I have seen a lot of numbers bandied about on this forum regarding the maximum boost pressures that are factory specified for the 617 engines (300D & SD). It seems that most people are going for .9 or even 1.0 bar when adjusting their wastegates. This is either a mistake, or I am barking up the wrong tree here.

The 123 service CDs contain a graph showing the boost/RPM relationship. This graph shows a PEAK pressure of about .75 bar at 3200 RPMs, and this is at the upper end of the specified window of operation. Boost actually falls off a bit after that, and ends up at around 730 mbar at 4000-4200 RPMs. Now, of course this is from the U.S. spec CD.

Now, I have also read an opinion that these engines were under-spec from the factory for emission reasons. This would leave me to think that perhaps the specified boost is higher for European versions of this engine. But, if memory serves me correctly (and I am really not sure about this) I believe that these turbo diesel engines were not installed in these cars in Europe.

Now, I need to ask about the spring retainer on the Garrett turbo….(another posting).

Thanks Everyone!