torquing
talk
WITH ANDREW NORTONGoing Straight
FEW ENGINES BALANCE LIKE A STRAIGHT SIX
I
n recreational boating,
where more V-block
automotive diesels
are being marinised,
it’s refreshing to
encounter an inline engine
in the 4.2-litre range. Inline
engines offer better service
access, particularly twin
installations where V-blocks
can put the inner cylinder
banks close together.
Sure, an inline engine will
never have that wonderful
V rumble, but being the
practical nerd I am, I’d go for
servicing ease.
Nannidiesel’s turbo-
intercooled 6.420 TDI is one
inline engine that not only
offers servicing simplicity
but also a proven record of
reliability as it’s a marinised
Toyota Landcruiser 100
engine. A straight six with
SOHC and 24 valves, it’s
an interference engine but
providing the camshaftbelt is checked annually
and replaced every 800 to
1000 running hours there
shouldn’t be an issue.THE NITTY GRITTY
The cast-iron Toyota engine
is unusual for a straight
six, having two harmonic
balancing shafts. Also
marinised by Yanmar,
Nannidiesel has extracted
more torque and power
from the same base engine
without electronic engine
management. Maximum
torque is up 14 per cent at
the same revs with peak
output two per cent higher
and 200rpm lower. With a
standard hydraulic gearbox,
weight is up four per cent.
Having direct injection
the compression ratio is
a relatively low 15.7:1, but
despite being mechanically
controlled the engine
complies with all currentEuro and US exhaust
emission controls.
Unlike many automotive
motors, the standard 80-
amp (120A optional) voltage-
regulated alternator is
mounted well above engine
bearer height, as is the
starter motor. The cam belt
is protected by a full shroud.
Heat exchanger cooling
with an engine oil cooler is
standard and the fuel/water
sedimenter is at the forward
end where it’s accessible.
The 6.420 TDI is available
with six hydraulic gearbox
options; the ZF63A is
standard. This ’box has an
eight-degree down angle at
the output flange; combined
with the maximum static
engine installation angle of
seven degrees, this means
the engine can easily cope
with a normal planing
hull’s shaft angle of around
12 degrees. The optionalZF63IV V-drive gearbox has
a 12-degree down angle so
in these installations the
engine can be mounted
parallel to the waterline.
Complete with ZF63A
the conventional shaft-
drive model is 1311mm
long, 669mm wide and
740mm tall. The standard C3
instrument panel includes
an analogue tachometer
with digital hour meter,
oil pressure and coolant
temperature gauges, a
voltmeter and alarms for
low oil pressure and high
coolant temperature.
A diesel-specific SAE
10W30 oil can be used in
colder climates and an
SAE 15W40 oil in tropical
conditions. If the engine
is likely to be worked
hard between oil and filter
changes in a temperate
climate a straight mono-
grade SAE 30 can be used.72 tradeaboat.com.au