I sent a PM but your box is full. Additionally, other might be curious about combustion pressure so I made a post from the message.

So, you want to measure cylinder combustion pressure; that isn’t cheap. There are no simple gauges for this. You have to tap into the head, missing any oil or coolant passages, for a mechanical gauge. This can also be used for an electrical sensor but still questionable with the work required on the head.

The best method which is used by all major automotive manufacturers and large racing teams are peizo pressure sensors built into the spark plug. We are the southeast representative for Kistler who is one of the leaders in this technology so we deal with some of the NASCAR teams in the Carolina's.

Spark Plug Sensor

But the problem is cost. In addition to the sensor which runs in the $2500 - $3500 range you also need a charge amplifier which costs anywhere from $2000 - $6000. So expect a minimum of $6000 to continuously measure cylinder combustion pressure.

Measuring cylinder pressure with the engine off is easy; $30 gauge to do a compression test. But in car and continuous measurements are difficult and expensive.

Just use an EGT gauge to determine what is going on. You'll want to keep it below 1500 degrees F. And this can be had for under $100.

Take care,
Steve