Why were Imps & Saabs chosen for outfits? & not Ford or BMC/Leyland etc?
Choice I suppose
The Saab lump was iron too but very compact compared to most other car derived motors. There were other options used too, VW Beetle, Honda S800, NSU 1200, Coventry Climax, DKW, Koehler (ex snowmobile), Konigs of course, one French driver played around with Panhard and Citroen engines.
The first Imp engine that I recall was driven by Vic Phillips in an outfit called Nerus Impetus in the mid 60s. Nerus at that time xere very successful in tuning rally Imps so bits were available, same goes for Ford and BMC lumps. VW powered chairs probably arose from a dragster bike that used a Beetle engine, that of Clive Waye in his DragWaye Bike as I recall none used before then. Ray English campaigned an NSU outfit for a good number of years both in open racing and latterly with CRMC, the favourite unit was from the NSU 1200TT version. When they went they were quite quick but somewhat temperamental.
Unfortunately modern racing has none of this individuality, ingenuity and engineering skills where the majority of outfits were home built, its passing I mourn. Today the F1 class is virtually a one make series of LCR/Suzuki, the F2s have a variety of chassis by different makers but dominated by Honda power. Oh well, that's progress