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Questions about tuning for a reliable 3 psi turbo build.

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  • Questions about tuning for a reliable 3 psi turbo build.

    Hey guys,

    So I've had my 89 M3 for close to 4 years now and am entertaining the idea of a small turbo build. Reliable and a little more quick.

    I plan to pull my engine out to replace all the lower end bearings, replace the timing chain and tensioner rails etc and of course put in a multi layer head gasket with head studs and get the head/valves machined. I feel this would make a good platform for a small amount of boost.

    Anything over 0psi makes a huge difference because an engine like ours is probably only like 80% volumetric efficient (guessing) so making it 100% is huge. So running maybe like a 3 pound spring in an external waste gate would allow me maybe like 30-40 more horsepower very reliably I would think.

    I'm a BMW Tech and a welder too so I will do all this myself of course and feel as though I could pull off this build for hopefully less than $2000.

    The only thing I'm not sure about is what the best method of tuning would be. I'm looking for something simple that works. I dont need any bells and whistles. Maybe some day if I want a 400hp car for some reason I will of course get serious and go the stand alone route. But for now I just want a little more power that I can still safely apply power in a corner without the risk of roasting the tires upon turbo spool.

    Look forward to whats to come! Thanks for the input you guys have.
    Dan

  • #2
    For many reasons, I would personally never build a budget turbo system to run only 3psi. However, here are some ideas for tweaking your factory tune.

    Step 1: Wideband AFR

    Either of the following components individually will be able to tweak your tune to compensate for 3 psi. I would recommend adding fuel under boost conditions and not retarding any timing since that will yield more power.

    • Rising rate fuel pressure regulator
    • PWM Water/Meth injection
    • MSD Boost Timing Master


    Also, your engine in its factory, well-maintained state will be more than capable of handling 3psi. Head studs and a MLS HG need not apply for your goals.

    Comment


    • #3
      Yeah it's kind of a silly idea, but I feel like it would be fun to do it anyways. Someday I would love to spend $15,000 and make a monster but currently I have other priorities. I still have my wideband from a past turbo build waiting to go in the M3. I had a beastly 240 turbo volvo years ago with water methanol injection and still have the pump and mister and controller etc from that and plan to use that because the methanol will enrichen it and of course take place of an intercooler.
      I want to pull the engine anyways so I can clean it all up (she's pretty oily) and replace the bearings and timing chain.

      Thanks for the help so far! I just started reading your turbo build, and now I am second guessing my little weekend turbo build comparing it to your glorious machine.

      Comment


      • #4
        Oh, and would putting the air flow meter on the intake side of the turbo work accurately enough? If I could easily swap to a MAF that would be nice. I'll have to look into miller MAF's and see if they can do turbo tunes also.

        Comment


        • #5
          If you're the DIY type, you can do a complete Megasquirt system installed and running for under $1K. It's not for the faint of heart, requires a lot of work, but is a complete standalone and can handle fuel, ignition, boost control, etc, etc...
          sigpic
          Track Car Build | COM Sports Car Club

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          • #6
            y not run 7-8psi which is about max with the stock 10.5:1 compression and get a respectable 260HP or so? Seems to be the best bang for your buck. Plumbing an entire Turbo system for 3PSI is hardly worth it.
            "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

            88 M3 - LACHSSILBER/M TECH
            89 M3 - ALPINEWEISS II/SCHWARZ
            91 M TECHNIC TURBO - MACAOBLAU/M TECH
            98 528I SPORT 5 SPEED- SCHWARZ/SCHWARZ

            Comment


            • #7
              Originally posted by Reelizmpro View Post
              y not run 7-8psi which is about max with the stock 10.5:1 compression and get a respectable 260HP or so? Seems to be the best bang for your buck. Plumbing an entire Turbo system for 3PSI is hardly worth it.
              Makes perfect sense.

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              • #8
                Yeah I will probably end up doing that. It's hard to not want more power.

                On a side note, I kind of lost interest in the build for a little while as I got another speed machine. Here is a picture from the lake a few weeks ago.
                Attached Files

                Comment


                • #9
                  Originally posted by KoenigsbergM3 View Post
                  Yeah I will probably end up doing that. It's hard to not want more power.

                  On a side note, I kind of lost interest in the build for a little while as I got another speed machine. Here is a picture from the lake a few weeks ago.
                  Nice...now run 3PSI on that. lol.
                  "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

                  88 M3 - LACHSSILBER/M TECH
                  89 M3 - ALPINEWEISS II/SCHWARZ
                  91 M TECHNIC TURBO - MACAOBLAU/M TECH
                  98 528I SPORT 5 SPEED- SCHWARZ/SCHWARZ

                  Comment


                  • #10
                    Haha operation shit my pants.

                    Comment


                    • #11
                      i am actualy toying the idea of this on my car, but id like to run 5-6 psi on a complete stock motor, how safe is this? should i go with an MLS atleast or should i be fine

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