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My 3B Coupe project - Total rebuild

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  • My 3B Coupe project - Total rebuild

    A new year calls for a new project blog
    Here’s the car:-


    Mechanically sound but the bodywork is a bit scruffy, it’s been keyed down both sides and there is rust on the nearside rear wheel arch. Me and Bry bought it about 2 years ago for £1500 planning on turning it into a track day car, but once I started using it on the road I changed my mind. Bry lost interest so I bought his half off him.

    Work completed so far includes
    Samco boost hoses
    All vacuum hoses replaced
    Milltek hyperboost dump valve
    New N75 valve
    PK Motorsport chip from Ebay.de ( 1bar boost with std map sensor )
    18” RS6 replica wheels
    Koni dampers all round
    Polybushed wishbones
    All top mounts replaced
    Porsche 996 front calipers with A8 323 discs, Martinjs alloy mounting brkts
    RS2 FARB
    Cobra Daytona seats

    Rebuild plans
    Build a new high power engine, swap to 6 speed gearbox, change rear diff and both sub frames and upgrade rear brakes. I’m looking for around 400-450bhp but I want as little lag as possible and a huge mid-range, for this reason I’m going down the stroker road. I got an AAB 2.4 bottom end a while ago but when an AAT 2.5 bottom end came up at the right money I took it. The ‘dude’ was in suicide selling mode, bought it for £350, sold to me for £100, bargain!
    I’ve now stripped the block, had it welded to match the 20v petrol head and made a torque plate to suit. Next week I’m going to try and get it bored to 81.5mm and get the deck skimmed.

    Parts I’ve got so far are:-
    AAT 2.5Tdi bottom end, to be bored to 81.5mm
    Sten Parner 155mm rods
    Custom JE pistons
    ARP head & bottom end studs
    RS2 main and big end bearings
    Bosch ‘green top’ injectors
    AAN inlet manifold & water manifold
    New oil pump
    Adjustable alloy cam sprocket
    7A head converted to turbo spec
    ABY front sub frame
    ABY 6 speed gearbox + linkages
    3B rear subframe and diff
    3B single mass flywheel, to be lightened
    New engine, gearbox and diff mounts
    Alloy subframe mounts
    280mm RS4 rear discs
    S6 rear brake calipers
    S8 Rear caliper carriers
    Innovate AFR gauge


    Parts still needed:-
    Exhaust manifold – RS2
    Intercooler – RS2
    Turbo – 3076?
    Exhaust – 3” turbo back from Corey
    Clutch?
    Last edited by AndyP; 1 January 2008, 20:40.
    sigpic
    1991 Audi S2 3B - 2.5 Stroker engine
    1997 A6 2.5TDi quattro avant - C4
    1976 RD250E / 350LC cafe racer

  • #2
    Stage 1 : Rear subframe & diff rebuild.

    I bought a 3B subframe and diff off Sal to rebuild



    I’ve no idea how many miles it had done, but when I stripped the diff there didn’t seem to be anything wrong with it, no play in bearings, no wear on crown wheel or pinion and it was spotless inside



    I made a jig to check the back-lash and even that was spot on, so I decided to put it back together. The way the diff is made means that if you replace the bearings it can be a major PIA to re-shim and get the back-lash and pinion depth right so I’m kind of glad it was OK.


    Subframe, shotblasted, painted and fitted with new diff mounts.


    Rebuilt and painted diff


    Diff mountings and flanges cleaned and painted


    Finished item, ready to fit

    sigpic
    1991 Audi S2 3B - 2.5 Stroker engine
    1997 A6 2.5TDi quattro avant - C4
    1976 RD250E / 350LC cafe racer

    Comment


    • #3


      Cant wait to see this one progress.

      Nice one andy!!
      91 S2 coupé - RIP
      98 S8 - Luxury barge

      Comment


      • #4
        Stage 2 : Preparing block for machining

        This is the AAT block






        Block after welding with torque plate installed, ready for machining
        sigpic
        1991 Audi S2 3B - 2.5 Stroker engine
        1997 A6 2.5TDi quattro avant - C4
        1976 RD250E / 350LC cafe racer

        Comment


        • #5
          After the block is machined, I can do a dry build and make sure all the dimension I gave JE for the pistons are right. Then I need to get a clutch sorted so I can send the bottom end to Southdown for lightening and balancing, so some big bills are headed my way!!
          I'll try and get some pics tomorrow of all the bits ( engine porn! ) I've already got.
          sigpic
          1991 Audi S2 3B - 2.5 Stroker engine
          1997 A6 2.5TDi quattro avant - C4
          1976 RD250E / 350LC cafe racer

          Comment


          • #6
            nice work andy
            can't wait to see this one
            1. SHORT SHIFT KIT
            2. PORSCHE CAYENNE CALIPERS
            3. H & R SPRINGS
            4. BILSTEIN SHOXS
            5. NEW BUSHES AND HP2 STRUTS
            6. UPRATED HIGH OUTPUT COIL PACK
            7. ,3" turbo back s/s/ exhaust
            8. fmic fitted

            Comment


            • #7
              Nice work Andy, hope to see you on track sometime!
              Cheers'en, AndyC
              1994 ABY Coupe - Projekt Alpinweiss

              Comment


              • #8
                Loving your work there fella.

                Fancy coming over and prepping my subframes etc?

                Cheers,

                Steve
                The Perfectionist
                sigpic
                Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

                Comment


                • #9
                  Stage 3 : Cylinder head

                  This is the 7A head that I got from Spink ( Cheers James ), he had it converted to Turbo spec by adding the hall sensor mounting and machining the water jacket to fit the ABY/AAN water manifold.

                  7A head – Zero cracks!


                  Water manifold machining


                  Hall sensor mounting welded on and machined


                  The head has now been stripped and is with Corey for a de-coke, skim, new valve guides and valves and some ‘massaging’ of the ports.
                  He’s also working on a mod to let the big turbos ( 3071/3076 ) spool up much quicker, but I’ll let him tell you about that when it’s complete:mischeif:
                  sigpic
                  1991 Audi S2 3B - 2.5 Stroker engine
                  1997 A6 2.5TDi quattro avant - C4
                  1976 RD250E / 350LC cafe racer

                  Comment


                  • #10
                    AndyP, what will your choice of cams be?

                    Looking to do a similar thing, that is why I wonder....

                    Good luck, nice to see people doing it right!

                    Johan

                    Comment


                    • #11
                      great photos Andy, prop ones look very familar My replacement rear subframe is in the garage still waiting for a blast and paint and hopefully it will be bolted up with my new prop sat gathering dust in the garage.

                      Good luck with the project!!!
                      David
                      sigpic

                      1992 3b S2 Coupe

                      Comment


                      • #12
                        andy are you using standard diesel crank standard size rods and lowered piston pin pistons ?

                        Comment


                        • #13
                          Andy lovely project to work on, especially with the plans you have for the car. Looking forward to seeing the finished result. Would you like a gallery area for the project too?
                          Greg

                          S2Forum.com Administrator & Webmaster

                          '93 Coupe with a few tweeks

                          Comment


                          • #14
                            Originally posted by volcano rs View Post
                            andy are you using standard diesel crank standard size rods and lowered piston pin pistons ?
                            Crank is the 95.5mm Tdi crank with Parner 155mm rods, JE pistons to suit. I want to keep the CR close to std as I'm not planning on running massive amounts of boost, so it should be in the high 8's. This will be proven when I do a dry build and take some real measurements.
                            sigpic
                            1991 Audi S2 3B - 2.5 Stroker engine
                            1997 A6 2.5TDi quattro avant - C4
                            1976 RD250E / 350LC cafe racer

                            Comment


                            • #15
                              very nice i'll be watching this with interest

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