Compression questions blown alky

Discussion in 'PSI Superchargers Tech Questions' started by BlownVolvo242, Feb 17, 2020.

  1. JGRacing

    JGRacing New Member

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    #21
  2. JGRacing

    JGRacing New Member

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    I am not sal , sorry wrong person , I race my own alcohol
    Dragster , just was stating my experience, I am out of this
    Good luck to all . JG .
     
    #22
  3. Critical Mass

    Critical Mass Member

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    Mr. Blown Volvo,
    It sounds to me that you really don't know the CR, your trusting the guy you bought it from? If I were you I would measure it; that would solve any disputes your getting from this site!
     
    #23
  4. BlownVolvo242

    BlownVolvo242 New Member

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    Static compression is 14:1. I don’t have the cam specs in front of me so you are correct I don’t know the dynamic compression. But overlap would lower it abit. What kind of dynamic compression are you guys seeing at what boost levels? I get the window of safe tuning is a lower dynamic compression that’s just like anything. But even at 10:1 compression if you made 40 lbs of boost your dynamic compression has got to be into the 30:1 range. Are you guys just having detonation issues at higher dynamic ratios? I’ll grab the cam card tomorrow
     
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  5. StingRay

    StingRay New Member

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    One thing also comes to mind when reading these post is, what is the altitude you are running at when you said "Rocky Mountain superchargers"? If only running at high altitude tracks you can run 1.5 to 2 ratios higher compression. No supporting information was given in posts.
     
    #25
  6. BlownVolvo242

    BlownVolvo242 New Member

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    right on! Yessir were over a mile high most days sometimes almost 2
     
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  7. Templar Motorsports

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    GregM784
    What is the reason people run a higher compression? What would be the advantage?
     
    #27
  8. swsc4133

    swsc4133 Member

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    A friend I have helped has right at 12 to1 in a dragster, 498 cu. in. Good 110 pump. Keep it happy and the plugs a little light and oh yea usually over 7500 of d.a. Runs very well for Albuquerque and the like.
     
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  9. J.M.J pegasus

    J.M.J pegasus New Member

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    Few years ago i ran 13.8to1 on solid headed 540 screw blown BBC with 30-32# boost, randy Anderson fuel system.but I ran at higher density altitudes(6500-9500' da) max timing 28* anymore and the rod bearings wouldnt mike out... it either ran like a champ or had a head gasket or 2 hanging out..tuning window was pretty narrow. I was changing main jets by singles..107 was fat..105 was kick in the pants.. 103 basket of parts and a long ride back home. My current setup I'm down to 10.7 to 1..increased overdrive/boost and added more timing,more fuel and everything is alot happier...
     
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  10. WIDEOPEN231

    WIDEOPEN231 Member

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    I started out with 13:1 and 14-71 blower. Cpl years later we went to 12:1. Ran faster and hurt less parts. WIth a NA motor compression is part of building power. Throw a blower on top and its just taking up room in combustion s chamber that can be filled with fresh air and fuel. Want more pressure just turn the pump up some.

    IMO cutting pistons or more head gasket is best bet. You can sink valves but that just wasting good seat in the heads. A set of pistons may rum a 1000 but kicking rods will be a lot more.

    Best bet if you are new drop compression back and ease it up as you go,More blower,more fuel and little more timing as you go. You save money and learn as you go.
     
    #30
    Templar Motorsports likes this.
  11. WIDEOPEN231

    WIDEOPEN231 Member

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    As for cam something along the lines of crane 286-500 is good safe bet. Old design but hell it works.
     
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