[Knuto]

Originally Posted by Cyco

Kunto, I can't help on the maths because while I think I understand what you are trying to model I'm not sure of what to expect.

Have you tried the Lotus freeware engine modelling tool?

Thanks for the link. I think I have tried it out before
I'm trying to get a deeper understanding of what goes on within the engine. So far I've learned a lot. I get a big understanding of what effect each parameter has on performance.

Decided to relax at home this evening. I worked a little more in Matlab on the engine analyzer. Fixed a lot of small problems. For the equations I asked about, I just put a couple of minuses here and there and now it works.

I tried to model an example from the book, similar to what I posted earlier. Its emptying of a 912cm^3 cylinder of 1.5 bar, by opening a sliding-plate valve for 0.008 s. The pipe is 5.9 m long. Attached are to plots. First shows pressure 0.3 m from the cylinder and the second shows pressure 3.3 m from the cylinder.

The book says that 86.6 % of mass is still in the cyl after the valve shuts. I got 0.5% more than that, but I'm getting closer.

EDIT: OK, after reviewing the maps of discharge coefficients wich I copied from the book, Im now within 0.039%. I think the code is good now. I will go on to modell a 2-valve single cylinder next