3.2 Cylinder Head Info

[dkirk]

Would one of you kind individuals with Porsche engine experience please let me know the exhaust port diameter in the 3.2L cylinder head? Please measure port diameter at the point where the exhaust header tube mates with the port in the head casting.

I'm trying to put together a digital model of the 3.2 engine using Optimum Power software, a full computer simulation of a 4-stroke, multi-cylinder engine. The program tracks all pressure waves in the inlet and exhaust system which ultimately are critical in predicting the performance of the "virtual" engine throughout the operational rpm envelope. Should be interesting to compare model results to actual dyno data.

[motogman]

Very cool project. I am sure someone here will have the port dimensions- I am not sure if those are in Wayne's book or not.

How into the CFD world does this simulation software go? Can is show the impact of cam geometry on low end / high end performance or the impact of port size? How about port surface finish etc. I look forward to seeing some of the output.

[racing97]

84/89 3.2 Carrera part no. 930 104 033 02 38mm exhaust port

[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.

[dkirk]

Here's a link to the Optimum Power website for those interested:

OPTIMUM Power Technology - Virtual Engines

[targa72e]

hear is information I have on stock 3.2 head flows (and CMW) if that helps.




john

[dkirk]

John, thanks very much for the 3.2 engine airflow data. very useful for comparison once I have the model up and running.

I'm going to start a new thread entitled "Computer Modeling of the 3.2 Liter 911 Engine" as it better describes my motives. I may be asking individuals for input that have experience and knowledge of the 911 engine. Hopefully this will be beneficial to all that are interested. Once the model is constructed, debugged and running, it will be easy to look at changes in exhaust and inlet systems, cam timings, and engine displacements. Steve Wong's website has lots of dyno data on the 3.2 engine and this will be an excellent resource for performance comparisons.