An online magazine dedicated to the lifestyle and challenges
of professional towboating.
Towboat of the Month
Tips & Tricks
Pilot Database
Who Are We?
Contact us.

February 2006
Article Archives:
Most powerful diesel engine in the world
If the Seven Wonders of the World was updated for
the 21 st century, the Wartsila-Sulzer RTA96-C
turbocharged two-stroke diesel engine could be a
contender. If you are a student of the internal
combustion engine in all its wonderous
configurations, then feast your eyes on this set of
numbers which outline the truly astounding
engineering feat. It is the most powerful and most
efficient engine in the world today.
Designed to provide the motive force for a variety of
supertankers and container ships, it comes in 6 cylinder
in-line through to a whopping 14 cylinder version. The
cylinder bore is 38 inches and the stroke is just over 98
inches. Each cylinder displaces 111,143 cubic inches
(1820 litres) and produces 7780 horsepower. Total
displacement comes out to 1,556,002 cubic inches
(25,480 litres) for the 14-cylinder version.

At a length of 89 feet and a height of 44 feet, the total
engine weight is 2300 tons - the crankshaft alone
weighs 300 tons.

The RTA96C-14 can achieve a maximum power output
of 108,920 hp at 102 rpm and astonishingly, at
maximum economy the engine exceeds 50% thermal
efficiency. That means, more than 50% of the energy in
the fuel is converted to motion. Its Brake Specific Fuel
Consumption (BSFC) at maximum power is 0.278

Ship owners like a single engine/single propeller design
and the new generation of larger container ships
needed a bigger engine to propel them.While engine
cylinder configurations for large-scale container liners
have been discussed in the magnitude of 14, 16 and 18
cylinders, the 14-cylinder in-line low-speed engine is the
first to be offered by any engine designer.

Ship owners prefer single engine/single propeller
designs and the new generation of larger container
ships (or post-Panamax) called for a bigger engine to
propel them.

The RTA96C-14 turbocharged two-stroke diesel engine
is produced by Swiss company Wartsila-Sulzer and is
the largest and most powerful diesel engine in the world

The peak capabilities of the 14-cylinder RTA96C engine
now exceed 80 MW, making it adequate for a
single-screw Post-Panamax container liner, which is as
large as container liners will get considering their
greater cost-effectiveness.

Sulzer have also managed to increase cylinder output
since they began first operation in 1997, due to the
maintenance experience accumulated with the large
number of RTA96C engines currently in service. The
new kW rating of the new engine achieves a power
output of 68,640 kW, a four percent increase on the
initial RTA96C.

Despite the large amounts of power produced by these
engines, surprisingly low wear rates have been
achieved. Diametral cylinder liner wear is in the order of
only about 0.03 mm/1000 hours.

This low cylinder wear is possibly attributed to a
connecting rod that attaches to a "crosshead" which
rides in guide channels, a fundamental difference to
most automotive engines where the top of the
connecting rod is attached directly to the piston.
Instead, in this engine the top of the connecting rod
attaches to a "crosshead" and a long piston rod then
connects the crosshead to the piston. This lowers the
sideways forces produced by the connecting rod and is
absorbed by the crosshead and not by the piston.
Sideways forces are what makes the cylinders in an
auto engine become oval-shaped over time.

Fuel consumption at maximum economy is 0.260
lbs/hp/hour. Comparatively, most automotive and small
aircraft engines can only achieve BSFC figures in the
0.40-0.60 lbs/hp/hr range and 25-30% thermal
efficiency range.

The design and development of the RTA96C was close
collaboration with the companies involved in the early
stages of the first commercial project: the owner and
operator P&O Nedlloyd BV, the ship designer and
builder Ishikawajima Harima Heavy Industries Co Ltd
(IHI), and the enginebuilder Diesel United Ltd.

The project began in March 1997 when the first engine,
an 11-cylinder unit, was started on the test bed of
Diesel United Ltd, Aioi.

Since then a total of 86 RT96C engines with eight, nine,
ten, 11 and 12 cylinders in-line are in service or on
order, 25 of these currently in service.
To submit articles about piloting, navigating, towbuilding or anything  
regarding life on a towboat please email:
An online magazine dedicated to the lifestyle and challenges
of professional towboating.