compression

Discussion in 'Engine Topic' started by 79Cam->, Nov 7, 2006.

  1. 79Cam->

    79Cam-> Veteran Member

    Messages:
    240
    Likes Received:
    0
    Joined:
    Jan 16, 2006
    Location:
    Minnesota,Richfield
    im rebuilding my engine and trying to deside what compression to build it to theres two kits im looking at one with 9.5:1 compression and another with 12.5:1 compression if i do the high compression id have to run a 100 Plus oct right? but the lower could run plain 92 right? ive been thinking of maybe converting it to E85 cuz that would burn in it right what you all think
     
  2. nogoty

    nogoty Veteran Member

    Messages:
    147
    Likes Received:
    0
    Joined:
    May 10, 2006
    12.5 to 1 is not going to be to enjoyable if you plan on driving in the streets alot
     
  3. rustbucket79

    rustbucket79 Veteran Member

    Messages:
    9,076
    Likes Received:
    2
    Joined:
    May 29, 2003
    Location:
    British Columbia, Canada
    Regardless of what your buddy next door or anyone else says what they think will work, high compression belongs on the track, not the street. If you build an efficient 9.5:1 engine you have a car that can buy gasoline wherever you go, and it won't cost you an arm and a leg to refuel. It should run happily on regular during the cooler part of the season and those times you want to beat on it or the ambient temperature is high put in some 92 and you're good for anything.
     
  4. Marks71BB

    Marks71BB Veteran Member Lifetime Gold Member

    Messages:
    11,834
    Likes Received:
    5
    Joined:
    Aug 25, 2002
    Location:
    Gods country in the beautiful Sierra Mountains of
    You have two extremes there 79Cam get somewhere in the middle with 10.25:1 or so and keep it tuned. best of both worlds. ya can run pump gas (depending on the cam) and get the most out of your engine.
     
  5. pdq67

    pdq67 BANNED

    Messages:
    10,496
    Likes Received:
    1
    Joined:
    Jul 26, 2001
    Location:
    Columbia, MO, USA
    I figure that E85 is good up to 13.5 to 1 CR. IF you can buy it ALL the time locally??

    pdq67
     
  6. hhott71

    hhott71 R.I.P 11/19/18 Lifetime Gold Member

    Messages:
    14,377
    Likes Received:
    8
    Joined:
    Mar 30, 2001
    Location:
    Joplin Mo. 64801
    the CAM dictates the compression.
    Match the components and succeed.
     
  7. Travisty

    Travisty Veteran Member

    Messages:
    659
    Likes Received:
    0
    Joined:
    Mar 6, 2000
    Location:
    Omaha, NE USA
    Don't forget that E85 has a lot of the same corrosive characteristics as methanol though.
     
  8. jaykay-uk

    jaykay-uk Veteran Member

    Messages:
    400
    Likes Received:
    0
    Joined:
    Jun 15, 2006
    Location:
    milton keynes.uk
    jk

    what i'm try to figure out is the differant between us gas and uk gas.
    your 87= uk 92oct.
     
  9. lluciano77

    lluciano77 Guest

    The way you gave the compression numbers above, it sounds like you arre going by the piston manufacturer's specs. You can't go by that. You have to do the math using the actual figures of your engine.
     
  10. 74RAT

    74RAT Veteran Member

    Messages:
    3,401
    Likes Received:
    3
    Joined:
    Dec 28, 2003
    Location:
    ft. stockton,tx,usa
    our pump octane ratings are based on: research octane + motor octane divided by 2 = pump octane. the 2 are averaged for the pump number here.

    not sure how they get your numbers over there. this article might help.

    http://www.prime-mover.org/Engines/GArticles/octane.html

    see if this gets you anywhere with how the numbers are derived in your country. hope it helps.
     

Share This Page