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Octane And Cr?

Discussion in 'Engine Building' started by honda_mach3, May 1, 2003.

  1. honda_mach3

    honda_mach3 Senior Member

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    I'm running a setup of a B16A2 head on B18C block with JE 12.5:1 CR. If i put the B16A2 head on, will it lower my CR? or raise it? with such a high CR, will a 93 octane gas be able to power it?
     
  2. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    93 octane is fine on 12.5:1 compression with decent tuning. I did it on 12.6:1.

    If your pistons are rated at 12.5:1 for a B18C1 engine, then you'll have slightly lower compression with the B16A2 head on your block.
     
  3. CriztheWiz

    CriztheWiz Banned

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    It should drop down to about 12.25 to 1
     
  4. lazy bum shaughn

    lazy bum shaughn Junior Member

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    What kind of fuel management are you using?

    There are people running 13:1 compression with Hondata tuning..
     
  5. pills_PMD

    pills_PMD Super Moderator

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    i will run 12.3:1 on 93 octane with no problems once its tuned, with hondata of course
     
  6. 2 litre EG

    2 litre EG Senior Member

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    personally im running with 11.8:1 on 91pump gas here in cali... i plan on bumping up the compression once i can afford to pick up a GSR swap from my buddy and rebuild a whole new motor... i just need to come with 1500 to pick up my new motor ;]

    i cant stand shifting at 8800... must go higher :evil laugh:

    :p B)
     
  7. JDMilan

    JDMilan Senior Member

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    Just my .02cents, 12.0 would be the limit for me with no tuning on 93, with tuning just like the guys said you can go up to 13.0 maybe a little more but it MUST be tuned.........


    and that doesn't mean the butt dyno :p

    Milan
     
  8. mical0259

    mical0259 Junior Member

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    how do you run such high CR? i just did a swap with 12.2:1 in my sohc vtec and it was knocking bad at 1300 rpm. it had a chipped ecu that ran rich and thats it. adjusting the ignition timing made no difference.
     
  9. honda_mach3

    honda_mach3 Senior Member

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    well i've been running on it now for a couple of weeks now. no problem. first off, i adjusted the rod angle to 13 degrees so i won't throw too much pressure on the main bearings. second, i have dyno tested it for many many times, running it on the dyno for many hours just to get the right tune. every little thing can effect the drivability of it. ignition plays a good role. the pistons are heat resisted carbon coated to avoid preignition, and did my best to avoid detonation. with hard effort and good brains, tweakin your car to get the best performance is not so easy. and BIG BUCKS plays something huge.
     
  10. lsvtec

    lsvtec GNU/Linux Evangelist

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    I am wondering how you accomplished this and why you think it has any affect on the pressure put on the main bearings?
     
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