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2.8L M20 9.8:1 stroker build: my 323i reincarnated

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  • betz
    Car had a "blown head", didn't care since I already had a "e" block in the works for a 2.7 stroker for my 323i.

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  • 2mAn
    Took you long enough to post pics! hahah

    Where is the rear trim? lemme have it

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  • betz

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  • betz
    started a topic 2.8L M20 9.8:1 stroker build: my 323i reincarnated

    2.8L M20 9.8:1 stroker build: my 323i reincarnated

    So the story goes.. I crashed my beloved 323i in a sharper than I thought downhill turn that caused unexpected oversteer. It was 1000% my fault with my shit driving ability is the reason I mangled one of the last 323i's to exist in California.

    After dumping about $1k into straightening the body it became clear that the 323i wouldn't be completely straight without spending inordinate amounts of money.

    So I started searching for an early model shell. I saw an ad on craigslist for a pretty shitty looking 325e, but it was super close so I basically said fuck it.

    Owner was a skater dude who wanted to drift it but lost interest after he got an E36.

    He offered I take it for $200 so he'd have money to go to the beach with his friends...

    So hell yeah I bought it

    Edit: I found a crisp $20 bill while cleaning the carpet, so it really was an $180 car.


    Alright, so I'm gonna try and help people who want to do this build by listing the parts required to make it happen. I will update it as I think of stuff.

    Main Engine parts:
    -Any M20 block
    -885 (325i) head. At least a 272 cam.
    -84mm Crankshaft from a 2.8 M50/52engine. E36 328i, E39 528i, etc.
    -Stock 325i short skirt pistons. These pistons have the domed top and the flat skirts.
    -130mm rods. Either from 325e, 320i, 323i etc
    -325i intake manifold, throttle body, AFM, airbox, boot, and ICV

    -This spacer (Just ask a local machine shop)
    -My block was decked exactly 0.020" or .508 mm for a CR of exactly 9.81:1 assuming a stock M20B25 is exactly 8.8:1
    -Shave off the non-structural looking part of the piston skirt.
    -Turn the crankshaft counterweights down pretty much all the way, right before you start hitting the other side of the crankshaft (the part that sticks out next to the connecting rod bearings)
    -Get the entire assembly professionally balanced: pistons, rods, crankshaft, flywheel, vibration damper, fan pulley, and pressure plate

    Electrical: (starting from 325e)
    -325i complete engine wiring harness
    -325i injector harness
    -Toothed crank wheel
    -CPS and CPS bracket
    -Motronic 1.3 ECU (173)
    -Recommend megasquirt or custom/dyno chip
    -Recommend Wideband (Innovate LC-2)
    -325i Spark plug wires (for CID sensor)
    -NGK BPR6ES spark plugs

    -At least 19 lb injectors.
    -325i 3.0 bar Fuel pressure regulator
    -Stock pump should be fine.

    -Stock cooling is fine. Either late or early model.

    March 2019 cotm


    In car

    From stop

    "Swing it bro!"
    Last edited by betz; 06-27-2020, 09:44 PM.