Jaguar V-12 Automobile User Manual

october 2007
Performance Builder’s Guide:
Jaguar E-Type Series III V-12
opular wisdom states that of all
the E-Type variants built between
1961 and 1974, the first series of
lighter, triple-carbureted straight-six cars
make the best racers; the V-12-powered E-
Types built between 1971 and 1974 were
too plush, too heavy, too complex. While
the Series III cars, both Open Two Seaters
(OTS) and 2+2 Fixed Head Coupes (FHC),
may have been larger and less agile than
their short-wheelbase predecessors, their
12-cylinder engines featured impressive
engineering and a torquey, smooth power
delivery, and they still wore aerodynamic
bodywork considered by some to be the
most beautiful of the era. Although the
steel-roofed FHCs are a natural choice for
high-speed race cars, OTSs perform admi-
rably with judicious body reinforcements,
and both are virtually guaranteed to be the
prettiest cars on the track.
The design of this company’s road-going
5,343cc, single overhead-cam 60-degree
V-12 was influenced by the 4,994cc V-12
in 1966’s stillborn XJ13 Le Mans racer.
This aluminum-bodied car’s mid-placed
engine had an 86.87 x 69.85mm bore and
stroke, and its Brico pistons and Dykes
piston rings were moved in their cast-
iron dry cylinder liners by a nitrited steel
seven-main-bearing crankshaft and forged,
polished connecting rods. Dual overhead
cams actuated the valves, and dry sump
lubrication and mechanical Lucas fuel
injection circulated the fluids. The final
results of the XJ13 engine’s tuning were
502hp at 7,600 rpm and 386-lbs.ft. of
torque at 6,300 rpm.
Using lessons learned from the XJ13
engine, Jaguar developed the Series III E-
Type’s V-12 to maintain their customary
level of power in the face of ever-stiffer
emissions regulations. Smooth and bal-
anced, the aluminum block and head V-12
featured a number of performance-biased
components, including high-flow, flat-top
combustion chambers with optimally situ-
ated inlet and exhaust valves, seven main
bearings and replaceable, cylinder-cool-
ing, cast-iron wet-sleeve cylinder liners.
This engine would gain fuel injection and
be redesigned twice before V-12 produc-
tion ceased in 1996, the first time in 1981
when it became the H(igh) E(fficiency) with
a redesigned “swirl” combustion chamber
design, and the second time in 1994 when
the HE was stroked to 6.0 liters of displace-
Considered by many to be overbuilt,
the Jaguar V-12 can withstand significant
cylinder boring, notably raised compres-
sion and is adaptable to numerous fuel
delivery solutions. Although Jaguar may
have intended their often air-conditioned,
power-assisted Series III cars to be Grand
Tourers, as opposed to the pure sports cars
of the first E-Type iteration, there are some
enthusiasts who feel otherwise. Stew Jones,
president of Stew Jones Restorations in