First test bed results

The following results were achieved with the very first prototype on the Ilmor Ltd. test bed, without the opportunity for any complex optimisation. In fact these results were achieved within the first two months after the engine was fired up for the first time. Afterwards Ilmor Ltd. did undertake further optimisations, but did not communicate the results. It is obvious that a period of further intensive development of the 5-stroke engine would result in significant improvements. The most important measurement results are summarised below.
This complete interim report is available here in English as a PDF file.

Figure 1. Measured specific fuel consumption

Figure 2 shows that the higher rpms do not give rise to any problems for the 5-stroke engine. The losses associated with flow transfer from the high-pressure cylinders to the low-pressure cylinder are much less than originally feared.

Figure 3. Measured charge pressure and temperature

Figure 4 demonstrates an extremely interesting feature of the 5-stroke engine. In spite of a charge pressure of almost 3 bar the exhaust gas temperature at entry to the turbine does not reach the critical 850°C limit. This means that variable turbine geometry technology can be deployed in the 5-stroke engine without any further modifications, as a result of which both response characteristics and fuel consumption can be further optimised.

Figure 5. Brake specific fuel consumption at part load

Figure 1 illustrates the “flat” profile of the measured specific fuel consumption as a function of increasing rpm at full load. This is a special feature of the 5-stroke engine, which can be attributed to a combination of the low compression ratio of the high-pressure fired cylinders and the second-stage expansion.

Figure 2. Measured power output data

The measured charge pressure illustrated on Figure 3 of nearly 3 bar absolute was achieved with a conventional Garrett turbocharger, with no special tuning to the prototype.

Figure 4. Measured exhaust gas temperatures

Figure 5 contrasts the brake specific fuel consumption (BSFC) measured on the 5-stroke prototype with that of a conventional Otto-cycle engine (Saturn 1.9 litres) at a number of operating points in the part load range. At the present time unfortunately only a very incomplete set of measurements is available for the part load range.