Many thanks Gentlemans! As you know in the technical manual on this side the range ends on the R25 version.
Yes, and it also ignores the R24W, which was used exclusively on the Swedish market to meet new CO-based emission restrictions, coming into force there for the 1971 280SL model. The R24W was therefore needed to be much more refined and precise, compared to the other late 280SL pumps, like the R25 (general Euro+ market) and the R24Y (US market). It was also used in the 280SE, and it is therefore easier to find today than eg. the R25, due to the much lower numbers of Euro-spec late 280SL cars sold, compared to the Euro-spec 280SE and even the US-spec 280SL with the R24Y pump.
However, today with the many US-spec 280SL re-imported to Europe, many owners here want to get rid of the US-spec R24Y and replace it with something better and more precise, and here the R24W is a very good choice. Both because it was actually used in the 280SL on the Swedish market for the 1971 model, but also because it can be tuned very accurately to increase both power and fuel economy. So, I am puzzled why it is not mentioned at all in our manual (?).
I don't know much about the R28 though, and it could be interesting to look more into the details of this very late mechanical fuel injection pump for the w108 280SE, introduced just before Mercedes went all-in on the D-jetronic and later K-jetronic across their entire model fleet.
Cheers,
Christian
