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Birdman's B204 MINI (Mid Engine RWD)

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  • Birdman's B204 MINI (Mid Engine RWD)

    B204 MINI (Mid Engine RWD)

    Starting this build thread at last. Have had the dream of building this car for a long while and have been acquiring various parts in readiness. The concept is to build a car that can be drag raced and hopefully achieve a 10second ¼ET and allow track work / possibly hillclimb. Main point is to build a crazy car that delivers real fun without breaking the bank.

    Requirements:
    • Must be cheap to build. £2 – £2.5K
    • Must be fun to drive and put a smile on my face when I drive it.
    • Easy to tune to higher HP. B204 = Loads of potential. Downside – it is heavy.
    • Easy to maintain. Could be difficult with rear engine install, but engines reliable.
    • Make great noises and some flames.
    • Good ¼ mile ET. With weight over rear wheels and lots of power. - I believe it is totally possible.
    • Reasonable Handling for track or hill climb. Weight distribution will not be ideal and so will work on suspension setup to achieve.
    Whale Oil Beef Hooked!
    (use Irish accent)

  • #2
    Therefore:
    • Non road legal to keep costs and weight down – (no mot, tax insurance etc).
    • Mid Engine RWD. Weight over rear wheels to put power down for 1/4mile.

    Parts that I have now:
    • SAAB B204.
    • No expensive standalone ECU required – have 2 reprogrammed ECUs.
    • Cheap Gearbox – F23 from Vectra 2.0SRI. Cable Shifter assembly.
    • Short shifter.
    • Front Roll Cage Rollcentre / Rear Autograss Cage setup carrying Powertrain.
    • Rear trailing arms setup like Z Cars.
    • Fully adjustable coilover suspension to put the power down.
    • Hydraulic Handbrake.
    • Carbon Dashboard.
    • Front and rear anti roll bars..
    • Wheels & Tyres 13” Minilites + R888s.
    • Uprated Intercooler.
    • Forge Dump Valve.
    • Remapped ECUs for 270HP stage 3 and 360HP Stage 5
    • Siemens Deka 875 Injectors.
    • 3 bar MAP Sensor.
    • GT2860 RS Chinese copy turbo.
    • 3 bar map senssor.
    • Saab T7 APC
    • Adjustable wastegate actuator.
    • ATL Race cell fuel tank.
    • Custom Manifold and external waste gate.
    • 3 inch downpipe
    Whale Oil Beef Hooked!
    (use Irish accent)

    Comment


    • #3
      Starting Out:

      I am using a rough old Autograss rear cage to develop the rear end package in kit form. The prototype frame will be used, but I may make a better version once proven. I have no room for an extra mini body shell at present, but I know that the datum points on the frame are correct as it came out of a mini and I can take some basic measurements from my other mini.
      When the rear frame and setup is complete I will buy a shell and set about joining the rear cage to a full Roll centre cage that I have. Costs so far have been pretty low. Buying the engine without a donor car has saved quite a lot, but I’m sure some costs will creep back in. At that stage I will clean up the engine, do a balancer shaft delete, new head gasket and timing chain. I will probably also fit Volvo T5 valve springs. The Saab lump has been installed into so many Vauxhall conversions over the years, that there is a lot of info out there to assist me. Trionic 5 ECU is tuneable through opensource T5 Suite software, but I already have two mapped ECUs. It is cheap power.

      I’m thinking to keep the driveability for both ¼ mile and track work, it will be best to have the turbo produce up to 360HP and use my nitrous kit to give the rest to 500 HP. That way the gearbox may hold up better and I won’t have a laggy all top end setup. Target weight is 600 – 660 kgs.

      For the front end of the car, I intend to use std mini front subframe with adjustable bottom arms. Metro hubs and MGF brakes to keep costs down. I have triple adjustable coilovers all round and front and rear anti roll bars. Radiator will be at the front along with fuel tank. Intercooler in the rear to keep pipe runs short. F23 gearbox is a common swap and is cable operated with hydro clutch. I will get long cables made up for the gearchange, as the VX220 is this way I believe.

      Initially I will use the standard GT25 Turbo with the 270 hp map, which still should be great fun. Then upgrade to the other setup I have later. I will make up another downpipe for the basic install. No silencer required for drag work, but I will add one to meet track regs. Probably have a diverter valve.
      Whale Oil Beef Hooked!
      (use Irish accent)

      Comment


      • #4
        Currently:

        I have chopped the frame a little and have almost got the engine and transmission positioned to where I want it. I am waiting on driveshaft parts, so that I can fix my trailing arm pick up points and am fabricating engine and gearbox mountings. It looks as if I will have clearance / access to most parts when installed, just waiting to check on important driveshaft angles etc. Hope to start fitting some mounts this weekend.


        Whale Oil Beef Hooked!
        (use Irish accent)

        Comment


        • #5
          Speed / Gear Calculations:

          F23 GEARBOX CODE SR FD 3.737 VECTRA B X20XEV
          Tyres 205x60x13 R888
          SAAB B204
          RPM LIMIT 7000:

          Tyre Circumference = 1810.18 mm
          1st Gear = 56.88 km/h - 35.26 mph
          2nd Gear = 100.62 km/h - 62.38 mph
          3rd Gear = 150.92 km/h - 93.57 mph
          4th Gear = 208.24 km/h - 129.11 mph
          5th Gear = 251.48 km/h - 155.92 mph


          RPM LIMIT 6500:

          Tyre Circumference = 1810.18 mm
          1st Gear = 52.81 km/h - 32.74 mph
          2nd Gear = 93.43 km/h - 57.93 mph
          3rd Gear = 140.14 km/h - 86.89 mph
          4th Gear = 193.36 km/h - 119.88 mph
          5th Gear = 233.52 km/h - 144.78 mph

          Whale Oil Beef Hooked!
          (use Irish accent)

          Comment


          • #6
            Started by doing some upgrades to my workshop.... 20170819_095307.jpg20170819_095340.jpg
            Attached Files
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            • #7
              ...
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              • #8
                Meanwhile in the garage I roughly put together the Rollcentre cage and Autograss rear cage and with some tape ​ put the carbon dash in place to see what it could all start to look like...
                Whale Oil Beef Hooked!
                (use Irish accent)

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                • #9
                  ... 20171111_123826.jpg
                  Whale Oil Beef Hooked!
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                  • #10
                    Sourced the SAAB B204 engine and gearbox from a Saab 9000 with engine loom , ancillaries etc delivered for £200 Saab gearbox no good to me so will sell that, as they are getting more rare now. It is a rod change box and I did not fancy making up complex sloppy gearchange mechanism. Got a forge dump valve dirt cheap.
                    Whale Oil Beef Hooked!
                    (use Irish accent)

                    Comment


                    • #11
                      Engine turned over nice on starter and gave good compression readings.

                      Bought some wheels and tyres from a Caterham. Minilites with 185 60 13 fronts and 205 60 13 backs all with R888s £100 the lot. 20180421_115804.jpg20180422_153233.jpg
                      Whale Oil Beef Hooked!
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                      • #12
                        Initially put the powertrain onto a trolley to see if there was a good chance of it fitting. It did, but the Saab box is a little bit too long, so that made my mind up to get a Getrag F23, which is used in most Vauxhall conversions, is cable gearchange and gives me 2 more inches space for trailing arm movement. 20180319_200231.jpg20180319_200323.jpg
                        Whale Oil Beef Hooked!
                        (use Irish accent)

                        Comment


                        • #13
                          Bought some trailing arms from a autograss mini pickup running Chevrolet V8. Was hoping to use the sliding spline shafts and hub setup and ditch the actual arms, which weighed a ton. Shafts had been handling 350+ hp but unfortunately they were just not going to work. So I am refurbing them and will sell them off. I got them very cheap. I should make a few quid on them me thinks.. 20180324_113253.jpg20180409_180408.jpg
                          Whale Oil Beef Hooked!
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                          • #14
                            Anyway, you can see that this setup was getting way too wide at the back 20180409_180449.jpg20180324_121841.jpg
                            Whale Oil Beef Hooked!
                            (use Irish accent)

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                            • #15
                              But had a little mock up with those arms, just for a laugh to get the total width. At least it proved I would need different trailing arm and driveshafts.. 20180422_160441.jpg20180422_161455.jpg
                              Whale Oil Beef Hooked!
                              (use Irish accent)

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