A genuine one-off in Jaguar's production history, regulatory problems and a change in the marque's internal policy put paid this automobile's racing career before it had even begun. Perhaps cursed from the outset, it would be destroyed in an accident during road-tests in 1971 after a long period of inactivity. Despite this second setback, the XJ 13 was to be meticulously restored two years later and remains in excellent condition to this day.
Jaguar knew that the XK engine had reached its limits. In its final 3.8 liter engine competition version with the wide angle 35/40 cylinder head and indirect injection, its maximum power output reached almost 320 hp. In comparison, the final street legal version, which had a 4.2 liter engine with a straight port cylinder head, produced only a timid 265 hp.
The design office set to work on a new engine, which would first be tested around mid-1964. A monstrous mutation of two XK 6 cylinder engines joined together and topped with two separate cylinder heads, this quadruple cam-shaft 5 liter V12 was capable of producing 500 hp at 7500 rpm. The development of this formidable block would continue throughout 1965.
In the strictest secrecy, aerodynamics expert Malcolm Sayer, the visionary behind the C-, D- and E-Types, would oversee the conception of an alloy monocoque roadster (barchetta) with a centrally mounted engine structure. In keeping with true aeronautic tradition, this bodywork was assembled using rivets and its shape was subject to numerous aerodynamic lift and drag coefficiency calculations, while its structural conception was not passed over with the use of multiple box beams.
To be continued...