Formula Junior used just about every production engine from a saloon car, around 1,000cc, most of them in the UK, however did come from Ford, the Anglia 105E, or the 948 BMC engine from the Morris Minor, FIAT and Auto Union/ DKW, 2 stroke, engines were quite popular on the continent. They really were quite highly tuned in 85 to 100 bhp was usual from the Fords, BMC's and 2 strokes with the 1100 Fiat engines making 120bhp, that would be good for a normally aspirating engine today. Bear in mind there was no Formula 2 then as Formula 1 had taken over as the 1.5 ltr Formula then with NA engines making 175-200bhp, hence formula junior had to fulfil two roles as both an entry level to single seaters and a feeder to F1. So it wouldn't have been the big jump from Formula Junior to F1 as it would be from FF to F1 today