It’s always intrigued us how HSV use the name Senator to represent one of its
top-line performance models. We’re supposed to think of an all-powerful
figure that demands quivering worship and respect from everyone around. But, if
you’re like us, you’ll think of a rotund aging gentleman with an air of
arrogance and a bad hair piece.
Rest assured, this particular HSV Senator – with 501hp (374kW) at the wheels
– represents the former!
Owned by Geoff Taunton, this 2003 VYII Senator Signature was purchased with
the intent of creating a luxury car with the performance of the ‘teaser’ 427ci
Monaro that never went into production. Yep, Geoff is a man with big plans – and
the finances to back them up. So, not long after purchase, the Senator was
dropped off at PowerTorque in Brisbane for what’s best described as a total
The platform for this spare-nothing engine build is a 427ci (7-litre) C5R
block which is designed for motorsport and boasts six-bolt main bearing caps.
And, no, it’s not a cheap item! Add to this an aftermarket stroker crankshaft
and you’re talking a total 442ci (7.2 litres) displacement. Geoff has also opted
for Lunati rods and JE forged pistons which prove a compression ratio around
10.5:1 – low enough to enable the engine to run on pump fuel.
On top of the C5R block you’ll find LS6-spec cylinder heads which have been
extensively ported and polished. Upgrade valves, valve springs, retainers and a
double row timing chain are also installed. A plenty serious Comp camshaft teams
with Yella Terra 1.7:1 rockers to provide wild valve timing and lift. You
wouldn’t call the valvetrain conservative...
The entire engine assembly has been blueprinted and crack-tested. An ARP stud
kit, high volume oil pump and custom sump also help keep the big banger pumping
And check out the engine’s crowning glory – a magnificent eight-throttle
Geoff bypassed the cheaper aftermarket intake manifolds to be one of the
first in Australia to use the magnificent Harrop Hurricane manifold. This
particular Hurricane set-up comprises eight 55mm diameter throttles (with
individual adjustment to aid tuning), individual ram-tubes and Harrop’s optional
‘Installation Kit’ with two plenums, twin pod air filters and an intake tray
that shields under-bonnet heat. Geoff has also added a snorkelled VZ Monaro
bonnet to provide extra airflow to the filters.
Interestingly, Geoff had the chance to drive the car with and without the
Harrop manifold and says it made a tremendous improvement in terms of throttle
response and refinement. The monster camshaft currently being used gives a
pretty lumpy idle – but the same cam used with the standard manifold was way too
bad-mannered for street use.
The new eight-throttle induction system employs MAP load sensing and the
management system is tuned via VCM Suite. Injectors are massively upsized over
standard and, interestingly, the standard fuel pump is up to the job. The
ignition system also remains standard.
On the exhaust side, the Senator breathes through 1 7/8-inch 4>1 DiFillipo
headers leading into a twin 3-inch mandrel system with a X-pipe. DiFillipo cat
converters and a pair of large body mufflers are also squeezed under the
floorpan. Geoff is rapt in the exhaust system – it sounds great without being
On PowerTorque’s Dyno Dynamics chassis dyno, Geoff’s Senator has punched out
enough power to shame the majority of supercharged LS1s. This baby has run a
no-BS 501 horsepower (374kW) at the wheels on pump fuel and the full exhaust
system in place.
We think this Senator just moved up to world leader status!
So what sort of driveline is necessary to cope with an atmo engine as raunchy
Well, Geoff spent seven grand on tricking the standard 4-speed auto
transmission and installing a 3000 rpm stall converter (the engine starts to
come on song at 3000 rpm and continues to flex muscle to 7000 rpm). At the rear
is the standard differential and axle set-up with minor mods to improve strength
Geoff hasn’t had the chance to run an official quarter mile pass but an
‘unofficial attempt’ showed there is easy mid 10-second performance on tap.
Geoff says the car has also lined up against a proven 10.3-second car and
managed to nose ahead...
But all this performance comes with a civility not usually associated with a
Geoff has taken pains to ensure the standard Senator leather trim goes
untouched, noise levels are sane and the ride is comfortable. At present, the
car rides on an off-the-shelf coil and damper combo (which drops the ride height
about 2 ½-inches), but Geoff says he plans to switch to Bilsteins.
Braking confidence is enhanced by the installation of Alcon six-pot front
callipers and 383mm discs. The rear brakes remain standard HSV.
Visually, the HSV Senator body kit is sharply styled and eye-catching – no
need to change anything, except for the fitment of a genuine Holden Monaro
bonnet. The rolling stock has also been upgraded to hard-to-miss Lenso 20s.
At the time of writing, Geoff is nearing completion of this project. Aside
from changing the suspension, he has plans to install genuine C5R heads (costing
AUD$16,000!) and take a run at becoming the first atmo LS1-powered GM into the
We can’t think of another Senator with such incredible ambition.
PowerTorque +61 7 3881 2379