Brain Pharte

[Robert Harris]

Once upon a time, back when Moby Dick was a minnow, I used to work at a
chemical plant.   We used strain cells about 2" square or less to weigh bins
contained 50,000 lbs of product or more very accurately and this was well
before digital enlightenment by Bill Gates.

Many cylinder temperature gauges are simply sandwiched between plug and head.

Connect the dots.  Sandwich a strain gauge between the head and the plug in a
washer.   Shouldn't I be able to read the pressure just like I read the
weight.  The bin probably distorted the gauge less than the slack between
threads would allow the plug to move.  

Torque the plug down till it "reads" say 2000 psi.  Then as the cylinder
pressure builds, the pressure gets "less" as the plug moves away from the
head.  Invert the readings and voila - non invasive combustion pressure
sensing.

Might also be able to use a strain gage between a motor mount and get instant
torque per degree of rotation.   Might be useful to plot peak torque vs
combustion pressure and analyze.  

Just a brain pharte to get some thinking going on how to get a sensor that
engine management could use.