Remember that the turbo is controlled by the EDS computer on this car, just like it is on the 2.5 Turbo engines. The wastegate is normally open and the computer commands it to shut to build boost. If it detects any fault (like the EGR not working) it will go into limp mode and cut boost.

Stock the engine should make almost 150 HP and about 250lb/ft of torque off the line. The W140 is heavy, but it should still move decently with the 3.5.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.