Cummins and Mercury Marine recently signed an agreement to supply a complete range of diesel sterndrives and inboards for the South Pacific region.

Known as Cummins MerCruiser Diesel (CMD), the 50/50 joint venture will also supply SmartCraft and other electronic hardware and displays from one of the best service and customer support networks in the region. Currently there are more than 600 Cummins and MerCruiser branches and dealers in the South Pacific.

What this means for boatbuilders and existing boatowners alike is that customers will be able to select from a range of diesels from 1.7-14lt displacement, along with a full installation and ongoing support infrastructure.

THE CUMMINS RANGE
Cummins offers a range of engines from 3.9-14lt and 80-525hp available in Continuous (tugs and displacement trawlers), Heavy and Medium Duty and Intermittent ratings. All models have closed circuit (heat exchanger) cooling systems for a long engine lifespan and reliability.

Typical of the smaller models is the 155B. This 3.9lt turbocharged four-cylinder engine develops a maximum of 153hp (114kW at 1.0hp = 746W) and Intermittent rating of 150hp, both at the crankshaft and at 2800rpm. In bobtail form (minus gearbox) it weighs 423kg and measures 780mm long, 704 wide and 771 high. According to Cummins, the average fuel consumption at 2500rpm is 21.2lt/h.

All other models up to 14lt are straight sixes. Models such as the 4B/4BT3.9M through to the 6BTA5.9M are available in both Medium Duty (76-225hp) and Intermittent ratings (150-315hp). The 6BTA5.9-M and electronically-managed QSM11-M are available only in Intermittent ratings from 350-580hp.

The 10.8lt QSM11-M was reviewed a few years ago in Trade-A-Boat and was designed specifically for gameboats and other fast recreational cruisers. It produces 2332Nm of torque at only 1700rpm and in bobtail form weighs 1122kg and measures 1293mm long, 978 wide and 978 high.

Reviewed in Trade-A-Boat about four years ago, the 14lt N14-M is the largest of the CMD engines on offer. It's available in three ratings: continuously-rated models (those suitable for tugs and displacement trawlers) provide 360-440hp, Heavy Duty models 480hp and Medium Duty 525hp.

The torque outputs range from 1836Nm at 1400rpm for continuous rating through to 1380 at 1500 for Medium Duty. In bobtail form the N14-M measures 1454 x 876 x 1262mm and weighs 1367kg.

THE MERCRUISER RANGE
MerCruiser diesel sterndrive and inboard models range from 1.7-7.3lt, the largest of these also being available in Ford F-Series trucks. To compare with the Cummins counterparts, all horsepower ratings following are at the crankshaft.

All models have closed circuit cooling and all models from D2.8L upwards have a 65amp 917W alternator. All sterndrive models from the D2.8L upwards are available with either Bravo One X, Bravo Two X or Bravo Three X (with counter-rotating props) legs. A choice of Primary, Optional and High Altitude gear ratios are offered in both sterndrive and inboard models.

D-Tronic models have an Electronic Control Module that monitors information from a strategically-placed sensor around the engine 50 times per second to vary fuel flow and injector spray timing according to engine revs, load and barometric pressure. The injectors are hydraulically-actuated and electronically-controlled to reduce fuel consumption and exhaust emissions.

Reviewed in Trade-A-Boat last year, the D1.7L DTI is available only with an Alpha leg and as a package weighs 296kg. Based on an Isuzu automotive diesel, it develops 120hp at 4200rpm from its 1.7lt DOHC four-cylinder direct injection powerhead. It has turbocharging and intercooling and develops a massive 264Nm of torque at only 2400rpm. The engine-only measurements are 748 x 746 x 689mm. A 50amp 600W alternator is standard.

In twin installations the D1.7L DTI has proven particularly successful in repowering older hulls such as the Bertram 25.

Next in the range is the D2.8L D-Tronic, available in both sterndrive and inboard versions. This four-cylinder 2.8lt turbo-intercooled engine has hydraulic valve lifters for low maintenance. The sterndrive model develops 165hp at 3700rpm, complete with Bravo Two X leg weighs 468kg and has engine-only measurements of 1241 x 762 x 766mm.

The inboard model develops the same power at the same revs and complete with a single speed ZF box weighs 461kg. The overall length is 1244mm and width and height dimensions the same as the sterndrive model.

A straight-six version of the 2.8lt model, the 4.2, is available in both indirect and direct injection models depending on customer requirements. Sterndrive models are available in three variants, the top of the line being a D-Tronic model that develops 250hp at 3700rpm. Complete with a Bravo Two X leg it weighs 584kg and measures 1170 x 760 x 767mm.

Other 4.2lt sterndrive models are the D4.2L, an indirect injection engine developing 220hp at 3500rpm and the direct injection D4.2L LD rated at Light Duty for patrol boats and search-and-rescue vessels, which develops 200hp at the same revs.

Only one inboard model is available, an indirect injection engine developing 220hp at 3500rpm, which weighs 528kg and measures 1473 x 711 x 533mm with a single speed ZF box.

The V-eight D7.3L is available in two sterndrive and two inboard versions and all have electronic fuel management.

The D7.3L LD Sterndrive is Light Duty-rated for patrol boats and earch-and-rescue vessels and develops 260hp at 3500rpm. Complete with a Bravo Two X leg this model weighs 756kg and the engine-only dimensions of 1193 x 863 x 826mm are compact for a V-eight diesel of this output.

The Light Duty-rated inboard version develops the same power at the same revs, weighs 704kg with a single speed ZF box and measures 1295 x 863 x 826mm.

The D7.3L D-Tronic Sterndrive and Inboard were designed for recreational applications and develop 300hp at 3700rpm. The weights and dimensions are the same as the LD models.

For more information on the complete CMD range, contact Jonathan Seddon at Mercury Marine on (03) 9791 5822.