Is this the Diagnostics Holy Grail?

[Pingu]

In-Cylinder Pressure Analysis

To optimise your engine, the in-cylinder pressure (the pressure in the cylinder when the engine is running) should be:

a) Maximised
b) Balanced across all cylinders
c) Peak at the same time in the cycle
d) Peak at the optimum time in the cycle

Most people can measure the static peak pressure (engine not running), but not many have even tried to measure the pressures with the engine running. Now you can. You just have to spend about $5,000...
http://www.tfxengine.com/index.html

You can even get modified sparkplugs, so you don't have to drill your cylinder head...
http://www.optrand.com/

You can test the engine a lot more cheaply, but less accurately with this...
https://www.picoauto.com/products/automotive-oscilloscope-kit/overview
It will allow you to test the engine by checking for "blips" in the battery lead. It will show you unbalanced cylinders (amongst many other things), but for a fraction of the cost of a proper in-cylinder test.


Unfortunately, I'll just have to make do with my normal present from Santa...

 

[t-tony]

If you had to wait for it you might not live that long mate

Tony.

 

[NZ00Z3]

..

 

[Pingu]

How does this differ from the rough running chart in INPA?

Knock Measurement v. In-Cylinder Pressure Measurement is widely discussed amongst the many forums that I visited last night.

The conclusion that I came to was that Knock Sensors are good for determining that there is a problem, In-Cylinder Measurement is good for determining where that problem is on the engine cycle. Here's a good image to show what I mean...

Using live in-cylinder pressure measurement, you would be able to retard the peak pressure to a point where the engine is running, and then advance to the point where "knock" starts, then retard a few degrees.

You could then take the car for a blast and ensure that "knock" doesn't occur at any time.


Using conrod / stroke geometry, you can also work out where you want the peak pressure to occur - you can tweak your engine for that.

The potential is absolutely awesome. 15 years ago, it was even too expensive for NASCAR ($100,000ish for a basic setup). It was only Formula1 and dyno test cells that could afford it. Formula1 could afford it because they are rich and they can afford to make bespoke probes to access the cylinder. Dynos could afford it because they are static and it is easy to access the engine, so holes could be drilled in cyl heads and awkward shaped probes can be used, etc. (this brings the cost down by a factor of 10). Now, it's around $5000 and this includes a $1500 sparkplug with an integral probe.

Hopefully, in another few years it will be in our price bracket.