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    Optimal Compression Ratio for full mod Polaris 600 HO?

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    • Member since
      August 2013
    Optimal Compression Ratio for full mod Polaris 600 HO?
    Posted by ModOutlawKart on Sunday, October 19, 2014 11:22 AM

    I know it kind of a loaded question, but I am trying to save a little $$$ on the dyno time. Where have you guys found the best power on the Polaris HO in full race trim. (open mod) 16.8/1 or even more like 17.4/1?

    I am tuning for short throttle busts.

    The current fuel I am running is Sunoco SR18.

    Holeshots are a very important factor as well as off corner responce.

    I want to know at what point will compression become counter productive?

    Currently I am running 17.4/1 18.4 cc corrected. reads about 180 cranking compression on my snap-on gauge. I race tight short oval Ice.

    Thanks for any input in advance.

    • Member since
      August 2013
    Posted by ModOutlawKart on Sunday, October 19, 2014 12:03 PM

    Few other things that maybe inportant, Pipes are tuned to 8800 rpm and I want to run the squish at .050.

    • Member since
      May 2006
    • From: lac-st-jean,quebec province
    Posted by scramblered on Wednesday, December 3, 2014 12:38 PM

    betwwen .045 and .055 squish is where you need to be at,it sound a little high on compression ratio (and low on PSI),it become harder to hit proper RIGHT rpm with higher CR,i guess you should hold it at around 16.5 with c-14 fuel,timing retarded 1 degrees,more energy for each cycle that way or closer.



    -00 hot seat race mods/ flannery ports XCR 800 VES

    • Member since
      August 2013
    Posted by ModOutlawKart on Wednesday, December 3, 2014 7:34 PM
    Thanks Scramblered, I have been out to test and I will agree I lost about 250 RPM but I did gain big on the bottom and mid. For the very short bursts I am doing the higher compression seems to be quicker. But I think you are spot on with your advise. Also on the compression thing you are probably correct as well my compression gauge does not screw in you just hold it over the hole. I think a thread n one would probably read closer to 200 or so. I am right on the limit with Sunoco SR18.

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