I do this all day every day as I am a calibrator for an OEM. I will ask around and see what some people know. Most are out on vacation until the beginning of the year, I will see what I can find out then.
Thanks...that'd be appreciated.
To be more specific for those interested, the sensors we typically use are these (or similar). They are specifically made for in-cylinder combustion work:
https://www.kistler.com/?type=669&fid=54410&model=document&callee=frontend
What exactly are you trying to read? Pressure, temp, understand flame front, understand how the fuel's moving?
This is the type of testing that engine companies spend big bucks on typically.
I understand it's not cheap, but we have the supporting infrastructure in place...my question was mostly on where to source a head that was drilled and tapped for the sensors. Or if anyone had information on where the head could be drilled.
Obviously, these heads don't have glow plugs, so it necessitates drilling a new hole. I've never tried to do this on a 5.9/6.7 head, so looking for information before we start experimenting. Sometimes it can be tricky to miss water jackets, etc. Casting shift and variations can also make the job more challenging. I figured as long as these engines have been around, that there may be a chance someone has "been there and done that" and could provide some info.
We also use Bosch piezo knock sensors (looks like from a car) to measure the shock wave of pre-combustion. it works but not near as accurate at the pressure sensor. This may be an option since you simply bolt these on to the head directly. No need for a pressure port to be drilled in the head.
Interesting...I'll look into specs on these.
Real-time cylinder pressure must be the holy grail of engine tuning.
Yes, it is! Typically this type of work is done in conjunction with a quadrature encoder on the crankshaft; we typically use 1800 pulse/rev to give 0.2° resolution.
This is the software that we're moving to on the newer setups:
NI Combustion Analysis System Software for NI LabVIEW - National Instruments
In simple terms, it let's you look at things like:
- Pressure trace...you can see the in cylinder pressure real time with respect to the crankshaft. Obviously max pressure is of interest, but the shape of the curve gives alot of info as well
- PRR...pressure rise rate...the "rate" at which the pressure initially rises due to combustion is paramount. Usually 10 bar/degree is considered the upper limit for production; in the research environment you may see 10x that (but not for long)
- IMEP...indicated mean effective pressure...the "indicated" work that is being done on the piston
- MFB...mass fraction burned...common points are 5, 10, 50, and 90 percent points
- HRR...heat release rate
- Cylinder balancing...presuming you have multiple cylinders instrumented. When looking at advanced combustion modes, balancing becomes critical as you push things to the edge of stability
Yes, but the real trick is know exactly where TDC is...
This can be done by physically aligning the pulse on the encoder with TDC using an oscilloscope. But we have a capacitive probe from AVL that allows you to do this dynamically with greater accuracy. Max pressure in the cylinder doesn't occur exactly at TDC.
I might have pictures of a transducer in a 6.7 head.
This could be helpful!
Thanks for the help everyone...
--Eric
