B-series TB on D-series intake manifold

wagodizzlewagodizzle Council Member and EDM expert
in Engine & Drivetrain
i have a D15B2 with an MPFI swap using all civic Si intake parts. i was wondering about one thing though.. i know the B-series throttle body fits on a D-series manifold, but is it bigger then a D-series? so if i swap out my D TB for a B TB will i get any HP gains at all? or possibly use it later on on a Skunk2 intake manifold....

input?

Comments

  • pLaYbOipLaYbOi Wagonist
    you'll gain some power using the B series TB but wont see any true gains till you port match the TB to the intake manni and the intake manni to the head.

    I'm currently putting the same setup together pretty much but i have a KBB TB that is the same size as the 1st gen Skunk2 IM i have but i still have yet to bring the head to a shop and have them port match the head to the IM.
  • wagodizzlewagodizzle Council Member and EDM expert
    mkay. i can get TB's for $20 over here i was just wondering if its worth it. so far im undecided as to what i wanna do as far as engine, i thought about building my D but at the same time a B16 or H22 would be pretty dope. more then likely the H22. its going to be at least a year or two before i do any swap so should i just semi-build my D till then with just bolt ons like AEM fuel rail, Skunk2 IM etc?
  • eldonciv777eldonciv777 Wagonist
    Out of curiousity, why would you buy a fuel rail when the stock one works fine? Save your dough for the swap and do it faster (except for exhaust and other such transferable parts).

    On d-series.org I've heard it claimed that the throttle body will not be the limiting factor unless you have a pretty decent all motor build, just food for thought.

    Also on portmatching, won't that interrupt the velocity of the air as much as it will help? You're going narrow > bigger > narrower/valve. By going narrower to larger you will lose velocity. I've also heard it said that the little step acts like an anti-reversion feature. I don't know, just something to think about.
  • eldonciv777eldonciv777 Wagonist
    Just found this on honda-tech, it was posted by Maxbore.com (he bores throttle bodys).
    OBD0 D series (1991 or older) Tbs are not compatible with B series TBs.
    OBD1 D series (1992 or newer) Tbs share the same bolt pattern as B series
    I think you could get just some of the screws to secure the TB, but That's just not the right way to do it. I don't think the Tb bore and the manifold opening will match.

    I thought this was the case, but didn't want to say so until I looked.
  • wagodizzlewagodizzle Council Member and EDM expert
    yeah you're right also im not going to be boosting so there is really no need to have more fuel flow.

    eh, i just like shiny things :mrgreen:
  • eldonciv777eldonciv777 Wagonist
    Who doesn't :lol:
  • pLaYbOipLaYbOi Wagonist
    eldonciv777 wrote:
    Out of curiousity, why would you buy a fuel rail when the stock one works fine? Save your dough for the swap and do it faster (except for exhaust and other such transferable parts).

    On d-series.org I've heard it claimed that the throttle body will not be the limiting factor unless you have a pretty decent all motor build, just food for thought.

    Also on portmatching, won't that interrupt the velocity of the air as much as it will help? You're going narrow > bigger > narrower/valve. By going narrower to larger you will lose velocity. I've also heard it said that the little step acts like an anti-reversion feature. I don't know, just something to think about.

    I believe the point of port matching is to keep the velocity consistent. if you'd imagine, putting on an aftermarket IM with a larger inlet than the TB outlet, the flow of air would then be disturbed from the difference in diameter between the two openings. So i guess imagine blowing out of a straw with a plate at the end with a hole smaller in diamter than the straw itself verses blow out of the same straw with the plate's hole being the same size.

    Am i gettin you right?
  • Mista BoneMista Bone Wagonist
    D16 MPFI TB is plenty big enough for a D15, even one putting out about 40 whp over stock.
  • eldonciv777eldonciv777 Wagonist
    I believe the point of port matching is to keep the velocity consistent. if you'd imagine, putting on an aftermarket IM with a larger inlet than the TB outlet, the flow of air would then be disturbed from the difference in diameter between the two openings. So i guess imagine blowing out of a straw with a plate at the end with a hole smaller in diamter than the straw itself verses blow out of the same straw with the plate's hole being the same size.

    Am i gettin you right?

    You're right about the throttle body, I would try to smooth out the step there. For some reason my mind jumped to portmatching the intake manifold at the gasket/head, which a lot of people do. So my rant was mainly directed at that, not at port matching the tb. Sorry for the confusing off-topic rant...
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