| Vessel Make: | Carver Voyager 37 |
|---|---|
| Old Engine: | Cummins 6BTA |
| New Engine: | FPT NEF 400 |
| Old Engine Power: | 315Hp @ 2,800rpm |
| New Engine Power: | 400HP @ 3,000rpm |
| Cruise Speed: | 22kn @ 2,400rpm |
| Max Speed: | 30kn @ 3,000rpm |
Cummins 6BTA Rebuild ? Not worth it!
An American-made Carver Voyager 37 vessel here in Perth previously had 2 Cummins 6BTA marine engines, where one engine seized up, leaving the owner facing a big decision: rebuild the old engine or repower with something newer, more reliable, and future-proof?
Saltwater had entered the pistons of one of the Cummins 6BTAs, causing the engine to seize. Rebuilding would’ve meant stripping it back to the bare block, inspecting for internal corrosion, replacing outdated parts, and investing serious time and labour. Is it worth trying to get a Rebuilt Cummins 6BT ? Definitely not – all with no warranty at the end. Not to mention the older mechanical technology still in the mix, the financial and practical value just didn’t stack up.
The Repower Solution
Instead, the smarter option was to repower the vessel with two new FPT NEF 400 marine engines – a reliable, high-performance solution that delivers long-term benefits without the headaches.
The original Cummins 6BTA marine engines were rated at 315Hp at 2,800rpm. The FPT NEF 400s provide the same output and more – capable of 400HP at 3,000rpm. However, in this repower, we electronically derated them to 370HP at 3,000rpm to match the existing shaft and gearbox capabilities.
Ease of Integration
One of the standout advantages of switching to FPT was how seamless the transition was from Cummins:
- The FPT NEF 400 has the exact same 5.9L displacement as the Cummins 6BTA.
- The turbo outlet flange matched perfectly, so the existing exhaust system bolted straight off the old engine and onto the new engines.
- The gearbox bellhousing matched too – meaning no need to modify shafts or gearboxes.
- With smaller engine dimensions, particularly in width, access around the engine is now far easier for future servicing and inspections.
Smart Displays and Diagnostics
To complete the setup, we installed two 5-inch digital touch screen panels that offer real-time RPM, engines data, diagnostics, fuel consumption info, and more giving the skipper clear oversight of performance at all times.
Performance on the Water
At sea trial, the Carver Voyager 37 achieved 22 knots cruising at 2,400rpm, and a top speed of 30 knots at 3,000rpm – a remarkable result that exceeded expectations.
Fuel efficiency was another win. The FPT’s Bosch common rail electronic fuel injection system is not only more advanced than the old mechanical setup but also much more fuel-efficient. The result? Lower fuel burn, no black smoke, and quieter, smoother operation.
Modernised Controls – New Flexball Throttle Control System
Beyond the engine bay, the repower also included a full control system upgrade. Previously, the Carver used two separate throttle levers – one for throttle, one for gears – requiring two-handed operation.
We replaced that with a Flexball electronic throttle system, simplifying everything into a single twin-lever control. It now handles both throttle and gears seamlessly and is electronically synced to allow for twin-engine control when needed.
