R11 & R12 injection Pump Differences

[mistertj]

Does anyone know what the pump differences are between a PES6KL70/120R11 and a PES6KL70/120R12. Also, are they interchangeable? I have an R11 in my 230SL and was looking for a spare ut all I find are R12's.

[Shvegel]

The R12 pump is for a 300(3.0 Liter) sedan:

https://www.sl113.org/wiki/Fuel/Injection

[mistertj]

Thank you. The R12 sure looks like an R11 from the outside.

[mbzse]

The R12 sure looks like an R11 from the outside

Certainly so. But internal characteristics are different between the types. The FI pump is set up in the factory so that it is tuned to the type of car. The W112 (and W109) is a heavier vehicle.

[Shvegel]

They very well may be the same pump except for the space cam and the Tuning but it is impossible to tell without detailed manuals.