10:1 CR 383 and 93 pump gas?

Discussion in 'Engine Topic' started by boogie, Nov 27, 2012.

  1. boogie

    boogie Veteran Member

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    Wanted to see if some of you guys are succesfully running a 10.1:1 CR on 93 pump fuel. Here are the details:

    383 SBC with 6" rods, Probe 12.8cc dish pistons, "906" Vortec heads that cc just under 63. Pistons are .020 below deck and using a .028 GMPP gasket.

    The cam is a bullet HR 278/286 on a 108 lsa

    DCR computes to 8.13 if you look at that.


    Tell me some good stories
     
  2. twozs

    twozs Veteran Member

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    my ls1 2001 camaro has 10.1 to 1 from the factory and it runs fine on 93 (actually so does my nissan 3.5 altima)
     
  3. hhott71

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

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    11:1 compression using 93 octane and it works just fine.

    10:1 is a piece of cake/



    91 octane may work too.
     
  4. boogie

    boogie Veteran Member

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    Its a carbed motor BTW.
     
  5. cmonson

    cmonson Veteran Member Gold Member

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    10.5:1 on 93 here. No issues.

    Cam selection is everything...
     
  6. boogie

    boogie Veteran Member

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    Mind posting some engine details? Iron heads? Cam specs?
     
  7. Damon

    Damon Veteran Member

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    It should be OK. Check your cranking compression. If it's north of 200 PSI you may have issues if you "lug" the engine below ~3000 under significant load. Cranking compressions of 210, 220, 230 PSI or higher is where carb'ed Gen1 small blocks have issues on pump gas on the street (especially after they get some miles on them and carbon builds up in the chambers and piston faces). Otherwise, it seems in the realm of sanity to me. I think you'll be fine.
     
  8. hhott71

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

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    The 11:1 motor uses a 650 dp, see sig.
     
  9. deathmunchy

    deathmunchy Member

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    Whats the highest Compression ratio you want to use on pump gas? I was reading somewhere static isn't so much relevant here as dynamic and that a 9.5:1 Dynamic is where you start getting into 93+ territory. Is that right?
     
  10. Todd80Z28

    Todd80Z28 Moderator Staff Member Lifetime Gold Member

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    It's more like 8.0:1 actually. A 10:1 engine with a 215° @ .050" cam is going to be there.
     

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