Best Diesel Marine Engines

If you're looking to buy a new marine diesel engine you've come to the right place. We know budget might be at the top of your list of concerns, but we also understand the importance of finding the most reliable marine diesel engines to pick from. Here is our list of some of the best marine diesel engines from top manufacturers.

Caterpillar has started delivering its new C8.7, an in-line six-cylinder package that replaces the C9. With a new common-rail fuel-injection system and air system, the C8.7 produces 650 hp at 2,300 rpm, and it weighs 2,295 pounds dry. The new fuel system uses a radial belt-driven supercharger along with standard turbochargers to get the boat up to speed without lagging prior to the turbocharger engaging. Once up to speed, the turbo takes over to provide boost, and an electromagnetic clutch disengages the supercharger.

This redesign eliminates smoke and offers notable low-end torque and fuel economy while being EPA Tier 3 compliant. Obviously well suited to conventional drives, the C8.7 is also meant to pair up seamlessly to the recently introduced Caterpillar pod propulsion systems. The C8.7 is also compatible with existing CAT controls and displays.

Specifications
Horsepower: 650
RPM: 2300
Dry Weight (lbs): 2295
Displacement: 531 cu in / 8.7 liters

Specifications
Horsepower: 850 or 1000
RPM: 2300
Dry Weight (lbs): 3523
Displacement: 786.9 cu in / 12.9 liters

Specifications
Horsepower: 1150
RPM: 2300
Dry Weight (lbs): 4000
Displacement: 1106 cu in / 18.1 liters

Specifications
Horsepower: 1925
RPM: 2300
Dry Weight (lbs): 7155
Displacement: 1959 cu in / 32.1 liters

The new Cummins Quantum Series QSB 6.7 at 550 hp is the most popular output for this block in the recreational sport-fishing market. Based on an in-line six-cylinder block with a new 24-valve cylinder head, the folks at Cummins have also focused on noise and have netted an 80 percent reduction at idle from engineering changes in their high-pressure common-rail fuel system. This also plays a huge part in the elimination of smoke. Walker AirSep air filters now come standard and are also engineered to reduce noise at the air intake to the turbos. With a dry weight of 1,450 pounds, the QSB 6.7 is a Tier 3 compliant power plant able to fit many applications.

Specifications
Horsepower: 550
RPM: 3300
Dry Weight (lbs): 1450
Displacement: 408.1 cu in / 6.7 liters

Specifications*
Horsepower: 600
RPM: 3000
Dry Weight (lbs): 1975
Displacement: 505 cu in / 8.3 liters

Specifications
Horsepower: 410
RPM: 2100
Dry Weight (lbs): 2000
Displacement: 542 cu in / 8.9 liters

Specifications
Horsepower: 715
RPM: 2500
Dry Weight (lbs): 2620
Displacement: 661 cu in / 10.8 liters

With the need for compact, space-saving engines, boatbuilders and refit specialists alike have welcomed new slim in-line six-cylinder engines from MAN, with horsepower outputs of 730 hp and 800 hp at 2,300 rpm. With a common-rail fuel system producing power for maximum torque in the 1,200‑rpm range, the R6-730 offers 730 hp for rapid acceleration from low revolutions per minute engine speeds. At roughly 2,870 pounds, the R6‑730 offers a compelling horsepower-to-weight ratio for re-powers and new builds alike. Through proven optimization of the internal combustion system, the R6-730 does not need an external after treatment system to achieve Tier 3 emission compliance.

Specifications
Horsepower: 730 or 800
RPM: 2300
Dry Weight (lbs): 2870
Displacement: 786 cu in / 12.8 liters

Specifications
Horsepower: 1000 or 1200
RPM: 2300
Dry Weight (lbs): 4133
Displacement: 989 cu in / 16.2 liters

Specifications
Horsepower: 1400 or 1550
RPM: 2300
Dry Weight: 5004
Displacement: 1476 cu in / 24.2liter

Specifications
Horsepower: 1650 or 1800
RPM: 2300
Dry Weight (lbs): 5213
Displacement: 1476 cu in / 24.2 liters

The new 16V 2000 M96 from MTU has also started delivering, and our guess is we will be seeing a lot of these in larger sport-fishing packages. A 16-cylinder V engine producing 2,600 hp at 2,300 rpm, the M96 features a new fuel-injection system, in addition to three sequential turbochargers for better acceleration and fuel economy. The company’s SCR in-engine exhaust-gas treatment reduces emissions and makes the M96 EPA and IMO Tier 3 compliant. Electronically controlled, the M96 is a smokeless, quiet power package with reduced vibration. With the recent launch of the 92 Viking, performance characteristics of the 2,600 hp M96 are certainly noteworthy, with the enclosed bridge model reaching a top-end speed of 36 knots.

Specifications
Horsepower: 2600
RPM: 2300
Dry weight: 7474
Displacement: 2179 cu in / 35.7 liters

MTU also has a 12V 2000 M96 option that meets Tier 3 standards.

With 900 hp packed into it, the Volvo D13-900 is an in-line six that can be used as a conventional drive package or in conjunction with an IPS pod-drive power plant as we have seen for larger sport-fishing boat applications. With over 17,000 IPS systems on the water, Volvo has undeniably made an impact in the marine market with this technology. Weighing in at 3,439 pounds, the D-13 features a robust block with ladder-frame construction, high-pressure unit injection and twin turbochargers combined with charge-air coolers. Engine management from Volvo’s electronic control system combines low fuel consumption and emissions with reduced vibration and noise, and it exceeds Tier 3 standards.

Specifications
Horsepower: 900
RPM: 2300
Dry Weight(lbs): 3439
Displacement: 780 cu in / 12.8 liters

Specifications
Horsepower: 435
RPM: 3500
Dry Weight: 1620
Displacement: 336 cu in / 5.5 liters

Specifications
Horsepower: 700
RPM: 2300
Dry Weight (lbs): 3523
Displacement: 786.9 cu / 12.9 liters