Bluefin HT700 Repower – Suzuki DF200TX V6

This Bluefin HT700 repower delivers impressive performance, improved fuel economy and renewed reliability

An Intermittent Fault Leads to a Repower

The owner of this Bluefin HT700 had been experiencing an intermittent misfire with its Mercury 200 EFI two-stroke outboard. Despite taking the boat to two separate marine workshops, neither had been able to identify the cause of the problem. With the fault remaining unresolved, the owner was ready to consider replacing the engine altogether.

During a visit to the NZ Boat, Fish & Dive Expo at Mystery Creek, the owner stopped by the Marine Power Systems stand to discuss his options. Following a conversation about the Suzuki outboard range and the benefits of modern four-stroke technology, the decision was made to repower the Bluefin.

Choosing the Right Suzuki – Four-Cylinder or V6?

Our initial recommendation was the Suzuki DF200APX, a modern 2.9-litre four-cylinder outboard equipped with Suzuki's Lean Burn Control System and electronic fly-by-wire throttle and shift. This engine offers excellent fuel efficiency and smooth operation, making it a strong contender for a boat of this size.

However, the owner had his sights set on the Suzuki DF200TX, a larger-displacement 3.6-litre V6 with traditional mechanical controls. His reasoning was simple: he wanted the strong torque and effortless power delivery of the bigger engine. As the old saying goes, "There's no replacement for displacement."

Although the V6 doesn't offer quite the same fuel efficiency as the four-cylinder DF200APX, it remains an economical performer, especially compared with the original Mercury two-stroke. The owner also recognised that either Suzuki would represent a substantial improvement over the ageing EFI.

Installing the New Suzuki DF200TX

With the engine selected, our technicians removed the Mercury 200 EFI and prepared the Bluefin for its new Suzuki V6.

The installation included new mechanical throttle and shift controls, replacement control cables and a Suzuki SMG4 multifunction gauge, giving the owner access to accurate digital engine information, including real-time fuel consumption. The existing hydraulic steering system was retained, as it remained suitable for the new engine.

The original dashboard also needed some attention. With the new SMG4 replacing several older instruments, we enlisted Kopu Marine to fill the redundant gauge openings. The owner is arranging for the dashboard to be reupholstered, which will complete the updated helm layout.

Sea-Trial Results – Impressive Performance From the V6

Following installation, we took the Bluefin HT700 out for sea trials to assess the new engine's performance and fuel consumption.

The results demonstrated just how well the large-displacement Suzuki V6 suits this boat. With its strong torque and responsive power delivery, the DF200TX pushed the Bluefin to a top speed of 37 knots at 5,400 RPM.

More importantly, the engine delivered excellent fuel economy at normal cruising speeds, recording just 21.8 litres per hour at 20 knots and 27.6 litres per hour at 25 knots.

Suzuki DF200TX – Performance Results

Finding the Cruising Sweet Spot

One of the most impressive aspects of these results is the engine's efficiency throughout the normal cruising range.

At 3,000 RPM, the Bluefin cruises comfortably at 20 knots while consuming just 1.09 litres per nautical mile. Increasing to 3,500 RPM brings the speed up to 25 knots, with virtually no change in fuel consumed per nautical mile.

Even at 4,000 RPM, the boat achieves an impressive 29 knots at only 1.18 L/NM. This provides the owner with a useful range of cruising speeds without a significant fuel economy penalty.

Naturally, fuel consumption increases at higher engine speeds, but with 37 knots available at wide-open throttle, there's plenty of performance in reserve when required.

A New Lease of Life for the Bluefin HT700

This repower has transformed the Bluefin HT700 from a boat with an unpredictable engine fault into one powered by a modern, reliable Suzuki four-stroke.

The new DF200TX delivers the strong performance the owner was looking for, while offering significantly improved fuel efficiency, quieter operation and the peace of mind that comes with a brand-new engine backed by Suzuki's seven-year recreational warranty.

While our original recommendation was the four-cylinder DF200APX, this project highlights the importance of choosing an engine that suits both the vessel and the owner's preferences. For this particular Bluefin, the appeal of the large-displacement V6 was hard to beat.

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