The authors started from the observation that by increasing the fuel injection pressure it is possible to increase the engine power density while maintaining the engine peak
firing pressure (pfp) constant.
Peak
Firing Pressure (PFP) prediction of the model was well aligned with the test data at entire engine operating range.
If it won't work right on the bench with dummy rounds, adding 45,000 psi of
firing pressure to the equation is not going to make things work better.
"The
firing pressure in the combustion chamber causes the rings to load from the back side pushing out against the cylinder wall.
"The
firing pressure in the combustion chamber causes the rings to load from the back side, pushing out against the cylinder wall.
Increased
firing pressure might have been one of the factors contributing to the accounting shenanigans of the late 1990s.
A thorough comparison has been initially carried out between the SP and the MP mode using the experimental readings from the steady engine map (Figure 2) in terms of torque, the average peak
firing pressure (PFP), brake specific fuel consumption (bsfc) as well as turbine inlet temperature.
Other significant improvements included lowering of the turbo speed by 400 rpm (resulting in longer turbo life cycles) and a drop in peak cylinder
firing pressure by as much as 90 psi (for longer power pack life).
Eventually, even the peak
firing pressure (pfp) was constrained to a relatively 'common' value of 200bar on recent engines, in order to avoid compromising too much the engine design for keeping the mechanical efficiency at part load on a high level [6].
"It used to be that the peak
firing pressure on a diesel was 150 bar, and it's now 175 bar," he says.