebay.

Like you, I've seen a LOT of those units fail. I also see a good share of wiring hack jobs (i.e. 30+ amp pumps run through a circuit that gets power from the ignition switch). Those hack jobs are also a fail.

The pump I run is the one with the idler pulley (so no rerouting of the serpentine belt). The controller regulates voltage to the pump and shuts it (and the fan) off 20-ish seconds after engine shut-down (sometimes longer on hot summer days). You know... just long enough to equalize things in the engine bay.

I like the setup. I'm considering doing the same thing on the 89 that I picked up for the kids.

chaos254 · Jan 18, 2014

I had ran all the asp underdrive pullies for awhile but now all I run is the crank pulley.

revhead347 · Jan 18, 2014

I agree on the electric water pump. Most of it is just bad pumps and poor installations. A good pump installed well is expensive. Better places to spend your money.

To get back on topic, I think that's just about how it always works out with under drives; you buy a set of 3, and after a few months there is only one or two of the pullies left on the car, and you've spent a ton of time sizing belts to get those one or two pullies to work.

Kurt

jozsefsz · Jan 18, 2014

Nickel & dime waste of time... save up for some mods you'll actually feel without trying to fool yourself that it feels quicker. H-C-I for N/A or Forced Induction. I probably spent more on money-wasters trying to eek out an extra 5hp than I spent going turbo once I got sick of that game. And I agree with the general consensus, not only will they not give you anything you'll notice, they'll give you problems you don't want in a daily driver.

joetrainer31 · Feb 1, 2014

94coupe said:
ive been doing a little research on underdrives.....with mixed results.....its my daily driver in the city....but hits the track on weekends.....are they worth putting on? what about charging and cooling?
thanks cam.

Please for your sanity, DON'T DO IT. Noobz347 is so right when he says that they cause more problems than they are worth. Besides, used OEM pulleys are expensive and hard to find for a reason.

I just took off the under drives (part of the SVO-GT40 package), bought OEMs, installed them and it runs so much better. Its stronger, smoother, runs cooler, and doesn't have disco headlights.

94Blue302GT · Feb 11, 2014

I was going to say the same as above. Perhaps only the main crank pulley is all you would want to do there.
The electric water pump would probably save more, but I personally am scared of them. I guess i'm old school.
Look into a set of heads if you haven't. Some good aluminum heads makes the 302 insanely different. Best bang for the buck without going forced induction IMO

'94ChickStang · Mar 14, 2014

Only do it if you are doing other upgrades at the same time. I did mine when I did my h/c/i since I knew my tune was going to bump up my idle, which solves the charging issue.

The only upgrade I ever felt any noticeable difference after (without adding fuel, air, or spark) was swapping gears. If you haven't done that, spend your money there. All of this talk about electric fans and pumps will get you nowhere.

Underdrives

94coupe

Noobz347

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revhead347

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Underdrives

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