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Vtec head on a hf block?

Discussion in 'Engine Building' started by drpenguin, Nov 23, 2004.

  1. drpenguin

    drpenguin Senior Member

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    I have a 89 crx. It has a stock d15b6 in it. Could i put a zc vtec head on it?
     
  2. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    As long as the original head had 16 valves, yes.
     
  3. erastusboy

    erastusboy Junior Member

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    hf's are multipoint so you dont need to switch that, but i dunno if the head would fit cause the bore size is different (like 84.5 for the d15 and 90 for the d16). if you really wanna swap heads you can switch to a dx head, theres an article to show you what to do on here int he swap article section
     
  4. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    :newbie:

    The HF apparently had both DPFI and MPFI setups. I do know that the HF engine I had sitting in my garage was MPFI though.

    http://hybrid2.honda-perf.org/tech/engine.html
     
  5. Bl6CRX

    Bl6CRX Senior Member

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    BAWAHAHAHAHA!!!! Don't you feel smart hahah, DXs are dual point, HF/Si's are mpfi, well at least every HF I have ever seen or heard of.
     
  6. drpenguin

    drpenguin Senior Member

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    Yeah but putting a DX DOHC head on my engine would cut its life to about 85000 miles. I was told that the head would double my hourse power. Up from the 56 i have to around 110 or 112. As much as i would love a DOHC head vtec is just soo much cooler in my book. Nothing like hitting that 6200 rpm's and hearing that scream!!!!!!!!!!
     
  7. drpenguin

    drpenguin Senior Member

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    The car only has 8 valves is that gonna be a problem?
     
  8. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Just make sure your pistons have 4 valve reliefs each and you should be fine.
     
  9. drpenguin

    drpenguin Senior Member

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    How do i know if i have multi point or dual point? Im assuming that multi has 4 injectors and dual only has 2? if so i have multi!
     
  10. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Yes, then you have MPFI.
     
  11. AllMotorMonster

    AllMotorMonster Senior Member

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    Maybe i'm out there, and I admit I don't know crap about the ZC engines, but...

    since when did the ZC engine have VTEC???
     
  12. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Supposedly when the D16Z6 got stamped with "ZC" in Japan from 92-95. I've never seen one before though, so I really don't know for sure if it exists.
     
  13. sohcslammer

    sohcslammer Senior Member

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    Have seen it with my own eyes. It confused the hell out of me the first time. My buddy had one in his EG coupe.
     
  14. Freaze_or_buRn

    Freaze_or_buRn Junior Member

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    ok this is all here say, but ... I have heard that you can swap IF and only IF you swap the pistons aswell, you only have 8 valves on you hf, and you only have 8 valve reliefs on the pistons... if you swap the si pistons you'll get a f*cked up CR (like 14) and you'll go Hella fast... but not for very long. I also have a hf, and thought of giving it one last bit of glee before my swap takes place. but I'm to lazy. give it a wirl and tell us how (long) it goes...

    on and you can't put a zc dohc head on, you could put a sohc zc(jap spec d16a60 or zc vtec (jap spec d16z6) on but.... just buy one of those cheap as d15b vtecs or a usdm z6 and be done.
     
  15. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Actually, no. If you put in the D16A6 pistons and use a Z6 head and gasket- you'll get a 8.5:1 compression ratio. Even with the smaller chamber Y8 head and 2 layer Y8 gasket, you'll still only be up at 9.02:1 compression. The PM6 pistons are dished and shorter compared to D15B non-VTEC pistons. You'll lose compression if you swap them into a D15.
     
  16. brian11to1

    brian11to1 Senior Member

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    Most importantly the question in my head... is there enough valve clearance to ut an 16 valve head on a 8 valve piston equipped engine? As Mike stated, make sure you have clearance between the Valves and Pistons, as the HF pistons most likely do not have 4 valve releifs.
     
  17. ryan89crx

    ryan89crx Senior Member

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    my hf motor only had 2 valve reliefs per piston, so the vtec head will have interference with teh valves. dont want to knock holes in the top of the pistons do you?

    and the zc came in 3 different forms:
    sohc non-vtec zc = same as the a6
    sohc vtec zc = same as the z6
    dohc zc
     
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