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Mazda bottom end upgrades.

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    #1

    Mazda bottom end upgrades.

    I am thinking of getting my Mazda MA (from a 626 2.0L) rebuilt as it has had water in the bores and is now pitted.

    But, i am undecided as to what i want to get done in the rebuild. I have been quoted a very reasonable price to get the the rods and crank balanced, and i'm pretty sold on getting this done.

    Apparently, the weak point with these motors are the rod bolts breaking under extended high rev sessions. What can i do about this? Can i simply buy stronger items? (eg ARP bolts) Do the rods themselves need strengthening/replacing? I am planning to run a 40/80 cam in it, and thus have it safely revving to 7,000-7500rpm.

    Getting a set of oversize pistons and rings is no problem, i am just unsure of what else i should be getting done. I dont imagine i need to get the rods shotpeened for strength - as really, even at it's highest state of tune, this engine will still make little power.

    Ultimately, i would be aiming to get a low 16sec quarter out of the motor (in a capella weighing 1tonne). I think 15's would be out of reach, however.

    What things do i need to take into consideration to achieve this?
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    #2
    yeah ARP bolts is a good idea, or brand new ones from mazda. Again, IMHO most "rod failures" are caused from the rod nut coming loose, either from the bolt stretching or from vibration. Particuarly on a n/a motor.

    either ARP bolts or new ones from mazda. Personally I loctite the nuts in place with loctite 232 or equivalent, but there is heated debate about doing this so make your own decision on that one.
    Turns out, far too much has been written about great men and not nearly enough about morons


    Originally posted by seedyrom
    my neighbours called the cops...... not because of the sound of me working in the garage was too loud, but because i taped a cardboard box to my back, covered my self in vaseline and pretended i was a snail on their lawn

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      #3
      I was discussing my proposed engine build with some people today, and they mentioned instead of getting over-size pistions that i get the current ones "blown out."

      I didn't quite grasp the concept he was describing, but he mentioned shot peening the inside of the pistion to make it expand to take up the size of the over bore?

      What's all this about then ?

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        #4
        you could get more compression by putting a big dob of araldite on the piston crown too

        IMHO it's in the category of "It May Well Work Just Fine But I'll Sure As Shit Never Do It" :p
        Turns out, far too much has been written about great men and not nearly enough about morons


        Originally posted by seedyrom
        my neighbours called the cops...... not because of the sound of me working in the garage was too loud, but because i taped a cardboard box to my back, covered my self in vaseline and pretended i was a snail on their lawn

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          #5
          Duly noted

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            #6
            it's fine for just a re-ring where the piston skirts need to be belled out a few thou, but you wouldnt do it on a fresh bore.
            Turns out, far too much has been written about great men and not nearly enough about morons


            Originally posted by seedyrom
            my neighbours called the cops...... not because of the sound of me working in the garage was too loud, but because i taped a cardboard box to my back, covered my self in vaseline and pretended i was a snail on their lawn

            Comment

              #7
              Hey Secoh,

              Which gives the highest compression ratio, superstrength Araldite, or the five minute stuff ?
              Tony

              Comment

                #8
                mate, you cant go past the 5 minute stuff!! Best Bang for your Buck mate! (or is that biggest bang? :D)
                Turns out, far too much has been written about great men and not nearly enough about morons


                Originally posted by seedyrom
                my neighbours called the cops...... not because of the sound of me working in the garage was too loud, but because i taped a cardboard box to my back, covered my self in vaseline and pretended i was a snail on their lawn

                Comment

                  #9
                  Ha ha ha he he, good one Secoh !
                  Tony

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