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Thread: A question on throttle bodies

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    Spanner Monkey

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    A question on throttle bodies

    Hi everyone. Sorry to be a pain but I have a question regarding throttle bodies. I rather like the design of the raceline direct to head ones but there is 45 and 48 mm options. What have people here used and with that results? My car is an mgb weighing roughly 875 kg, the engine is 2.0, Kent dtec35 cams, supertech pistons and K1 rods, 12.5:1 compression ratio, lightened flywheel and fully balanced. I hear things of up to 270 bhp with these kind of components but I want the car "driveable" too.

    Thanks

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    Re: A question on throttle bodies

    throttle body size has little effect TBH, if you have bodies which are very big the throttle tends not be be as progressive, because a slight pedal movement at small openings gives a lot more air to the engine.

    ive driven cars with oversize bodies all that happens is you adjust and dont tend to make as big a movement on the pedal, or if you are already at a fairly big throttle opening the last bit of movement doesnt do much

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    Re: A question on throttle bodies

    http://www.jenvey.co.uk/faq/general-faq

    The Jenvey site gives some rule of thumb numbers that might help -

    This suggests for a 2.0l Duratec running say 250hpat 8k revs you need 45mm

    Cosworth do a 255hp 2.0l but the throttle bodys not stated ut looks like 48mm
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    Bodger

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    Re: A question on throttle bodies

    your going to make me want more power in mine, what box have you got again?

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    Re: A question on throttle bodies

    Ill be mostly using it on road so looks like 45's then. Thanks guys!

    its a type 9 box with BGH Geartech bearing upgrade but ill be upgrading it with lubrication mods too to cope with high revs.

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    Re: A question on throttle bodies

    Hello again itsawindupuk. How you getting on with that water outlet?

    I was advised 42mm Jenvey's on a hot Pinto engine. The guys at Jenvey told me that you always size a TB a little less then the equivalent carb size on the same engine. He said never be tempted to go too big.

    Sounds like that MGB is going to be awesome!

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    Tyre Kicker

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    Re: A question on throttle bodies

    I would advise 48's the 45s are proving to be to small with even a stock hiport head

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    Re: A question on throttle bodies

    Hi beeRS, haven't attached it yet as I'm going to make an o-ring sealed pipe for it. Also been doing bodywork. I spoke to a guy at raceline who said 45's but generally getting mixed answers. Confused.com

  10. #9

    Re: A question on throttle bodies

    Quote Originally Posted by itsawindupuk View Post
    Hi beeRS, haven't attached it yet as I'm going to make an o-ring sealed pipe for it. Also been doing bodywork. I spoke to a guy at raceline who said 45's but generally getting mixed answers. Confused.com
    If its any help my Duratec mapped by Steve at Track & Road made 268.1 bhp at 8413 rpm and 184.9 torque which peaked at 6787rpm using 45mm throttle bodies.

  11. #10

    Re: A question on throttle bodies

    Will yours make the same power using 45s? all depends on the spec and build quality at the end of the day

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    Spanner Monkey

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    Re: A question on throttle bodies

    Probably not then as I built the engine and ported the head myself. But I'd still be happy with 150 bhp.

    Eric are your throttle bodies direct to head or on a manifold? What length trumpets did you use?

  13. #12

    Re: A question on throttle bodies

    If you use those cams and pistons you should see a easy 240+ bhp even if you ported the head yourself. My throttle bodies are the bolt to manifold type, the jenveys came from Chris at Raceline the manifold is a Jenvey item from Burton Power, ram pipes are 40mm.

    Last edited by eric; 17-01-2017 at 19:51.

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