I hope this message finds you in good health?
I had a question: can you identify, based on the engine number, if the engine with - ATR M28/42 81K0698 already has the reinforced heads?
I could not find anything about it on your extensive website.
The background of the question is that I'm considering a S4 from 1988 with a replaced engine. I want to know if this is the stronger version already.
kind regards and always full compression on all cylinders :)
The M28/42 81K0698 is from 1989 S4
M28.42 5L 8 1989 Porsche 928 S4 M249 (235Kw / 319Hp) 81H 81K05001 >> 10000
M28.42 5,0L 8 1989 Porsche 928 S4 M249 (235Kw / 319Hp) 81H 81K05001 >> 10000
The service bulletin is not very specific (canít be because they are made before actual production and during model year 1989 the change was made). So that is no help.
But PET says there are two numbers:
928.104.014.02 up to 81K05238 and 928.104.014.03 starting 81K05239
The engine you inquire about is 81K0698, and I presume (!) that the latter one is the stronger head with the extra 20mm around the bearing surfaces for the cylinder bolts.
Hope that helps.
1992 Porsche 928 GTS Midnight blue