Throttle body and Plenum upgrade on 2004 GT.

Discussion in 'General Tech' started by PHATSPEED7X, Feb 22, 2015.

  1. PHATSPEED7X

    PHATSPEED7X New Member

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    Hello. I'm looking at ordering a new larger throttle body and plenum for my 2004 GT. It has the stock 4.6L V8, and the only mods I currently have for the car are exhaust (Pypes off-road H pipe, M80 mufflers), and a Cold Air intake. I've been looking at the BBK assemblies that incorporate both the throttle body, and plenum into one unit. I see they offer it in two different sizes (73mm, and 78mm). Everyone thinks the old saying "bigger is better", but I've seen reports of the 78mm unit actually hurting performance on lightly modified motors. After finding that out I think maybe the 73mm model might be a better choice. I don't plan on adding forced induction to this motor (that's where a 78mm TB would shine).

    I can get the 73mm (Part #17801) brand new in box for around $200 from an online supplier I found. Worth it? Or can HP be found else where with that same money?
     
  2. Cpotts13

    Cpotts13 Well-Known Member

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    Yes. Bigger isnt always better. For stock application I would go 70mm or close to that. I noticed a slight increase in throttle response but for the cost i'm not to sure its a good mod.
     
  3. PHATSPEED7X

    PHATSPEED7X New Member

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    A buddy said I'd be better off with a tuner first. I will eventually have both mods done to the motor.
     
  4. 96blak54

    96blak54 Legend

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    Could get a truck 5.4l 70mm throttle body, swap it out.
     
  5. PHATSPEED7X

    PHATSPEED7X New Member

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    I decided to keep the stock throttle body and plenum for now. Maybe later this spring I'll change it up.

    Current setup...

    [​IMG]

    Airaid cold air intake. Poweraid throttle body spacer.
     
  6. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    look for them used I have seen them half price when guys swap on superchargers.
     
  7. ttocs

    ttocs Legend

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    How big is the opening on the plenum? I ask because I was surprised to take my pushrods intake off and measure that it was only 70mm. I thought this was a little strange since everyone I know with a pushrod that upgrade the tb goes to 75mm.
     
  8. PHATSPEED7X

    PHATSPEED7X New Member

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    I didn't measure it when I had things apart. I've been driving the car this week since I installed the new parts. Car seems to pull harder now. I also installed a Steeda Tri Ax shifter. Getting use to that also. Overall very happy.
     
  9. PHATSPEED7X

    PHATSPEED7X New Member

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    Just ordered the BBK 78mm throttle body plenum assembly for my Mustang. Got a deal on one.
     
  10. 96blak54

    96blak54 Legend

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    Nothing wrong with a deal. Post picks of the install bro!
     
  11. Burninriverdiver

    Burninriverdiver Well-Known Member

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    Heck yeah that's why I got mine, dressed up the engine a little and was on sale. I did pi cams, pi manifold and a tuner at the same time as the tb/plenum upgrade, so I can't tell you how much it helped overall. But my car pulls much harder with all of the above added to the npi motor. The thing I like about the bbk is the noticeable whistle it makes under throttle lol
     
  12. chris91

    chris91 Well-Known Member

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    Cant go wrong with the BBK setup. What are the future plans for the car? You might lose some low end with it being a 78mm.
     
  13. PHATSPEED7X

    PHATSPEED7X New Member

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    After supplier issues and my BBK 78mm throttle body plenum assembly being placed on backorder through bbk I ended up cancelling my order.

    I reordered the SVE 75mm throttle body and plenum combo. Hopefully it ships Monday.

    Customer service from late model restoration was excellent and this wasn't a fail from them. BBK on the other hand...
     
  14. PHATSPEED7X

    PHATSPEED7X New Member

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    Finally after nearly a month after I ordered the BBK and then cancelled it I got my SVE 75mm throttle body and plenum combo instead. Installed it in about 30 minutes. I'm happy with it. Pulls harder than the stock unit that's for sure.

    Before

    [​IMG]

    After

    [​IMG]
     
  15. 96blak54

    96blak54 Legend

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    Oh yea! Looks good, nice work! Was you making a bunch of engine rev sounds while you worked?....lol
     
  16. PHATSPEED7X

    PHATSPEED7X New Member

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    I'm really impressed how this really woke the motor up. Everyone says a 75mm throttle body is too much for a n/a motor. I think it's just right.
     
  17. ttocs

    ttocs Legend

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    well don't keep us hanging... Get your friend with his best fossil watch and you with yours to get some times on this *****!:laughing4:
     
  18. PHATSPEED7X

    PHATSPEED7X New Member

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