SHANNON HERAUD’S MK 1 ESCORT RUNS ONE OF AUSTRALIA’S COOLEST ENGINES – A WILD, 600 HP
BLOWN 253 THONGSLAPPER
STORY IAIN KELLY PHOTOS SHAUN TANNERW
HILE many turn their nose up
at Holden’s 253ci V8 in favour
of offerings with more cubes,
Shannon Heraud has history
with GM-H’s baby V8, having used and abused
them in his ex-burnout Torana sedan.
During the planning stages of the build of his
killer Mk1 Escort burnout car (SM, Aug ’18),
Shannon was looking for something unusual
and affordable to power it. “I had the motor left
over when I retired the Torana, so I thought, why
not? It just progressed into seeing what we can
get out of this little V8.”What he has ended up with is an amazing
piece of street-machining engineering, using
plenty of nous to get a killer result for minimal
fiscal outlay. “I was given the block years and
years ago by my mate Charlie Grieve, who
did skids in his Warwick Yellow HK Monaro,”
explains Shannon.
The four-bolt bottom end uses a crank that
Shannon thinks is from an 80s Holden blue
motor, though he can’t remember. “It isn’t
anything special, and it hasn’t had anything
special done to it,” laughs the Victorian. Scat
H-beam forged rods are fixed around the crankwith ARP 2000 bolts, while forged JE pistons
squeeze a boost-friendly 9.0:1 compression
ratio. “To keep it alive, I make sure I do lots of
oil changes, and always make sure the engine
has oil pressure,” Shannon says.
As part of a recent freshen-up, Shannon went
with a new custom-grind bumpstick from Clive
Cams. “It’s still a flat-tappet hydraulic cam, and
it is in the 250-260-degree range at 0.50, with
about 600thou lift,” he says. He also upgraded
the rest of the valvetrain to suit. Crane Cams
EDM hydraulic lifters to suit a small-block
Chev got a run, along with shaft-mount JeselSportsman rockers with a high-lift 1.7 ratio,
and thicker^3 / 8 -inch Trend pushrods that won’t
deflect under the strain of 7000rpm.
“The heads are basic early HQ-style iron red
heads that I hand-ported,” Shannon says. “I
opened them up in the throats a fair bit, gave
them a five-angle job, and machined them out
to fit the bigger Isky valve springs.”
While most of the engine is quite
understated, one piece of exotica that stands
out is the four-stage Barnes Systems dry-
sump oil pump and custom oil pan sitting on
the bottom of the donk.“The sump is a custom pan built by an ex-HRT
engineer about 20 years ago while he was still
working there,” says Shannon. “It was built in a
similar style to the Group A dry-sump set-ups.”
Under the GM 4/71 blower and Enderle
injector hat is an old Redline tunnel-ram intake
that Shannon whipped the plenum off and
replaced with a unit he custom-made to fit the
air pump. At its base are eight Bosch 1000cc
injectors feeding straight methanol into the
253, while another two squirters are hidden
inside the bug-catcher hat, along with an LS1
throttle position sensor sending info back tothe Autronic SM4 ECU.
For ignition, Shannon uses the SM4 paired
to an Autronic 500R CDI box, with a four-point
magnetic crank trigger to tell the ECU where
the crank is in each cycle. The dizzy is retained
to act as a cam sync for full sequential EFI,
and to fire the spark from the coil to the leads
without the need for ugly individual coil packs.
Spent gasses tumble out of 1^7 / 8 -inch primary
pipes that wind up at 3.5-inch collectors, and
were originally fitted to a very famous Victorian
burnout car: “The extractors I bought years
ago, and they started off on Clint Ogilvie’sRUNNING 9PSI ON THE JOHN SIDNEY ENGINE DYNO, THE ‘LITTLE
THONGSLAPPER THAT COULD’ MADE 600HP AT 7000RPM