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Compression ratio 98 octane

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Compression ratio 98 octane

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    Compression ratio 98 octane

    Hi pplz, im from Australia and we have 98 octane gas here on pump so i want to take advantage of this and try to rasie my compression ratio and by the way i drive a stock LS. i just want to know how much compression can i run on 98 octane safely. Secondly other than using higher octane gas are there any negative side effects of a higher compression. eg raliability? also if i get p30 pistion can i just put them on and not have to worry about ecu, timing or anytyhing else?

    #2
    if you bump the compression you really should do something along the lines of getting it tuned...

    w/ 98 octane you could run 12.5:1 all day long.

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      #3
      I run 12.25:1 on ~94 octane OK.

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        #4
        what does 98 octane cost?

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          #5
          you could do 13:1 on good tuning.
          don't undercam your motor.

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            #6
            waaaa the highest we have here is 91 octane, unless you get ethanol blended 92 but ive heard that its not as good, im now jealous.

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              #7
              Originally posted by tegdablunt
              what does 98 octane cost?
              5 gallons of 103 costs $33.
              Mix it with 4 gallons of 91 octane (about $2.30 locally) and you'll have 9 gallons of 98 octane.

              (33+(4*2.30))/9 = $4.68/gallon

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                #8
                Originally posted by tegdablunt
                what does 98 octane cost?
                Well over here it cost 8 cents extra per litre then normal only and our current exchange rate about 6 cent for u over there extra and 91 is just normal here.

                Sorry im noob and over here modifying isn't all that big and we might not have the services you have over there. What is actually involved in tuning? and can i do it my self?

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                  #9
                  Holy cow, build a beast!!!!!!

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                    #10
                    tuning basically means finding a tool that can tweak the amount of fuel at various rpm's, and then hooking a car up to a dyno, that has a air/fuel metre.

                    you then add or remove fuel at various rpm's to make the most power possible, while monitoring your air/fuel ratio to make sure you don't remove too much fuel.

                    fuel tuning is the main part, then there's also timing adjustments which can be done with cam gears, or using aftermarket tuning devices like hondata or greddy e-manage

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                      #11
                      Originally posted by arw321
                      you could do 13:1 on good tuning.
                      don't undercam your motor.
                      what kind of redline would those cams have to have? once you start running those CR in an LS, and cams to match. you gotta have probably something like a 9000rpm redline, i don't know if it's worth it to try that in an LS, the mopney would be retarded.

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                        #12
                        Could i get away with not tuning the car at 13:1 cr if i can't can i aim for a lower number and not tune it? to tell u the truth, i was just going to rebuild the motor by just changing some gaskets rings etc but it would seen like a waste if i didn't do more since the gaskets and rings here cost like $650 US for OEM and only a bit cheaper aftermarket. and i don't want to go too extreme..

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                          #13
                          BTW .... RON 98 octane in Australia is not the same as gas here...

                          The US/Canada uses a different Octane rating system at the
                          gas pumps than most other countries.

                          They use the U.S. Cost of Living Council (CLC) index
                          which is the average of the Research Octane Number (RON) and
                          the Motor Octane Number (MON):


                          CLC = (RON + MON) / 2

                          RON = Research Octane number (ROZ in Germany)
                          MON = Motor Octane Number
                          CLC = U.S. Cost of Living Council

                          This translates to (roughly):

                          91 RON = 87 CLC (Regular)
                          95 RON = 91 CLC (Premium)

                          Comment


                            #14
                            Originally posted by Blk_92_GSR
                            BTW .... RON 98 octane in Australia is not the same as gas here...

                            The US/Canada uses a different Octane rating system at the
                            gas pumps than most other countries.

                            They use the U.S. Cost of Living Council (CLC) index
                            which is the average of the Research Octane Number (RON) and
                            the Motor Octane Number (MON):


                            CLC = (RON + MON) / 2

                            RON = Research Octane number (ROZ in Germany)
                            MON = Motor Octane Number
                            CLC = U.S. Cost of Living Council

                            This translates to (roughly):

                            91 RON = 87 CLC (Regular)
                            95 RON = 91 CLC (Premium)
                            great info!

                            Comment


                              #15
                              Originally posted by Blk_92_GSR
                              BTW .... RON 98 octane in Australia is not the same as gas here...

                              The US/Canada uses a different Octane rating system at the
                              gas pumps than most other countries.

                              They use the U.S. Cost of Living Council (CLC) index
                              which is the average of the Research Octane Number (RON) and
                              the Motor Octane Number (MON):


                              CLC = (RON + MON) / 2

                              RON = Research Octane number (ROZ in Germany)
                              MON = Motor Octane Number
                              CLC = U.S. Cost of Living Council

                              This translates to (roughly):

                              91 RON = 87 CLC (Regular)
                              95 RON = 91 CLC (Premium)

                              wow, finally someone else gives the octane lecture before i have a chance to. :p


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                                #16
                                I can get true 94 here in Cleveland at the pumps.

                                There's also a place around the corner from me that sells race gas. I've never priced it though, because I've never had to.

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                                  #17
                                  So can i just chuck on the pistons to raise my CR and hope for better performance or should i just forget it if im not gonna tune it. or can't i do that?

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                                    #18
                                    get PCT pistons instead, they'll raise your compression more

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