Need Help With Volume Calculations

[mihalkog]

I'm doing some compression ratio calculations and need certain piston and cylinder head related measurements, but have been unsuccessful in finding a source. Does anyone here know the following dimensions or a place where I can look them up?

1. CYLINDER HEAD VOLUME FOR 2.4S
2. PISTON DOME VOLUME FOR 2.4S OEM MAHLE PISTON
3. PISTON DOME VOLUME FOR 2.2E OEM MAHLE PISTON

Thanks in advance for any help.

[mihalkog]

Where have all the GURUs gone? Where are they now? The answer my friends is blowing around here somewhere - I hope.

[Flieger]

Bruce Anderson says in his Porsche 911 Performance Handbook, 2nd edition, that all 2.2-2.7 (1970-1977) cylinder heads have combustion chamber volumes "in the range of 68cc", only the valve sizes varied.

[edmayo]

George, I have actual volume numbers that you are asking for, just forgot to bring them home tonight, I'll try to do better tomorrow!

[mihalkog]

Thank you Guru Max & Guru Ed.

[edmayo]

Hi George, found half of what you wanted, I have the specs from one of my engines, a 2.4 S , hope this helps. Cylinder head volume ranged from 67 to 67.6cc's. Piston dome volume ranged from 15.6 to 16.2 cc's. This the installed P.D.V. that is it is measured with the piston installed so that it also takes into account the deck height volume. Combining the largest C.H.V. with the largest P.D.V. and working thru the rest until at the end you have the smallest C.H.V. with the smallest P.D.V. you get a compression ratio range of 8.59 to 8.53. I couldn't quickly find any 2.2 similar info.

[mihalkog]

Thanks Ed. I'll send you an email regarding what I'm contemplating doing to my 2.4S engine.