Mike Hall, former Cosworth Director and designer of the BDA engine gets together with John and reminisces over old times. Mike shouldered the entire design of the engine as Keith was pre-occupied with F1, this led to Cosworth's first engine to use belt drive to its camshafts. It was based around the Ford Kent cylinder block and combined with four valves per cylinder produced very good gas flow. This set the standard in the 70s which other manufactures took many years to match. The BHP per litre of the BDA is not far short of what can be achieved now with present day technology which is a credit to Mike Hall's design.

Cosworth solidified its association with Ford in 1969, by developing a double overhead camshaft (DOHC) 16-valve inline four-cylinder engine for road use in the Ford Escort. Working from the Kent block, Cosworth created a 1601 cc BDA for homologation purposes. The camshafts were driven by a toothed belt developed for Fiat 124, hence the name BDA, literally meaning "Belt Drive, A type". Running in Group 2 and Group 4 on either rallying or touring car racing, this engine could be enlarged to a maximum of 1975 cc. The nominal homologation at 1601 cc capacity meant that BDA-engined cars competed in what was usually the top class (1600 cc and up) so were eligible for overall victories rather than class wins.