Throttle body size?? too big a bad thing?

Discussion in '94-95 5.0 - Specific' started by SaleenStang94, Sep 5, 2006.

  1. SaleenStang94

    SaleenStang94 Member

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    im looking to buy a 75mm tb and was told it might be too big. is 5mm that big of a difference? u can see the parts iv added in the sig. (94 GT) also, my itake inlet is 76mm C&L MAF, matching C&L cold air tube, stock tb, 75mm elbow. btw i would port the gt40 opening to 75. thanks for the imput
     
  2. Lightning Struck

    Lightning Struck Legend

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    over sizeing a Tb can cause a loss in power, because of the larger than necessary diameter of the TB it causes a loss in velocity of the air flow and as a result can cause a loss in hp and tq. For a 302 a 70mm is all that would be necessary unless in forced induction applications that may warrant a larger tb.
     
  3. Matt94GT

    Matt94GT Legend Retired Staff SN95 Supporter

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    I run a 70mm and mild HCI I took it off to put on my stocker because I heard his rumor and I deffently felt a power diffrence with the 70mm not on. But it does make sence, id go 75mm with what you have done IMO.
     
  4. 95KBGT

    95KBGT Legend

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    i run a 75mm TB on my KB just fine
     
  5. jimgt95

    jimgt95 New Member

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    I'll give you the same answer I posted for you on the corral. Optimally, you would use a 70mm. A 75 is a bit too big for your power level. Of course using it won't set you back 20hp, it's just not perfect for your application. And, down the road with say, a s/c, you will be right at home.
     
  6. 95KBGT

    95KBGT Legend

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    go with jim on this, he has always hit the nail right on the head with my problems with my kb
     
  7. SaleenStang94

    SaleenStang94 Member

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    thanks jim for the 2 posts 8) il def give it some thought.
     
  8. 95KBGT

    95KBGT Legend

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    its also nice to hear all that air getting sucked into the motor.
     
  9. Lightning Struck

    Lightning Struck Legend

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    oh yea I remember when I first put my JLT coldair on.............boy what a under the hood sound change that was ;D
     
  10. wytstang

    wytstang Well-Known Member

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    I'll go against the grain here and say the stocker is more then adequate. Why folks buy tb's based on the opening of the hole is just silly to me. You should choose a tb based on CFM the same way you would a carb (same concept). But don't take my word for it, take what Accufab has to say and come up with your own decision *BTW read what he says on page 2 about why Accufab doesn't make a tb for 94/95's (George Klass is Accufab)*
    http://bbs.hardcore50.com/vbulletin/showthread.php?t=26335&highlight=Cobra+intake
     
  11. SaleenStang94

    SaleenStang94 Member

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    wow that was a long discussion which was at times confusing, but mixed input's lead to some mixed impressions of what i should purchase. 75 might be too big? but it might not hurt? 70 might be perfect but less air = less power and as they stated the intake manifold is what will determine the cfm levels entering the motor, better flowing manifolds = more cfm and power. but.. the my 308 only produces a certain amount of cfm and the 75 might bring it down. :noes: having a gt40 manifold i could port the inlet to match the whole air intake setup i am running (76mm), except the tb. i think I'm gonna go with a 75 b/c this isn't overly aggressive and in a year or two Ill be purchasing a supercharger. any thoughts? did i interpret their conversation completely wrong?
     
  12. wytstang

    wytstang Well-Known Member

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    The entire thread was strictly N/A so as long as you are N/A take what Accufab is telling you, they could not get more air passed the EGR (94/95) then what the stocker could get by. When you go blown then upgrade as your induction system can not swallow 845 CFM from a 75mm tb n/a. If you want a custom cam you would go to Jay Allen, Ed Curtis for motors folks like Ronnie Crawford, CHP, DSS for a tb info I would go with Accufab. In other words go by what a pro says in their own field says as they have more in depth info then some one who isn't. Accufab live and breathes TB not a custom cam grinder or engine builder. AFR knows their heads better then Ed Curtis so if a vendor is telling you one thing and the manufacture is telling you that info is false, who would you believe??
     
  13. SaleenStang94

    SaleenStang94 Member

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    ah didnt see the second page to the posts, but yes this might be true that the 94 95s stock manifold wont allow more airflow in b/c of the egr but i have a gt40 intake (solves the problem) and no egr. it looks like someone has a tfs r intake and posted a similar follow-up. i wish he replied about that post. (but all aside i still think a 75 isnt a killer of hp, a 90 yes. the rest of my air intake setup is 76 so i dont belive this would harm my numbers).
     
  14. MeanGrn Gt

    MeanGrn Gt Well-Known Member

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    ya id say that 75 is too big and a waste of $$ unless your planning on boost in the near future. When i got the motor rebuilt on my old truck the mechanic decided to stick a 750 carb on the motor (400). I thought it was a little too big but they said no no it needs the 750 carb. Well a year later i said fuck em and stuck a 600 carb on it after gas went sky high and talking to my new mechanic. Throttle response and low end was much better. All around it was much better. It had to wind up with the 750 now she hauls ass immediately.(actually it feels like a dog now since i got the stang)
     
  15. Lightning Struck

    Lightning Struck Legend

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    the 75 may not be a killer of hp but it does not peak at the hp and tq level that a PROPERLY matched tb would.
     
  16. wytstang

    wytstang Well-Known Member

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    Wrong the EGR is not allowing more CFM on all intakes not just the stocker so problem solved to a piont, you still have an intake that can not utilize anything more then a 65mm (616 CFM) {94/95 cobra/gt40 intakes have an average flow of 198 cfm per runner} and even that is pushing it. IMO folks buy bigger tbs to say they have an oversized tb, I have yet to see a 302/306 than needed 845 CFM (75mm) @6500+ (N/A). Here is a CFM chart with a few popular long runner intakes
    [​IMG]
     
  17. SaleenStang94

    SaleenStang94 Member

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    this sounds right, i think im gonna keep the stock one for now. i ran out of fundings too so its gonna be a few weeks until i can afford a tb, and il prob get the gt40 ported when upgrading the tb.