Performance or high water flow pulleys?

Discussion in 'Classic Mustang Specific Tech' started by jcode68, Jan 20, 2006.


  1. jcode68

    jcode68 Active Member

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    I'm on the fence about which March pulley set to buy: the performance increase version (advertised 12-15% HP increase) or the high water flow for improved cooling. I'm running a 347 stroker, aluminum heads, Edelbrock alum water pump, stock radiator (for now) and will be adding electric fan. I live in the Northeast (MA) and only drive the car in nice weather. I know there are trade offs to both. I was leaning toward the high flow set because I want to avoid overheating problems completely, but wonderring if overdriving the water pump will shorten the life substantially. What are you guys runnig and why? :SNSign:
  2. 65ShelbyClone

    65ShelbyClone Founding Member

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    Lets put it this way: if your radiator cannot reject enough heat to keep your engine cool, more water volume wont help. If you're fine now and underdrives make it overheat, the the radiator needs addressing. Also, with underdrives you probably won't be able to run an electric fan unless you upgrade to a higher output alternator.
  3. 66HertzClone

    66HertzClone New Member

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    I have the underdrive pulleys on my stroker, 3 row original radiator, flowkooler waterpump, and the stock fan with the deep shroud. My temp gauge indicator has never even made it to the vertical position, tends to stay just at the edge of the operating range on the gauge.

    We have virtually the same equipment, I don't think you will have a problem with the underdrive pulleys.
  4. 302 coupe

    302 coupe Founding Member

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    only an idiot would expect a 12-15% hp increase, if you're buying them for a performance boost you will be disappointed. You're only turning the water pump and alternator, correct? Maybe you have AC and power steering, I don't know. You might, with extreme luck, gain 2-3 hp. On the other hand, you'll have a nice looking set of pulleys, if you're into the bling bling stuff. There just isn't much belt drag on this old stuff for underdrive pulleys to make a big difference, even on fox body cars with pulleys galore they're only good for 5-6 hp.
  5. xoxbxfx

    xoxbxfx Founding Member

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    pulleys are for bling bling not performance. Just get a serpentine setup from a fox and be done. The march setup is the biggest ripoff ever
  6. jcode68

    jcode68 Active Member

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    Thanks for the comments guys. I fully realize that the advertised 12-15% HP increase is BS, but am sure there is some advantage, even if minimal. I was leaning toward the high flow setup because I would rahter have a cooler running engine than an additional 5-6% Hp on top of the 400+ I'm already making. I was more looking for comments from people who experienced any wear/failure problems with their water pump as a result of overdriving it with the high flow pulley. I think I'm going to go the high flow and have no regrets with a cooler running engine.
    Regarding the "bling" comments - well everybody is entitled to their opinion. I enjoy working on and driving my stang, but I also enjoy detailing it and having something that looks jaw dropping good. I have taken the time to detail things under my hood, so I'm not about to slap on factory brackets and pulleys. I'm thankfully at a point in my life where I can afford to do some things to this car that I couldn't the first time around. So damit, I'm gonna :nice:
  7. iskwezm

    iskwezm Advanced Member

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    i have used underdrive pulleys before on a few cars and will NEVER use them again or recommned them. I use stock chromed pulleys and big radiator and havent seen over 190* with my blown stroker and wouldnt use anything else.
  8. 65ShelbyClone

    65ShelbyClone Founding Member

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    One place underdrives do have a use is on an engine that spins high rpm for extended periods like road racing. If the pump spins too fast, the water will cavitate and not only induce corrosion, but not move as fast either.

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