Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Throttle body size ..... is bigger always better?

Discussion in 'VT - VX Holden Commodore (1997 - 2002)' started by Ses, Sep 14, 2013.

  1. Ses

    Ses New Member

    Messages:
    60
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Sep 5, 2013
    Location:
    Shepparton
    Members Ride:
    Vt exec 5ltr s1
    Gidday im currently doing up a vt 5.0L wagon bit by bit and im looking at upgrading the throttle body as part of the process. I was looking at a 70mm one then came across a 90mm for around the same price. I was just wondering is it a case of the bigger the better or can this cause issues elswhere? Ive put on high flow cold air induction and a memcal chip im working on getting an exaust system made up right through because everything is just tired and stock standard. Id appreciate any feedback I can get as im pretty new to all this but loving it all the same :) cheers.
     
  2. commodore665

    commodore665 expat Saffa

    Messages:
    1,998
    Likes Received:
    11
    Trophy Points:
    38
    Joined:
    Dec 30, 2011
    Location:
    New Zealand via Cape Town
    Members Ride:
    2005 SV6 & Alfa Romeo 156 V6
    Hey man , I had on my old VX a bored out throttle body , and a host of other bits , growler intake , high ratio rockers , a tuned PCM , exhaust and headers , to be honest the gains were out weighed by cost , I got some extra gains , but would I do that again ? , probably not of course your V8 may benefit more than a V 6 , on a final note my SV 6 which is basically stock has more power than my VX had , even after the mods , point is how much are you willing to spend and what gains are you wanting to get .
     
    Last edited: Sep 14, 2013
  3. immortality

    immortality Donating Member

    Messages:
    10,498
    Likes Received:
    99
    Trophy Points:
    48
    Joined:
    Apr 15, 2006
    Location:
    Sth Auck, NZ
    Members Ride:
    HSV VS Senator, VX s2 Calais S/C
    70mm TB is where it's at for a standard banana manifold. I think it works even better on the VT 304's as they too have the little hump on one side of the TB behind the butterfly which is there to make the throttle opening more progressive like they did on the ecotec engines.

    Cold air intake is worth the money spent, I'd suggest the MACE item, you can also get the 70mm TB from them. They are a site sponsor, mention that you are a JC member and you'll get a discount.
     
  4. Ses

    Ses New Member

    Messages:
    60
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Sep 5, 2013
    Location:
    Shepparton
    Members Ride:
    Vt exec 5ltr s1
    Its funny you should say that mate the memcal and the cold air induction i put on today was from mase and the 70mm throttle body im looking at is their one.
     
  5. Ses

    Ses New Member

    Messages:
    60
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Sep 5, 2013
    Location:
    Shepparton
    Members Ride:
    Vt exec 5ltr s1
     
  6. Reaper

    Reaper Tells it like it is.

    Messages:
    6,189
    Likes Received:
    145
    Trophy Points:
    63
    Joined:
    Aug 15, 2004
    Location:
    SE Suburbs, Melbourne
    Members Ride:
    VZ LX8 Adventra, VP SS
    It's all about CFM. Calculate the max CFM your motor will use at max RPM for a start. Then think about how you will be driving your car. If it's a drag car then it'll spend most of it's time at max RPM so you will need something big. If it's a street car then 99% of it's time will be in the bottom 2/3 of the rev range in which case for throttle response and torque you will want something that in theory will be slightly small to the max "theoretical" CFM you need at top RPM. You will be giving away a few kw/torques for more down low/mid range.

    It's been a few years since I messed with them but from memory 90mm is far to big for an otherwise stock 5 litre, particularly street driven.
     
  7. Ses

    Ses New Member

    Messages:
    60
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Sep 5, 2013
    Location:
    Shepparton
    Members Ride:
    Vt exec 5ltr s1
    Yep id definatly be chasing the low down power it will be an every day driver I just want something that goes well and sounds good but is reliable at the same time. So the 70mm it is then thanks a lot for your input guys much appreciated.
     

Share This Page