G23 Boosted Build Ideas?

Discussion in 'Engine & Transmission Mods' started by Austin Dube, Mar 18, 2019.

  1. Austin Dube

    Austin Dube New Member

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    Thinking about a G23 custom build. Wondering if these parts would work out

    H22a dohc vtec head
    rsx 86mm pistons 4036
    h22a crank (50mm journals) (90.3 stroke opposed to 97mm f23 crank)
    k20 rods
    gt35 turbo
    and all the other bolt ons but these parts here are my main compatability concerns.
     
  2. Nam1911a1

    Nam1911a1 Well-Known Member

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    Seems like the G23 idea was a huge fad. A lot of work for little gains.
     
  3. BlkCurrantKord

    BlkCurrantKord Super Moderator

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    Couple things -

    You'll likely need to go slightly over bore on the pistons (86.5mm) to account for machine work and make sure the bores are perfectly straight and have the block line honed for the new crank and checked for clearances. Any machine shop should be able to do this. You're basically making a destroked engine.
     
  4. AntiArrhythmic

    AntiArrhythmic Member

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    Looks like compression would be about 9.8:1, and they would sit 0.045 below deck height. Those pistons hold a lot of power in K20's.

    The pistons sitting low in the bore might cause additional stress to the top of the cylinder on combustion. I definitely have never seen an oem engine with a piston that recessed. You could deck the block .045 and have 10.8:1 compression which is fine for e85 and boost. However at that point I'd be concerned about P2V clearance. The valve spacing and angle is probably different between the two engines. Even so it could be made to work with some clearancing, as long as it doesn't need too too much. (this would involve removing material from the piston.)

    The only way to know for sure would be to assemble the bottom end (Well just one piston/rod combo really). Then put the head on and clay the motor.

    It's definitely not something that could just be slapped together as it would involve machine work on multiple parts.

    Even if it works it's a lot of work for not a lot of benefit. Unless you have the parts and are experienced building engines and modifying parts, just turbo a stock H22 and save for the Mahle gold pistons and forged rods.
     
    Last edited: Apr 15, 2019

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