[dkirk]

racing97 - thanks for your rapid reply. 38mm it is.

motogman - I used the Virtual Engine software when I worked for Mercury Marine. I'm now retired and need to keep my skills up, so I thought I'd model a 911 engine. Using a 3.2 L as an example as I own one. Virtual Engines is similar to other commercially available codes such as GT Power and Ricardo Wave. I like Virtual Engines as all the theory and equations used are totally spelled out in Professor Gordon Blair's book, "Design and Simulation of Four-Stroke Engines", available through SAE. The other two codes don't tell you what they're using in the calculations, and that bothers me.

This project will be quite involved, time-wise, so there will be no results for the immediate future. I will have to occasionally tap into the resources of this forum to obtain some technical information as I don't have a disassembled 911 engine that I can take measurements from. Once the model is created, it's relatively easy to change things such as cam timings, inlet and exhaust system lengths, compression ratios, etc., and run rpm sweeps to get power and torque curves, fuel consumption, and all the parameters normally acquired during a real dyno test. If the numerical model is constructed accurately, experience shows the results to be within 98% accuracy to the real engine, everywhere within the operational envelope. Should be fun and interesting.