Data Collection and Analysis – Beyond the Spark Plugs
This week’s adventure involved working with a supplier on a heavy duty diesel off highway application. We needed to measure pressure drops across a charge air cooler along with mass air flow and temperatures everywhere. While we don’t normally do a lot work on big diesels, the science at work here is right in line with what we’ve done for years. Interestingly, the airflows on this 775hp diesel were also right in line with what we’ve seen on lots of gasoline powered racecars.
The challenge here was to bring in data from a wide range of sensors to help paint a clear picture of what was happening at high load. Once again, our trusty MiniPEMS kit with an extra input module allowed us to bring the instrumentation lab to the field, literally. This self-contained let us record Lambda (and NOx, just for fun), thermocouples, pressure transducers, a pair of custom lab grade PMAS mass airflow sensors (scaled up versions of the ones we normally use) simultaneously.
Since the PMAS sensors come with a known transfer function from the certification flow bench, we were able to confidently quantify the system airflow. Even better, we were able to cross compare this with a backup calculated airflow generated from ECU fuel flow rate data (provided by the customer’s CAN tools) and our lambda readings. When both methods come up with essentially the same number for mass air flow, we know we’ve got it right.
All of this data collection was really just a way to get to the real question. They needed to quantify and understand the root cause of an induction system pressure drop. Not only were we able to give a confident measurement, we also worked with their team to analyze the design to identify a good way to potentially improve performance.
Our favorite comment after testing was:
“You’re the best money we’ve spent on this project so far.”
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