TDIMeister
Phd of TDIClub Enthusiast, Moderator at Large
The GT40 I spec'ed out was already too big for 400 HP in the 1.9 TDI; the S200 takes big to a whole other level. While it's a stretch to make 400 BHP from a 1.9L 4-cylinder TDI, I could definitely see a realistic possibility to use either turbo to make that power level in a 5-cylinder TDI.
But as GoFaster warned, care must be taken in the boost control to prevent the possibility of the boost rising to sufficient levels to cause the engine to go BOOM!
Using an R5 engine as a baseline, I would lay out the hotside like in the BMW x35d, meaning in parallel with the stock GT22V used in the R5. The pair of turbos will also be connected to a large capacity external wastegate that begins open at a fixed EMP, say, 2.5 bar and fully open at, say 3 bar. The turbine of the LP turbo would have to be dimensioned for A/R ratio such that with its characteristic boost threshold, it would be impossible for it to spool with the 3 bar EMP limit to make enough boost at the low-end RPM for damaging surge and boost pressures to occur.
The N75 still controls the VNT on the GT22V, but a MAP sensor that will operate over the full range of MAP will be required (I recall DIESEL DAZZLER telling me there's a GM part that goes to 4 bar or something...). Remapping would obviously be necessary.
On the cold side, the inlet of the LP turbo is connected to ambient, the outlet to the HP turbo and then off to the IC.
400 HP can be achieved in an R5 using no cheaters with 3.5 bars (50 PSI)of boost (4.5 bar absolute) if maximum power is produced at 4750 RPM.
BTW, the map of the S200 suggests that is has a ported shroud. It has a wide flow range between the surge- and choke lines, while sacrificing some efficiency.
But as GoFaster warned, care must be taken in the boost control to prevent the possibility of the boost rising to sufficient levels to cause the engine to go BOOM!
Using an R5 engine as a baseline, I would lay out the hotside like in the BMW x35d, meaning in parallel with the stock GT22V used in the R5. The pair of turbos will also be connected to a large capacity external wastegate that begins open at a fixed EMP, say, 2.5 bar and fully open at, say 3 bar. The turbine of the LP turbo would have to be dimensioned for A/R ratio such that with its characteristic boost threshold, it would be impossible for it to spool with the 3 bar EMP limit to make enough boost at the low-end RPM for damaging surge and boost pressures to occur.
The N75 still controls the VNT on the GT22V, but a MAP sensor that will operate over the full range of MAP will be required (I recall DIESEL DAZZLER telling me there's a GM part that goes to 4 bar or something...). Remapping would obviously be necessary.
On the cold side, the inlet of the LP turbo is connected to ambient, the outlet to the HP turbo and then off to the IC.
400 HP can be achieved in an R5 using no cheaters with 3.5 bars (50 PSI)of boost (4.5 bar absolute) if maximum power is produced at 4750 RPM.
BTW, the map of the S200 suggests that is has a ported shroud. It has a wide flow range between the surge- and choke lines, while sacrificing some efficiency.