Hi all,

I'm building an onboard computer that will be handling all of my displayed gauge values (in-dash), data logging and real-time warnings, and had a few questions I wanted to open to the community.. Basically I want the system to warn when certain thresholds are hit during certain conditions (for engine safety, transmission safety or personal safety). When on a road racing track you typically can't stare at your gauges for indication of an issue, so I want audible warnings where possible. Also, for many parameters, reviewing after a session could be too late (especially if the engine goes during a session). So the issue now is what are good thresholds and conditions? Here are my estimates for safe default warning conditions (I know each car is likely to be different):

1) AFR ratio at WOT >13 (may need to have different limits based on RPM)
2) Knock count at WOT >0 (above 6000RPM)
3) EGT temps >900C (need to do more testing on this)
4) Timing - rapid rate of change at WOT above 6000RPM. Since timing is pretty dynamic, should probably just watch for a quick change in the values indicating the ECU is pulling timing.
5) Oil temps >100C or <80C
6) Water temps >90C or <80C
7) Oil pressure - this one needs to be scaled with RPM. So <20PSI at idle and <100PSI at redline
8) Boost. This depends on the tune/car (in my case 37PSI should be the limit)
9) Fuel rail pressure < ((43.5+boost)-5) (subtracting 5psi here for variability)
10) Transmission oil temperature - need to figure out good values for this.
11) Are TC oil and/or diff oil worth measuring in real time and warning on?
12) Tire pressures - sudden loss, excessive discrepancy, etc

Let me know if you guys can think of any additional critical conditions to warn on, or if the above conditions need altering (thresholds or conditions). I know that some of the values may seem redundant (e.g. technically AFR will basically warn you about fuel pressure, or knock count typically affects timing), but I think it's better to warn on each individual parameter so you know as quickly as possible what the issue might be.

I'm also thinking about making the software more intelligent where the system learns the limits based on normally seen values... This could negate most of the hard coded values, and could allow for more granular thresholds (e.g. it could know the expected values throughout the rev range at various temperatures, including ambient which could change charge temperature and pressure altering all the expected limits).

Thanks!

S.