Mechta, many thanks for explaining about the need for damping - I had heard of it but never managed to understand. Have you any idea how this problem was tackled in the big engines like the RR Merlin? Very intensive maintenance ( if they ever made it to the specified time ) I should think?
As for the Citroen diesel: it still uses a reduction, as can be seen in one photograph in the article you mentioned. I suppose the belt(s?) take up the vibration in that installation? I remember seeing such a bird at Saint Yann last summer, that gold-anodised aluminium is not easy to forget. Was surprised to learn from the builder that the engine block as such had scarcely been modified.
And just to get the detail right: the French motorway speed limit is 130 km/h - my own country even has 120 km/h - but they are not very strict about it. As I've said before, the further South one goes, the greater the distance between legal and real.