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Making the business case for FiTS2

With the increase in fuel prices the shipping industry is driving for efficiency and savings, the FiTS2 sequential turbocharging system is an obvious and cost-effective choice for two-stroke engines.

FiTS2 – ABB’s solution for optimum fuel consumptions during slow steaming

When crude oil prices rose sharply, practices such as slow-steaming were introduced to reduce fuel costs, but propulsion systems were often not optimized for lower speeds. Standing for Flexible integrated Turbocharging System for two-stroke engines, this sequential turbocharging system offers significant fuel savings whilst maintaining flexibility in engine and vessel operation. Turbocharging efficiency is a critical factor in engine operation and ABB Turbocharging’s new FiTS2 solution promises to meet high efficiency targets. Developed with key engine designers, FiTS2 is available to all two-stroke engines.

Why FiTS2?

FiTS2 benefits include a high potential of lower engine fuel consumption by up to 6 gr/kWhr when operating at part or low load, but with flexibility of operation maintained up to full engine power. This is achieved by using automatic cut-out and cut-in of a selected turbocharger whilst the engine continues to run under load. Large two-stroke engines are also often fitted with auxiliary blowers but in many cases FiTS2 will be able to support slow steaming without these running. Auxiliary blower switch-on can typically be reduced from around 35 per cent engine load to 25 per cent, thus saving energy.

Major savings regardless of fuel prices

The system enables fuel savings of up to 6 grams per kWh (3 – 5 percent) compared with fuel consumption levels typically achievable with conventional turbocharging systems on low-speed diesel engines. Depending on the price of fuel and the load profile to be met by the engine, fuel savings over ten years can amount to 500,000 USD for a very large crude carrier (VLCC) and well over 1 million USD for a container vessel.

How does it work?


The typical engines for large tanker, bulkers, and feeder container vessels with conventional turbocharging systems run with 2 same-type turbochargers, which are always in operation in high loads, but as well in low engine loads. To optimize engine efficiency via improved turbocharging in low and part load, the engine with FiTS2 runs in lower loads with only one turbocharger in operation, whereas at higher loads (typically above 50 to 60 per cent engine load) two turbochargers are operating simultaneously. The same principle is applied for very large engines – with FiTS2, they will run with two turbochargers in lower loads and with all three turbochargers for higher load operation.

For large container vessels, which might use three turbochargers, one unit, can be adapted to shut off at lower power demands, typically below 50 per cent load. Engine settings are optimized as part of the FiTS2 design, and the system can be returned automatically and rapidly to its original full power capabilities. High load performance is therefore available combined with enhanced efficiency performance at lower loads. As illustrated, many large vessels can spend 50 per cent or more of their operating hours at below 50 per cent engine load. FiTS2 savings at these lower loads are significant.