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  • rear down pipe block off?

    Whats the best way to gp about blocking off the spot of the downpipe on the rear manifold?

    Anyone have any sucess with welding a plate over it? or would i be better off to bolt the plate on?
    Mr_Efficiency

    90 Grand prix - Lawn ornament
    Black, 3.1, 5 speed
    Future holds: Striped and then scrap yard

    97 Cavalier - Stock car
    Red/Black, 2.2 OHV, 5 speed, fully tubed bumper to bumper, 6 point cage with halo, fuel cell, race seat, 5 pt harness.... a race car
    Future holds: Just more trophies

    New project on the way: 88 S10 reg cab, short box, 5 speed.
    Future holds: Built 2.8 hybrid, Stealthy flat black, a drop until i have no more ugly wheel gap

  • #2
    i think zzperformance uses a block off plate on their turbo kits.

    S
    Shane "RedZMonte"
    2004 Corvette Z06 Commemorative Edition -VIRGIN
    1995 Monte Carlo Z34 14.38@101mph, 331hp/355tq
    -Turbonetics T04E Super 60 Turbo, 2.5" Borla Catback, OBDII, 42.5# Injectors
    2004 Subaru WRX STI -Lightly Modded (SOLD)
    1994 Lumina Z34 -VIRGIN (SOLD)
    1992 Lumina Z34-VIRGIN (RIP)
    1992 L67 Lumina Z34 (SOLD)
    1990 Turbo Grand Prix (SOLD)

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    • #3
      This hasn't been done much in the 60 degree world. The 3800 guys use their downpipe exit as a place to mount a wastegate on a block off plate. Welding would work. I would personally prefer a bolted on plate.

      Tim
      1995 Z34 - T04E "60" trim, 42.5 lb/hr injectors, AEM WBO2, FFP UD&DB, 3" exhaust, 2800 stall, shift kit, tranny cooler, Powerslot, Hawk HPS, rear disc conversion, KYB, Eibach, HMS F&R STB, Fittipaldi Force 18" wheels, big stereo, lots more coming eventually...
      325 whp 350 lb-ft

      Comment


      • #4
        thats an interesting idea with the waste gate, except the fact that the other 3 cylinders are still passing the turbo on the way to the wastegate, but it would still work.

        I think I'll just bolt a plate on and then weld it, that way I know i have a really good seal and if it cracks its not a huge deal cause the bolts will hold it on.
        Mr_Efficiency

        90 Grand prix - Lawn ornament
        Black, 3.1, 5 speed
        Future holds: Striped and then scrap yard

        97 Cavalier - Stock car
        Red/Black, 2.2 OHV, 5 speed, fully tubed bumper to bumper, 6 point cage with halo, fuel cell, race seat, 5 pt harness.... a race car
        Future holds: Just more trophies

        New project on the way: 88 S10 reg cab, short box, 5 speed.
        Future holds: Built 2.8 hybrid, Stealthy flat black, a drop until i have no more ugly wheel gap

        Comment


        • #5
          Depends on the car/turbo downpipe routing. Tried a bolt on cover on my beretta, but tore up my down pipe wrap trying to get it past the stupid bolts...took it all off and had it welded. But havn't put the turbo back on since so cant tell ya if it'll hold.
          You may or may not know 10 times what i do.
          ASE Master certified. Just means I can take tests. GM ASEP Graduate.
          95' Z26, ported/cammed 3400/3500, OBD2, 282, T3T4. Boxes almost all empty..

          Comment


          • #6
            i didnt think a stock rear manifold was mean to flow in that direction.

            Comment


            • #7
              welding cast iron sucks...

              if you could find a TGP rear manifold or maybe use a 3.1's front manifold on the rear it might work out a little better.. I have seen people find the 1st design 3100 rear manifolds and weld over the downpipe.. (bottom one in this pic)



              not pretty but it seems to work.
              Past Builds;
              1991 Z24, 3500/5 Spd. 275WHP/259WTQ 13.07@108 MPH
              1989 Camaro RS, ITB-3500/700R4. 263WHP/263WTQ 13.52@99.2 MPH
              Current Project;
              1972 Nova 12.73@105.7 MPH

              Comment


              • #8
                Originally posted by Superdave View Post
                welding cast iron sucks...
                That's why you pay someone else to do it :P
                You may or may not know 10 times what i do.
                ASE Master certified. Just means I can take tests. GM ASEP Graduate.
                95' Z26, ported/cammed 3400/3500, OBD2, 282, T3T4. Boxes almost all empty..

                Comment


                • #9
                  how is the one on top better? the newer one has wider ports but doesnt seem like it would flow that well in that direction.

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                  • #10
                    That image was borrowed from another site. It means it's better for N/A flow. The pic was posted just to show the lower manifold in the picture which would be the best style to block off, as the other log style exits in the center. Hack that style's exit flange off and weld a flat plate up.
                    sigpic New 2010 project (click image)
                    1994 3100 BERETTA. 200,000+ miles
                    16.0 1/4 mile when stock. Now ???
                    Original L82 Longblock
                    with LA1, LX9, LX5 parts
                    Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

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                    • #11
                      I cant get a TGP rear manifold cause 1, im in canada so there scarce and 2, I'm using a 3400 top end so it wouldnt bolt up anyways. Also a front manifold wont work on the rear cause of the way the cylinders are stagered it would only bolt up with the opening pointing at the timing side of the engine.

                      I have the exhaust manifold in the top of the pic, and yes the one port goes the wrong way. What is the bottom one off of? is that a pre 2000 3100 exhaust manifold? It looks like it would work out a lot better.
                      Mr_Efficiency

                      90 Grand prix - Lawn ornament
                      Black, 3.1, 5 speed
                      Future holds: Striped and then scrap yard

                      97 Cavalier - Stock car
                      Red/Black, 2.2 OHV, 5 speed, fully tubed bumper to bumper, 6 point cage with halo, fuel cell, race seat, 5 pt harness.... a race car
                      Future holds: Just more trophies

                      New project on the way: 88 S10 reg cab, short box, 5 speed.
                      Future holds: Built 2.8 hybrid, Stealthy flat black, a drop until i have no more ugly wheel gap

                      Comment


                      • #12
                        ill trade ya rear manis its from a early 3100, say 95 or 96 around there.
                        sigpic

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                        • #13
                          I welded a plate on my rear manifold for my first ghetto turbo setup. It worked well and I had no issues. It wasnt an ideal setup by any means tho.

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                          • #14
                            I had an old 80 Cutlass Calais that had a 307 that I put true duals on. The set of manifolds that got tracked down for me were made for a factory crossover and single exhaust, but the side for the in from the other bank had a plate welded to it like what Chris88CL mentioned.
                            -60v6's 2nd Jon M.
                            91 Black Lumina Z34-5 speed
                            92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
                            94 Red Ford Ranger 2WD-5 speed
                            Originally posted by Jay Leno
                            Tires are cheap clutches...

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                            • #15
                              I'm just going to use the "ghetto" welded block off until I can get some turbo headers made. *looks at FF then at loner666*
                              You may or may not know 10 times what i do.
                              ASE Master certified. Just means I can take tests. GM ASEP Graduate.
                              95' Z26, ported/cammed 3400/3500, OBD2, 282, T3T4. Boxes almost all empty..

                              Comment

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