RAETECH engineers work extensively with our technical partners at Optimum Power Technology to develop and apply state-of-the-art computer analysis to engine development. Optimum Power's Virtual 4-Stroke is a 1-D, unsteady gas flow based, four-stroke engine modeling system. Engine configurations that can be designed include all single and multi-cylinder layouts, spark and compression ignition, and both carbureted and fuel injected. Complex manifold arrangements can be designed and optimized including active intake manifolds and tuned exhaust systems that maximize the benefits of cylinder interaction.
The simulation results displayed on the right is for a normally aspirated, four cylinder, sixteen valve, road racing engine. Performance variations due to inlet runner geometry are explored within the normal operating range of the motor.
This plot is the output from an intake runner length (x-axis) and diameter (y-axis) sweep . The z-axis surface height represents the performance of that combination of length and diameter relative to a baseline value of 1. Values below 1 mean an improvement Ė more power Ė while values above 1 are worse than the baseline. On this engine, itís clear you donít want a small diameter runner with a length of about 300mm.
While this plot gives a definite result in that there is a best combination, the left-to-right ridges indicate that at particular runner lengths, the diameter isnít too important. This on its own is an encouraging finding because itís usually much easier to change a runnerís length (with spacers, say) than it is to change diameter. Another worthwhile finding is the relatively flat nature of the result surface, showing that the optimum solution is in a benign region, not critically dependent on precise length or diameter values.
Intake runner dimensions are just one aspect of the truly comprehensive range of engine parameters and their relationships RAETECH can model with Optimum software. Parameter studies can save a tremendous amount of time and money by efficiently identifying areas of an engine program most likely to yield results.