If you take a program for what it is, it can be useful. I used an early (cheap) Dynomation program to prove out a cam theory and pressure wave tuning on then new local restrictor 2-barrel engines. While I did have published lift/flow figures for the heads and took the results as qualitative comparisons of “what if” scenarios, there was a lot to be learned about cam and exhaust length selection.F1_eng wrote:How do you expect the 1D simulation software to predict airflow through each component, which is essentialy what governs torque.
This is a problem with models that people set-up for a guess, they are more or less worthless. A decent model needs to have 1D-3D coupling where more complex flow situations would be solved in 3D. This is because orifices have different Cd at different air and therefore engine speeds.
Anyone that knows what they are doing with engine simulation does not correlate to power figures, correlation of most models is done to volumetric air flow. The simulation software also predicts frictional power loss which is very in depth, it is more or less a whole different model. This friction model also needs to be correlated from a motoring rig for it to be of any worth in predicting power loss.
Also the valvetrain dynamic simulation would need to be correlated for a decent model.
My point being that a quick model is worthless. Unless you know very basic stuff like discharge coefficients of orifices, any change you want to predic are worthless. For example, you want to predict optimal inlet cam timing but if you are slightly out on your Cd for an orifice, the flow behaviour will be wrong and all corresponding results are way off.
Having done my simplified study, when NASCAR when to restrictor plate engines I could see they were barking up the wrong tree by running 8000 RPMs the first season. And in fact with time their RPMs dropped some four figure increment.
It’s a matter of recognizing the limitations of the program and your input data while looking for relative results.