With a brake mean effective pressure of 2.45 MPa, a mean piston speed of 10 m/s, and a power-rate of 24.5 MPa-m/s, these engines represent the acme of marine engine technology. Engine output covers the range from 1392 to 9990 kW. (Fig.1)  As the example of the new medium-speed diesel engine series, the general view of V22HLX is shown in figure 2
3. DEVELOPMENT POINT OF VIEW
The following requirements must be satisfied when resource conservation, energy efficiency, and reduced environmental impact are regarded essential conditions in marine engine development:
1. Compact size and high engine output
2. High efficiency
3. Reduced NOx level
4. Reduced the life cycle cost (in terms of equipment, operating, and maintenance costs)
In designing this new medium-speed engine series, we attempted design optimization by conducting exhaustive analysis and structural analysis based on a database of past unfit designs, on simulations, and on component tests to avoid increased cost resulting from proportional designs, all while aiming at a drastic increase in output by at least 30% compared with conventional models, and also by maintaining a high reliability.
Furthermore, targets were set up for the prime costs of engines to be developed and for engine performance, while taking a concurrent engineering approach to permit cooperative work by relevant departments, concurrently and in parallel mode. As a result, development time was reduced by 15%, the number of parts involved was reduced by 30%, compared with conventional models, and the reliability and cost minimization goals were met. The developed product thus successfully responds to market needs.
Specifically, the engineering approach brought about an improvement in power factor by use of a smaller cylinder diameter with longer stroke, improved cycle efficiency by increasing the compression ratio, optimized explosion rate, reduced initial cost by cutting various costs, reduced lubricating oil consumption, and prolonged maintenance interval.