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Best sized throttle body and plenum

Discussion in '96-04 - 2V Specific' started by MDB919, Jul 6, 2014.

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  1. Jul 6, 2014 #1
    MDB919

    MDB919 New Member

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    Alright guys, I've done a little searching around with not a lot of luck. I'm getting ready to put the top end of my car together and need some advice. This is where I am right now.... I'm not sure what throttle body and plenum I should use. I've got a 1998 mustang GT 5 speed. It has a full PI head/intake swap, Cms stage 2 cams, shorty headers, off road x pipe, CAI, and it will be dyno tuned. What would be the best choice for me? BBK has that 78mm throttle body/plenum combo, but I'm afraid 78mm may be too big. But this is my first 2v, so I really have no idea. Any advice would really be appreciated.

    thanks,
    matt
     
  2. Jul 6, 2014 #2
    chris91

    chris91 Well-Known Member

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    I went with the Dragon Plenum and Pro Products 75mm TB. Not sure of numbers but they seem to do the trick.
     
  3. Jul 7, 2014 #3
    D3VST8R96GT

    D3VST8R96GT Well-Known Member

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    Plans for the car?

    Go big or go home
     
  4. Jul 7, 2014 #4
    MDB919

    MDB919 New Member

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    I'm trying to get 300 to the tires NA. I'm not sure if that possible with stock PI heads, but I'm going to give it a try. I might eventually do a plate nitrous system just for fun. But who knows.
     
  5. Jul 7, 2014 #5
    Ferocious

    Ferocious Legend SN95 Supporter

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    75mm will suffice.
     
  6. Jul 7, 2014 #6
    96blak54

    96blak54 Legend

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    You need to deck the block .030 and get a set of flat top pistons with valve reliefs...then youll be touching 340rwhp... :)
     
  7. Jul 7, 2014 #7
    nightfire

    nightfire Member

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    BBK 78mm plenum AND throttle. I'd advise against on an N/A 4.6 but you're cams are going to love the extra air.
     
  8. Jul 8, 2014 #8
    MDB919

    MDB919 New Member

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    That was my concern. That BBK 78mm combo is very affordable, but I don't want it to be too much and actually hurt the performance. I don't know if my cams are going to make it flow ENOUGH with unported heads. Ill probably just end up going with a set of 75mm's.
     
  9. Jul 9, 2014 #9
    nightfire

    nightfire Member

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    A 3mm difference is negligible....and you get a TB/plenum combo. It is NOT going to hurt performance.
     
  10. Jul 9, 2014 #10
    D3VST8R96GT

    D3VST8R96GT Well-Known Member

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    :popcorn:
     
  11. Jul 9, 2014 #11
    Caboose302

    Caboose302 Well-Known Member

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    You'll get close but I have ported heads and just barely cleared 300 rwhp. But then again I also only have stage 1 cams. I've always been told that 70mm is best for NA with a max of 75 for ported heads and bigger cams but I agree, I don't think 3mm will make a difference. Your biggest restriction is coming to be your upper plenum if you get a bigger TB.
     
  12. Jul 9, 2014 #12
    03DSGGT

    03DSGGT SN95 Supporting Member

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    I had full bolt ons and longtubes with stock heads, stock PI intake with the BBK 78mm piece, and CMS stage 2 cams and made 292 at the wheels. I'm thinking that with the bump in compression from the PI swap you will be knocking on the 300rwhp door...
     
  13. Jul 9, 2014 #13
    D3VST8R96GT

    D3VST8R96GT Well-Known Member

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    Well the 78mm is tb plenum combo.
     
  14. Jul 9, 2014 #14
    Caboose302

    Caboose302 Well-Known Member

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    I meant if he decided to go with a 70 or 75
     
  15. Jul 9, 2014 #15
    D3VST8R96GT

    D3VST8R96GT Well-Known Member

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    Ah I c.
     
  16. Jul 12, 2014 #16
    330CubeGt

    330CubeGt Well-Known Member

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    75mmishes is fine from a stock motor to a 600+hp motor no real need to go to a 78mm. Thats why you don't see many out there.
    The price diff to hp increase is not there.

    Sent from my SGH-T999 using Tapatalk 2
     
  17. Dec 14, 2014 #17
    mustanggt01

    mustanggt01 New Member

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    have you ever tried other plenums/throttle bodys?

    I have tried many setups between the stock, trickflow/75mm, stock plenum/70mm, and the BBK 78mm combo (1780). I must say you are wrong and honestly you lose a load of torque and gain a load of horsepower.
    From my experience the stock plenum with 70mm or trickflow/75mm combo is the perfect setup and you gain a bit of torque from both. When I went from the trickflow/75mm to that piece of junk BBK 1780 I was very disappointed and took it off in just 3 days and sold it on ebay. (01 gt) I have pulleys,K&N CAI, bama 93 tune,80mm maf, xpipe with high flow cats, welded in super 44's, 3.73 gears and back with the trickflow setup but I was using the 78mm BBK with these mods.
     
  18. Dec 15, 2014 #18
    DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    nice bump :)

    From the combo you posted I doubt you felt a difference when you switched between any of those combo's because the hp/tq increase/decrease is negligible from a plenum and tb on an n/a 2V. You are talking about differences of like 3-4 hp/tq between the best combo to the worst.

    Many dyno tests were done back when these cars were new and huge gains were not to be had from any combo.
     
  19. Dec 19, 2014 #19
    JerZeyStangz

    JerZeyStangz Well-Known Member

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    I have a 75mm Mac T/B and C&L plenum, lost a tiny bit of torque in low end range, but gained a bit in the mid-top end range on npi heads. Its a trade off until you go forced induction or put a set of powerful heads on or a combo of both.
     
  20. Dec 19, 2014 #20
    DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    Where you been hiding?
     
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