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    Rebuild break in?

    Experienced engine builders, what's your advice on post rebuild engine break in? Process, oil weight etc.

    Thanks
    "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

    1987 E30 3L Turbo Stroker Das Beast
    2002 E39 M5

    #2
    There were some good threads about this in the past.. I can't remember if they're here or were on E30tech (which has been dead for years now).

    You probably won't get a consensus. But, I will say, I drove mine hard from day 0 - and 100,000 miles later it's still going strong. no smoke or oil burning. leaks, well, you can't really avoid that with an M20..
    Build thread

    Bimmerlabs

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      #3
      I just broke in a motor, and I used this as a guideline: http://www.mototuneusa.com/break_in_secrets.htm

      Basically, over the course of maybe 50 miles, I did a series of pulls, and gradually increased the amount of throttle, and the point in the rev range that I'd stop at, until I was going full throttle to redline, and engine braking back to slow down between pulls.

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        #4
        My favorite advice, from Digger: "Drive it like you stole it and avoid steady speeds and revving it out all the way for first few hundreds of miles"
        "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

        1987 E30 3L Turbo Stroker Das Beast
        2002 E39 M5

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          #5
          i would get it running upto to temp first time make sure it runs properly, has oi pressure, gets hot, no leaks, AFR not overly rich, bleed coolant, run it above idle rpm during that time to ensure theres plenbty oil being flung around then let it cool down, adjust lash and retorque head bolts if ARP. then warm it up and break it in lots of throttle input verying rpm and load alot

          dont keep oil in there for more than a 30mins or so before changing it and filter to remove all the trash that got in during assembly

          i'd probably use a dedicated breakin oil but i have used normal mineral oil but make sure its not the best stuff as the oil is the final honing oil and thus should not be so good it doesnt allow some amount of friction. oil should have extreme pressure additives like ZDDP, low TBN, low calcium, low moly, low detergent.
          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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            #6
            Yeah, what they ^^ said!

            No synthetics, get it warm, then get out there and get cylinder pressure on it.
            So pretty hard 2nd and 3rd gear pulls, followed
            by coast- downs in 3rd to pull high cylinder vacuums.

            I have found that the first run's critical, too- the rings really need that first
            20 minutes to be high pressure. The cam needs lots of lube, too, so don't let it idle
            below 2000. And DO run a high ZDDP break in oil, followed by a high ZDDP oil
            for the first few thousand miles at least.

            Been doing it that way for the last 20 years, and it always works out pretty well.

            t
            now, sometimes I just mess with people. It's more entertaining that way. george graves

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              #7
              Well i had a question posed but just saw who started the thread lol removed question
              Last edited by turbski; 05-14-2021, 09:04 AM.

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                #8
                Motoman /\

                Try to time priming the oil pump close to start up, you can watch your gauges build oil pressure, I like to do with valve cover off to watch everything get a coat of oil.

                Rev 1000 - 3000 initial start while warming up

                Hard accel and decel, varying loads and gear working your way up the RPM band - 50 miles, Oil service - Brad Penn 30w break in oil.

                Same but less hard accel and decel varying loads with engine breaking till 500 miles, Oil service, Normal oil you plan to use.



                I was up above it, Now I'm down in it ~ Entropy - A Build thread.
                @Zakspeed_US

                Comment


                  #9
                  Btw meant that in the most respectful sense.
                  would it be ok to use an existing dyno tune on a fresh build, going from 2.5 to 2.7 if I re did the required fuel in megasquirt? Everything else is the same

                  Comment


                    #10
                    I made a stupid mistake while break in i swap a used fuel pressure regulator (without testing it) before break in and it was running super Rich during break in (50 mile) one intake valve got stuck due to heavy deposits although car weren't black smoking i didn't know till i heard the piston the hitting the valve on the way up to close the intake valve, Got the head off and all cylinders were covered in black and the piston with the stuck valve has oil in it.
                    Head rebuild is what i am doing now.

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