Posted by jack cain from 209.86.131.117 (user-38ld0rl.dialup.mindspring.com) on Wednesday, March 20, 2002 at 10:12PM :
In Reply to: Dynamic compression ratio...pinging posted by George from 68.80.0.8 (cas02.toresd01.pa.comcast.net) on Wednesday, March 20, 2002 at 9:47AM :
I have actually given serious thought to building a system that would record the combustion chamber pressure and the rpm as well as the manifold pressure.
These systems are available commercially but the least expensive is several thousand dollars.
I believe I could do a "home-brew" system for significantly less - maybe several hundred dollars. I have located sources for a pressure transducer that would work extremely well in this application. As for recording the RPM and manifold pressure a crank angle sensor and a MAP sensor (scavanged from a big three vehicle) would suffice. The only remaining item would be an ACCEL or similar unit for varying the iginition timing across the RPM range.
The major problem that I have is signal conditioning and programming. Sure wish I had stayed awake in the class on data accquistion.