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What size supercharger pulley

Discussion in '1994-2004 V6 Mustang Tech' started by 20003.8stang, Mar 22, 2017.

  1. 20003.8stang

    20003.8stang Member

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    I am doing a m112 build on my 3.8 the supercharger has a 2.8 pulley on it now I want a bigger one any opinions on what size I should do I found a 3.4 on eBay and a factory 3.65. American muscle had bolt on ones up to 3.0 and pulley boys has quick change ones and press on up to 3.2". The one on it is a bolt on one with 4 bolts.
     
  2. JTsStang

    JTsStang Boosted V6

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    If its a setup you're going to keep go with the quick change. Why are you trying to lower boost?
     
  3. 20003.8stang

    20003.8stang Member

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    Because 2.8 is pretty small I didn't want to be that hard on the blower and engine. Eatons are really hot to start off with and I won't have meth right away so I figured the 2.8 would create more power rubbing heat than id want.
     
  4. Phil II

    Phil II Cone Destroyer Staff Member

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    I ran a 3.1" blower pulley with an under-drive crank pulley. That underdrive is essential for getting a decent ratio.
     
  5. 20003.8stang

    20003.8stang Member

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    Could you explain what you mean by decent ratio? Wouldn't the underdrive lower the boost? I have a small crank pulley on hand so I'll use it if it's beneficial. Wouldn't it lower the psi if so by how much? A pound?
     
  6. 20003.8stang

    20003.8stang Member

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    Sorry I retract my previous question. I'm assuming you mean the v6 crank pulley is bigger than the Cobra so it is turning the supercharger much faster so the underdrive pulley is closer to the same size
     
  7. Phil II

    Phil II Cone Destroyer Staff Member

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    The pulley ratio for a terminator is a poor reference for a v6 setup. Big differences in cylinder head flow and intercooling. Its a very good idea to under drive the blower.
     
  8. 20003.8stang

    20003.8stang Member

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    Okay that makes sense. What's size pulley would you recommend I was thinking 3.4 would that still be like 10-11 psi?
     
  9. Phil II

    Phil II Cone Destroyer Staff Member

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    I used the ASP under drive crank pulley and a 3.1" blower pulley, 11# of boost. Ported heads, cam, stroker...its not exacy apples to apples.

    Start with a big blower pulley, work your way down. The limiting factor is heat as the compressor becomes less efficient.
     
  10. 20003.8stang

    20003.8stang Member

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    Okay I'll start with underdrive pulley and 3.4 blower pulley. I'll ask ssm what cam is best for me.
     
  11. Phil II

    Phil II Cone Destroyer Staff Member

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    218/224 lsa 112, ask for it advanced 5 degrees not 4.

    Closing the intake valve between 35 and 40 degrees ABDC will net the best torque curve and average horsepower.
     
  12. 20003.8stang

    20003.8stang Member

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    Thank you! Why is that? Just gets to maximum amount of air into cylinder before it closes? Having it advanced 5 degrees moves the intake love making out close 5 degrees later? Sorry for the questions I just want to understand why the best I can
     
  13. Phil II

    Phil II Cone Destroyer Staff Member

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    Research valve or camshaft timing. It will help a lot.

    Advancing the camshaft closes the valve sooner. ABDC is after bottom dead center. The closer the intake valve closes to bottom dead center, the greater the swept cylinder volume. That helps peak torque but inhibits peak power.
     
    Last edited: Mar 30, 2017
  14. ProjectVicky

    ProjectVicky Wrench Monkey

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    Phil II, do you have any suggestions for reference material that details how camshafts affect fuel economy/ performance? From what I understand through online searches, a bigger cam helps in a higher rpm range but causes idle issues, a smaller cam does not balance high rpm power well but helps with lower end torque. Is there anything that can help me understand its affects on mpg?
     
  15. Phil II

    Phil II Cone Destroyer Staff Member

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    Most of the camshaft articles are about making more power. An oem camshaft is meant to do all things with some balance. These usually feature short duration, early IVC, and lift profiles tailored to what the cylinder heads can support.

    Overlap can kill fuel economy, unless fuel injection timing is altered after EVC.