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Compression ratios

This is a discussion on Compression ratios within the Internal Engine forums, part of the LSx Technical Help Section category; Ya me too,,,sounds as though the octane reading is inflated out there,,,or not done in the same fasion as back ...

  1. #21
    Moderator Firebirdjones's Avatar
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    Ya me too,,,sounds as though the octane reading is inflated out there,,,or not done in the same fasion as back here in the states. Thats a real difference.

    The best pump octane is 94 back east and I ran 10.6:1 sbc motor with cast iron heads on it just fine. Had to have a sharp tune but I drove it daily without issues. My firebird with a real pontiac motor is 10:1 with cast iron heads and it only complained on hot days, but had a little gear and tight converter. Plus stock cast iron pontiac combustion chambers are not that efficient anyway, they are a little more finicky.

    I run old school V8's with aluminum heads at 11:1 no sweat at all on 91 octane out here now. We just dynoed my fathers 455 pontiac with aluminum heads and 10.5:1 compression on 87 octane and made 603 HP

    If we had a real 98 octane rating out here I would have been set. Any old timers here that remember Sunoco 260??? I think that was around 100 octane at best. I'm depressing myself now.

  2. #22
    cutting and welding mark21742's Avatar
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    Quote Originally Posted by Firebirdjones View Post
    Ya me too,,,sounds as though the octane reading is inflated out there,,,or not done in the same fasion as back here in the states. Thats a real difference.

    The best pump octane is 94 back east and I ran 10.6:1 sbc motor with cast iron heads on it just fine. Had to have a sharp tune but I drove it daily without issues. My firebird with a real pontiac motor is 10:1 with cast iron heads and it only complained on hot days, but had a little gear and tight converter. Plus stock cast iron pontiac combustion chambers are not that efficient anyway, they are a little more finicky.

    I run old school V8's with aluminum heads at 11:1 no sweat at all on 91 octane out here now. We just dynoed my fathers 455 pontiac with aluminum heads and 10.5:1 compression on 87 octane and made 603 HP

    If we had a real 98 octane rating out here I would have been set. Any old timers here that remember Sunoco 260??? I think that was around 100 octane at best. I'm depressing myself now.
    my friend Bill 100octane in his TA with 14:1compression so there is definately a quality difference between here and aussie

  3. #23
    Junior Member Bezerk's Avatar
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    Monaro Yellow
    1989 R32 Nissan Skyline

    that would be right, we recieve the rough end of the stick again lol.
    our v8 supercars run or claim to run pump fuel, but it looks a little different in colour to what you get at the gas station, but they claim to be making 700hp out of a 350ci small block. they have unlimited tuning technology and funding, and the engines expire rather quickly but it is still a good effort. they are all EFI also. be interesting to get some of those engine specs but fat chance.

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