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are 12 cr pistons streetable?

Discussion in 'Engine Building' started by word, Feb 2, 2004.

  1. word

    word Senior Member

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    hi,
    i'm pretty set on the wiseco 85 mm 12.8:1, 7 cc for a b18c block. i'll be running a stock b16a head for the time being. Would this setup cause pinging on 93 octane pump gas without hondata? i'm only running a vafc. would the 7cc dome clear the valves?

    What power gains would be reasonable if I were to bump up the compression another point to the 13s and would it still be streetable?

    thanks.
     
  2. B16

    B16 Super Moderator VIP

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    you'll need at least hondata and larger injectors, 370-440cc range. and a lot of tuning.
     
  3. MaliWho97

    MaliWho97 Senior Member

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    And a phat wallet to buy high octane fuel.
     
  4. 2fastaccord

    2fastaccord Senior Member

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    That is about the highest I have heard anyone running and still trying to stay streetable.
     
  5. word

    word Senior Member

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    i'm in georgia, all gas stations sell 93 octane gas :)



    12 or 13??
     
  6. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    I run 93 octane, and I've run 12.6:1 compression on a VAFC and 12.4:1 on Hondata. I was able to run a lot leaner and powerful on the 12.4 and Hondata (13:1 a/f ratio) than the 12.6 and the VAFC (11:1). It's streetable if you tune it right. I would recommend you stay with a fully programmable system like Hondata if you want a setup like that to run nicely every day.

    On the other hand, the 12.6:1 compression setup on the VAFC ran for 45k miles without any issues. I DID have to run pretty rich though.

    Next build- 12.77:1 compression on Hondata and 93 octane gas, daily driven. My builder says "no problem" on tuning that setup.
     
  7. B16

    B16 Super Moderator VIP

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    thats good to hear, i still freak out about this new motor i have with 12.3:1 on 91.
     
  8. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Well, that is on 93 octane... but I know that people out in Cali have run mid 12 compression on 91 too.
     
  9. shaneb

    shaneb Member

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    What would the cr be on a b16 head and itr bottem end w/ctr pistons.....

    I have bin running 1/2 ,100 octane and 1/2 91 octane in a 10 gal tank...

    It seems to run fine .....No hondata , just chiped ecu
     
  10. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Here- go find out for yourself.

    http://www.c-speedracing.com/howto/compcalc/compcalc.php

    I have no idea what you used for a head gasket or if you milled the head/block any, and if so how much... so here's a guess:

    12.1:1 compression

    If that's what you're really running (C5 bottom/top, B16B pistons and standard head gasket), then you'll be fine on 91 octane with a real tune. Go grab a Hondata and have some fun!
     
  11. shaneb

    shaneb Member

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    on the cr chart...What dose the piston to deck height mean?? should i put b16 or b18 on that option??

    BTW , my head is stock of a stock b16a , i got the itr bottem end sperate , and a oem 3 layer head gasket...
     
  12. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    The B16A head is the same as the B18C5. The C5 just has a slight port and polish job from the factory, that's all. Piston to deck height is the distance from the top of the piston to the deck of the block. You use the piston to deck height from the piston you're using, assuming that the compression height (center of wrist pin to top of piston, not including dome or dish) is normal. If you're using a custom piston or have shaved the deck, then you'll have to recalculate.
     
  13. shaneb

    shaneb Member

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    so what option should i put ? should i b16a piston to deck height or b18 ?
     
  14. handlebarsfsr

    handlebarsfsr Senior Member

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    your kinda defeating the point of extreme compression and displacment by running a completely stock head imo. you need some serious headwork to go with it or your just gonna choke the motor, especially at high rpm.
     
  15. JDMilan

    JDMilan Senior Member

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    like calesta said, he ran it and had no problems, but it doesn require tuning from application to application. I would stick wtih the 12:1 on the safe side, that way you get a little slack in their.
     
  16. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    B16B pistons, use B16B piston to deck height.
     
  17. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Yes and no- you have to start somewhere. Take care of everything needed inside the block, then do the cams and head stuff later. Of course, if you're going for a port/polish, then you'll have to pull the head again... but you can still take good advantage of high compression without screwing around in your ports.
     
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