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Thread: can you have a throttle body thats to big?

  1. #1
    jzx100 fan boy Domestic Engineer slide86's Avatar
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    Default can you have a throttle body thats to big?

    as the title states. i have a 90mm throttle body here that i was going to use on my GZE. but i have been thinking that maybe its going to be too big.

    with the size that it is, when opening the throttle a little, it would be the same as opening it a lot if i were using the factory body. if you get what i mean.

    by having one really big the amount of air going in on partial throttle woiuld be alot. would this cause a harsh on/off throttle down low?

    ideas and inputs please?
    Quote Originally Posted by The Witzl
    Please visit here, they will have all the answers you need for this "conversion" - www.hot4s.com.au

  2. #2
    Toymods Pimp Chief Engine Builder Norbie's Avatar
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    Default Re: can you have a throttle body thats to big?

    Yes, a larger throttle butterfly will give you a more sensitive accelerator pedal. In extreme cases this could make the car pretty hard to drive!

  3. #3
    jzx100 fan boy Domestic Engineer slide86's Avatar
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    Default Re: can you have a throttle body thats to big?

    thats pretty much what i thought. i think this one is a bit big for a GZE.

    i still have a holden 304 and v6 throttle body to choose from
    Quote Originally Posted by The Witzl
    Please visit here, they will have all the answers you need for this "conversion" - www.hot4s.com.au

  4. #4
    Current UZA80 owner Chief Engine Builder JustCallMeOrlando's Avatar
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    Default Re: can you have a throttle body thats to big?

    WTF is the 90mm throttle from?
    Teh UZA80 - Project Century - Remotely p00'd by association

  5. #5
    jzx100 fan boy Domestic Engineer slide86's Avatar
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    Default Re: can you have a throttle body thats to big?

    nissan infiniti.

    i can fit my fist into it. NO BULLSHIT.

    ill probably sell it now anyways.
    Quote Originally Posted by The Witzl
    Please visit here, they will have all the answers you need for this "conversion" - www.hot4s.com.au

  6. #6
    jzx100 fan boy Domestic Engineer slide86's Avatar
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    Default Re: can you have a throttle body thats to big?



    thats my fist in it! hahahahahahahaha
    Quote Originally Posted by The Witzl
    Please visit here, they will have all the answers you need for this "conversion" - www.hot4s.com.au

  7. #7
    I make people cry Chief Engine Builder Draven's Avatar
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    Default Re: can you have a throttle body thats to big?

    for a 4a-gze?!
    maybe just a little overkill
    from memory, upgraded JZA80s use 90-100mm throttle bodies
    http://www.toymods.org.au/forums/showthread.php?t=7465
    Quote Originally Posted by xero View Post
    and of course campbell newman's completely fucking everything he touches so badly that he should be called dick fingers.

  8. #8
    Sucks to be a Domestic Engineer YelloRolla's Avatar
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    Default Re: can you have a throttle body thats to big?

    Like has been said, 90mm is extreme overkill for your 4A. I use a 50mm throttle in the KE20. I believe that smaller throttles offer better airspeed.
    One calc that I have seen regarding throttle size is not to exceed 300ft/sec.
    YelloRolla's KE20 1/4mi = 11.32 @ 119mph @ 22psi on slicks
    12.44 @ 113 mph on 165 wide street tyres
    210rwkw - not bad for a smelly 3TGTE running pump fuel.

  9. #9
    Junior Member Grease Monkey
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    Default Re: can you have a throttle body thats to big?

    You want your airflow at desired conditions to be around Mach 0.6.

  10. #10
    Sucks to be a Domestic Engineer YelloRolla's Avatar
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    Default Re: can you have a throttle body thats to big?

    Quote Originally Posted by pilot
    You want your airflow at desired conditions to be around Mach 0.6.
    Quite an interesting air speed that you've mentioned there.

    Given that airspeed (approx 660 ft/sec) then the 4A GE will require a single T/B of around 27mm diameter (assuming 110% VE and 7000RPM). Now that's a small throttle plate.

    Have I missed something?
    YelloRolla's KE20 1/4mi = 11.32 @ 119mph @ 22psi on slicks
    12.44 @ 113 mph on 165 wide street tyres
    210rwkw - not bad for a smelly 3TGTE running pump fuel.

  11. #11
    User Conversion King
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    Default Re: can you have a throttle body thats to big?

    one way to avoid the sensitivity of a big TB is to use a guide that is in the shape of and involute.

    so at idle, the distance from the pivot is high and so TB rotates slow relative to accelerator depression. then as you depress the throttle poedal more, the distance to pivot decreases
    hello

  12. #12
    Estranged Member Chief Engine Builder mullett's Avatar
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    Default Re: can you have a throttle body thats to big?

    ...but there's only so much air that an engine can consume. I'd hazard a guess that even at full noise, you'd make the same power on 50% throttle as full throttle with something that big....

    RM.

  13. #13
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    Default Re: can you have a throttle body thats to big?

    a bigger throttle body (which usually means bigger piping) will decrease air velocity at high rpm.

    high air velocity means you will get a pressure drop through the piping.

    pressure drop = less air entering engine = less power
    hello

  14. #14
    anti blasphemy ! Carport Converter
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    Default Re: can you have a throttle body thats to big?

    when i put my big t/b on my gte i had to change the way i drive as such, id have to only touch the throttle a little to vary the revs(once spinning).
    a big throttle body opend a small amount is like a small t/b opend half way.
    if i were to make one it would be a duel stage like the mechanical secondarys in a carby, but if for dragging bigger is better.

    pressure drop = less power
    more pressure = more power
    more pressure more flow = more more power
    i dont have a funny or cool signature.

  15. #15
    User Conversion King
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    Default Re: can you have a throttle body thats to big?

    find a TB with one of these

    hello

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