Trade-A-Boat — 490 2017

quickspecs

Nannidiesel 6.420 TDI

ENGINE TYPETurbo-

intercooled direct injection

straight six

RATED BHP/MHP*

315.7/320.2 at 3600rpm

MAX TORQUE795nm at

2400rpm

DISPLACEMENT4163cc

BOREXSTROKE94x100

mm

WEIGHT469kg (dry, with

ZF63A ’box)

*Brake horsepower/metric

horsepower

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sea trials

Because this engine has mechanical fuel injection it shouldn’t be operated continuously

below 2000rpm or above 3300rpm. The fuel flow figures below are for displacement and

semi-displacement hulls and the engine may use slightly more fuel under load during

transition from displacement to planing mode.

RPM NM BHP ABSORBED BY PROP ACTUAL L/H

1200 460 5 3

1600 490 9 6

2000 725 30 14

2400 795 80 25

2800 765 145 33

3200 700 225 46

3600 630 315 60

Note the rapid torque rise from 1200 to 2000rpm and how much torque is still available at

3600rpm.

Mono grades don’t thicken
as engine temperature
increases but in a cold snap
may create starting issues.

ON THE WATER
Although I haven’t tried
the 6.420 TDI in a boat I did
test twin Yanmar versions
in a mate’s Cresta 32. The
twins started instantly with
low vibration levels and
blew black smoke from fuel
oversupply only when the
hull was coming out of the
hole. Unusually, the engines
are mounted aft-facing and
swing four-bladed 19x21in
props via ZF63IV V-drives
with 2:1 reductions.
Pushing a 7.8 tonne
displacement the Yanmars
returned an offshore troll
of 9.1kt and 1500rpm using
6.0L/h each.
As with all correctly
matched hulls and engines
the Cresta planed at less

than peak torque – in this

case 14.0kt and 2200rpm.

Fully planing at 17.7kt and

2500rpm the engines were

at peak torque and returned

an excellent 19.5L/h each.

Increasing to 3500rpm

(maximum continuous rpm)

the Cresta averaged 26.7kt

using 41.0L/h each. The

wide-open throttle averages

were 29.4kt and 3800rpm

using 60.0L/h each, and we

could still talk normally.

With the increased torque

6.420 TDI this hull should

plane at lower rpm, deliver

better cruising economy and

maybe crack 30kt!

THE WRAP

Nannidiesel is smart to use

the Toyota base. The 4.2L

unit, along with its 3.0L

four-cylinder counterpart,

are among the smoothest-

running and most reliable

automotive diesels ever

and it’s comforting to know

many parts can be sourced

from Toyota dealers.

See nannidiesel.com.au.

The boat you want is easier to find tradeboats.com.au^73