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Knife-Edge or Crank Scraper?

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    Knife-Edge or Crank Scraper?

    Do I knife-edge the whole crank, or just knife-edge the leading edge and use a crank scraper?

    Yes yes, I could knife-edge the whole crank and use a crank scraper... but then I'd have to make one up... which I don't really wanna do, but I could.

    I found a company that makes crank scrapers. Ishihara-Johnson crank scrapers and I've been talking to the guy that works there and they're currently working on a crank scraper that works with the MSBP... but only for a stock crank.




    JoN - Automotive Machinist Journeyman/Refrigeration Mechanic Journeyman
    Member of MX-3.com
    1996 Mazda MX-3 RS - Creek Blue Mica
    1993 Mazda MX-3 GS SE - Raspberry... RIP


    Racing BP (Project "Blue" Marlin)... Twin Scroll GT3071R, breaking 30psi at the moment!

    "Do it ONCE, do it RIGHT!"

    #2
    what exactly is the supposed benift of a crank scraper?
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    1992- project FE3..... 313 WHP @ 9.3psi




    I pet my dash when I get into the car..."good car"
    he actually has a mazda tree, parts grow on it

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      #3
      wouldn't a crank scraper reduce the life blood of oil getting to the rods/pistons?
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      1992- project FE3..... 313 WHP @ 9.3psi




      I pet my dash when I get into the car..."good car"
      he actually has a mazda tree, parts grow on it

      Comment


        #4
        From my research a crank scraper wipes the oil off the crank... mainly the counter weights. This reduces the reciprocating mass on the crank letting it spin more freely. That's the main benefit, others are:
        · Less rotating mass for the engine to accelerate because of the removed oil
        · Less loss of power because of excessive drag caused by the windage cloud
        · Helps reduce engine damaging oil-foaming
        · Helps avoid oil starvation by keeping the oil in the pan during hard braking and turning as well as during off-road driving
        · Helps to cool critical engine parts by quickly returning heated oil to the sump
        · Helps to prevent the cylinder walls from being overloaded with oil
        · Can help with fuel efficiency

        JoN - Automotive Machinist Journeyman/Refrigeration Mechanic Journeyman
        Member of MX-3.com
        1996 Mazda MX-3 RS - Creek Blue Mica
        1993 Mazda MX-3 GS SE - Raspberry... RIP


        Racing BP (Project "Blue" Marlin)... Twin Scroll GT3071R, breaking 30psi at the moment!

        "Do it ONCE, do it RIGHT!"

        Comment


          #5
          is a crank scraper the same as a windage tray? i've seen large-scale use of these in domestics as well as hondas

          Comment


            #6
            Originally posted by bpt323
            wouldn't a crank scraper reduce the life blood of oil getting to the rods/pistons?
            To answer your question, no. The pistons are oiled through the oil squirters that cool the piston, and the rods are oiled through the oil holes and passages in the crank and then to the rod bearings.

            JoN - Automotive Machinist Journeyman/Refrigeration Mechanic Journeyman
            Member of MX-3.com
            1996 Mazda MX-3 RS - Creek Blue Mica
            1993 Mazda MX-3 GS SE - Raspberry... RIP


            Racing BP (Project "Blue" Marlin)... Twin Scroll GT3071R, breaking 30psi at the moment!

            "Do it ONCE, do it RIGHT!"

            Comment


              #7
              Originally posted by esmacmil
              is a crank scraper the same as a windage tray? i've seen large-scale use of these in domestics as well as hondas
              "No, a windage tray serves a different but related basic function. It is present to act as a physical barrier between the rotating assembly and the sump reservoir. A crank scraper actively removes excess oil and returns it to the sump. Some windage trays do have scraper technology built into them but even then a scraper will approach the moving parts much more closely." - qutoed off Ishihara-Johnson

              A windage tray is kinda like our MBSP.

              JoN - Automotive Machinist Journeyman/Refrigeration Mechanic Journeyman
              Member of MX-3.com
              1996 Mazda MX-3 RS - Creek Blue Mica
              1993 Mazda MX-3 GS SE - Raspberry... RIP


              Racing BP (Project "Blue" Marlin)... Twin Scroll GT3071R, breaking 30psi at the moment!

              "Do it ONCE, do it RIGHT!"

              Comment


                #8
                good info, thanks

                btw...whats the acronym MBSP mean?

                Comment


                  #9
                  Originally posted by esmacmil
                  good info, thanks

                  btw...whats the acronym MBSP mean?
                  Main Bearing Support Plate
                  If you can't differentiate between brake and break, you should go back to school
                  -----
                  Miscellaneous Pics of Turbo Protege Build
                  Big Front Brake Install using Wilwood Calipers
                  Factory Service Manuals and Familia Brochures - PDF

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                    #10
                    thank you

                    Comment


                      #11
                      I guess no one knows which one is the better, since most don't know about the crank scraper.

                      JoN - Automotive Machinist Journeyman/Refrigeration Mechanic Journeyman
                      Member of MX-3.com
                      1996 Mazda MX-3 RS - Creek Blue Mica
                      1993 Mazda MX-3 GS SE - Raspberry... RIP


                      Racing BP (Project "Blue" Marlin)... Twin Scroll GT3071R, breaking 30psi at the moment!

                      "Do it ONCE, do it RIGHT!"

                      Comment


                        #12
                        seems skeptical as hell to me
                        ---Has ClubProtege helped you in someway? show your support by Contributing--- Click Here---

                        1992- project FE3..... 313 WHP @ 9.3psi




                        I pet my dash when I get into the car..."good car"
                        he actually has a mazda tree, parts grow on it

                        Comment


                          #13
                          crank scrapers are always a good thing but not really needed on most motors unless you are pulling alot of rev's in a bp id guess one would be a good idea to have at 9k plus.
                          mods: engine: fm stroker lightened and knifedged crank, 11:1, custom crank scraper, fully p&p head and intake mani, bored throttle body, flowed and matched stock injectors, rx7 vaf, apexi safc, gude race cams, modded ecu 8200 fuel cutoff, blaster coil, clutchmasters stage 3 clutch, fidanza fly wheel and timeing gears, msp diff, custom shortram in a cold air box

                          suspension: s/r struts intrack springs and intrax sway bars 15x6.5 rims kumho mx tires 205 50 r 15

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                            #14
                            crankscraper would be a whole lot less expensive then knife edging the crank. i've never knife edged a crank so I don't know if it's worth it or not, but i did have a crank scraper on my 383 LT1, butt dyno didn't show anything different, but if felt like it revved a lil easier.

                            93' 5spd DX
                            R.I.P

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                              #15
                              Unless you're trying to win some sort of competition, I'd buy the crank scrapper assuming its not rediculously expensive. Knife edging is REALLY high end and has VERY little benefit to anything but all out race engines. It's pretty much the LAST thing I'd do if I absolutely positively had to make the motor all out. Even the crank scrapper is pretty dubious on our motors, but if its not ungodly expensive you could try it out. Out of curiousity what all is done/being done to the motor in question?
                              -Mike
                              06 Taurus SEL/92 Escort GT/93 RX7 R1

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