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Turbo 325

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    Good tires then, maybe you have worse traction than I do because of gearing. I do have a 3.25 rear end and though I break traction in second with any reasonable amount of boost and third gear at 20psi of boost, the car doesn't deviate much. If you're smoking tires and deviating now an extra 100whp will have you shopping for drag radials. Are you keeping the 3071R for the 2.9 build? I'd be interested to see if you can actually get 450whp out of that turbo even with the bigger turbine housing. The compressor would be maxed out for sure.
    Last edited by varg; 05-14-2023, 06:35 AM.

    IG @turbovarg
    '91 318is, M20 turbo
    [CoTM: 4-18]
    '94 525iT slicktop, 600WHP or bust, forged M50B30 + S366SX-E project - updated 6-25


      Yeh it runs a 3.73, one of the next things I think I will be looking at after the engine build as its likely part of the equation of getting it to build boost better. Bit more load would be good.

      Keeping the 3071, being a GTX they out flow a non-gtx 3076 which is what I wanted initially but has better response. Seen some numbers made on other 2.5s (not M20s) of making 450-480rw with the gtx but we will see. Might have to be on E85 to get that yet.
      I would rather have a better curve thats a handful than just have all this peak power Il never use on the street. As it is I've never taken it past 120kmhr (75mph), these days I just like to open up the tap a couple of gears and I'm happy.
      Boris - 89 E30 325i
      84- E30 323i



        Getting closer to having everything I need to start this engine build, just waiting for HG, Springs and a Belt

        Details Below

        M20 Turbo Stroker
        8.5:1 Comp
        85mm Bore
        Athena Cut-ring Headgasket
        84mm stroke small counterweight 2242898 2.8L crank
        Molnar 135mm Power adder H-beam rods
        Supertech 1mm oversize valves with Inconel exhaust
        Schrick 272/272 Cam
        JE Custom Pistons with tuff coated skirts, deeper valve pockets, accumulator grooves & contact reduction grooves
        KM Steel Rocker arms
        Schrick Sport dual valve springs
        VAC Rocker Locks
        Gates Racing timing belt
        ACL Race series bearings
        Arp Studs

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        Last edited by bangn; 06-10-2023, 09:19 PM.
        Boris - 89 E30 325i
        84- E30 323i



          Rods - difference between standard and the power adder rods is the wall thickness on either side of the scallop, adds a little bit more weight but its still lighter than the OEM M20 rods coming in at 539g instead of 638g

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          Very hard thing to find these days
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          Last edited by bangn; 06-10-2023, 09:25 PM.
          Boris - 89 E30 325i
          84- E30 323i


            So head gasket arrived on a rocket ship, expecting rocker arms and intermediate shaft bearings to arrive in the next day or two. Then should be able to drop the bottom end off to the machinist.

            Athena 2mm Cutring gasket, the rings are smooth for block side and have three cutting grooves for the head. Hopefully have some success with this as feel like a bit of a Guinee pig

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            Boris - 89 E30 325i
            84- E30 323i


              Look at all these shiny parts. excuse my ignorance what is that red VAC thing? stops the rockers from moving side to side?


                Yep, Vac Rocker locks. Basically just giving the rocker stability and stopping the chance of it slipping off.

                So the steel rockers arrived, I put a rocker shaft in it and ran a 6mm stem through the adjuster hole onto both rockers to gauge how different they were in terms of rocker ratio/lift changes
                Basically what I found is the centre of the pad is the same height and position as oem. KM Pad is a bit wider and a bit longer. I'm still going to measure them up in the head
                so ive got some real data but I think any difference if any will be comparable to wear. At this point it seems the pad arc is comparable to OEM. Here's hoping the steel clamps the eccentric adjuster
                with enough side load they don't move.

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                Boris - 89 E30 325i
                84- E30 323i


                  I like the bigger pad design. Hoping of course that the geometry is right.

                  Did KM Cams give any recommendations about spring rates for these? Obviously valve train inertia is somewhat higher than with aluminium rockers.


                    I picked them up from bimmerheads but they said the schrick dual springs are the go
                    Boris - 89 E30 325i
                    84- E30 323i