Not only was the S38 a great performer ... many of them were used as test beds to aid the Le Mans effort. The best BMW engine of all time doesn't actually belong to a BMW at all.

The S14 in the E30 M3, the sublime M88 (and S38 derivatives ... Despite its naturally aspirated engine roots BMW does have some form with turbochargers – it won the F1 title with Brabham ...