Combustion Pressure Sensor - revisited

[Dave Williams]

-> Duckworth lately??? :-) (Or just reading Glassman?) Only thing that I
-> would add is that I THINK that there is no such thing as TOO quick a
-> burn--so long as the patterns of turbulence in the chamber are
-> CONSISTENT. I think that the urban legend that too quick a burn leads
-> to a rough running engine

 GM discusses this in some of their engineering papers - the one for the
2.0 SOHC in the J-Car is a good example.  The 2.0 used a quick burn
chamber, offset ports, and swirl vanes in the ports to give a very high
amount of turbulence in the chamber.  Worked great for fuel economy and
emissions, but it took a lot of fiddling before the NVH guys would sign
off on it.  When the cars reached the dealers there were further
problems, not just with customer complaints, but with experienced GM
line mechanics diagnosing idle/low speed combustion noise as ping.  GM
wound up issuing a number of service bulletins on the subject.

 Note the fast burn posed no mechanical problems; the only problems were
in noise, vibration, and harshness, which are always troublesome for 2.0
sized fours to start with.

==dave.williams at chaos.lrk.ar.us======================================
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