[Knuto]

Havnt done much lately.

I just started working on an engine analyzer. I want to model pressure in the engine piping and calculate thermodynamic and gas properties in the entire engine. Ive read the book Design and Simulation of Four Stroke Engines by Gordon P. Blair, which I now call the bible. Amazon.com: Design and Simulation of Four Stroke Engines [R-186]: Gordon P. Blair: Books

I have a problem solving one problem though. I have 4 nonlinear equations I need to solve for 4 unknowns. I get good result through Newtons method if make a good first guess, but it quickly goes bananas. Any mathematics around who can help??

Ive started modelling outflow from a constant volume cylinder. I attached a plot from the result so far. It shows the pressure ratio (p/p0) for cylinder/plenum as a function of time. Also shows leftward wave (going towards the plenum) and rightward wave (going towards the pipe end) and the superposition pressure of these at a certain point along the pipe. It is wrong in assuming that the pressure at the throat of the pipe is equal to the cylinder, so the cylinder emptys to fast. I need to solve the 4 equations to get the pressure ratio at the throat. But the good thing is that pressure waves dynamics in the pipe is correct.

Cyco, modelling your V12 performance will be my big aim. But its gonna take some time...

EDIT: After working a little bit i think the problem is the equations. I think one of them might be wrong. the method seems ok