Volvo Penta's New 61 And 71 Series For Workboats Developed Using Advanced Computer Techniques

Volvo Penta's new 61 and 71 Series are two new designs developed with the aid of advanced computer techniques. These in-line six-cylinder marine diesels are direct injected, turbocharged and aftercooled and are said to give the boat operator outstanding performance, increased operational reliability, reduced exhaust emissions, and improved overall economy.

In order to give the engine block maximum rigidity without increasing the total weight, Volvo Penta has exploited the latest computer techniques (Finite Element Analysis), making it possible to significantly increase power outputs compared to previous 6- and 7-liter diesel engines.

The TAMD 61A and 71A have the following advanced features: new cylinder head with flame barrier that increases gasket life; new method for tightening the cylinder head bolts, each bolt having exactly the same torque for improved sealing; new cylinder head intake and exhaust channel design giving an identical swirl characteristic for each cylinder, reducing smoke and increasing fuel efficiency; front end mounted junction box for all electrical connections and relays, simplifying installation and service, particularly twin installations; new geardriven fresh-water circulation pump for higher efficiency and reduced noise and vibration; plate type oil cooler provides more effective cooling of the engine oil; adjustable rear engine brackets for easier installation; new adjustable anti-vibration mounts reduce vibrations transmitted to the hull and thereby reduce noise and increase comfort.

New technical developments have made it possible to achieve an extremely low weight/power ratio— 2.2 kg/hp for the TAMD 61A and 2.3 kg/hp for the TAMD 71A with the output set for light duty operation.

Increased power outputs have been possible through further developments of direct injection, turbocharging and aftercooling technology- The engines are fitted with oilcooled pistons that reduce the buildup of carbon deposits. In addition, there is a new type of thermostat and gear-driven fresh-water pump. These are some of the detailed improvements that contribute toward high operational reliability and long service life.

Air pre-heating means easier starting in extreme weather conditions and reduced exhaust smoke during the start-up phase. Furthermore there is a pressure regulator that allows the heated air from the turbocharger, at pressures below 0.3 bar, to bypass the aftercooler and pass directly into the intake manifold.

This leads to a cleaner exhaust at idle speed and low load operation.

The engines are also equipped with fuel injection pumps fitted with smoke limiters for reduction of black exhaust emissions during acceleration.

Simple installation and simple service are of utmost significance for overall economy and special emphasis has been placed on these aspects during the design phase of the new 61 and 71 Series. Some examples reflecting this are the cable harness from the instrument panel can be directly coupled to the engine's electrical components through the use of plug-in connectors; the seawater pump, oil filter and oil filler are placed for ease of accessibility at the front end of the engine.

Engine specifications are easily adapted for different boat types and applications thanks to the wide range of optional equipment such as heat exchanger or keel cooling systems, extra alternators, 12V or 24V electrical systems, extra power takeoffs, bilge and deckwash pumps, front end mounted oil filter and adjustable anti-vibration mounts.

The transmission program has been selected to suit varying boat types, from heavy displacement boats to light planing craft. The program ranges from the MG506 to the MG509 and also includes the new MG506A with a 10° down angle output shaft. A choice of reduction ratios are available from 1:1 to 4.95:1.

For free detailed literature fully describing the new 61 and 71 Series from Volvo Penta, Circle 69 on Reader Service Card

Maritime Reporter Magazine, page 10, Oct 1986

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Maritime Reporter

First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.