Examining the dynamometer data
After you have performed your desired dynamometer tests, you need to take a look at the information you received. If you have a manual recording system you should calculate and transform the torque and rpm readings into horsepower numbers. If you've got a manual electronic data collection the next step will be to print out the data. On personal computer equipped dynamometers you should name the new data file and enter all the relevant data about the test run you have ended. There are software packages for your dynamometers that grant you the possibility of entering virtually any parameter you want in certain windows. This is very handy, as you can store important information in a structured data base, making it more accessible.
If you don’t own a system equipped with sensors that capture the weather conditions you should write them down as soon as you finish the dynamometer tests. It is very important to choose an appropriate output report format for reviewing the dynamometer’s data. When you examine the data received from you dyno, you should discard any information gathered during periods of rapid rpm change. You should instead concentrate on the ranges where the engine maintains a stable number of rotations for at least a few consecutive seconds. Another important step is to average the data received from the dynamometer.
Even numbers with some inertial errors can still produce valuable information after they have been averaged. If you observe any unusual numbers in your results, you have probably made some mistakes when you chose the tachometer pulse settings. Or, if horsepower is a lot smaller than you expected it to be, you should check if the throttle was wide open during the test. You should also remember about the problem of exhaust being reabsorbed into the intake system. Perform another pull, following the same procedures as the first dynamometer test, making sure you everything is checked and working properly. Remember to warm up the engine before you begin the test. On the second run, you shouldn’t make any significant parameter changes, and concentrate on repeatability instead. In fact, you are really testing the repeatability of your actions and the stability of your engine, since the dynamometer did not change between runs. Whenever possible, when chasing small improvements, you should retest the engine in its baseline state. This additional real-time check will spare you a great deal of time in the more important and longer runs.
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