Quote:
Originally Posted by Natalya
A testing regimen would be like I accelerate to 10 mph then throw it in neutral and see how far the car goes before stopping. But aero drag is most prevalant at higher speeds. I could try like getting to 40 then at a certain point on a road I could throw it in neutral and see how far it travels before hitting like 25. But then I'd need to be going down this road quite a few times with no traffic there. I'd also need a suitable road.
Anyone have any ideas how I can test?
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Ideally, you want to test in both directions on a flat road and coast down from a high speed. Auto manufacturers do their track coast downs from 80 mph, but 60 to 20 mph should be fine. I'm not sure 40 to 25 would be enough. I would also recommend logging data off of the VSS over the OBD port. You have no convenient way to correct for changes in wind speed and wind direction. You might try doing several repeat runs in two directions. If you test near a weather station that logs wind speed and directional data (small airports sometimes have this accessible online) and log the times as you collect coast down data, you might also be able to download the data and correct aero for wind speed and direction after the fact.
There are lots of engineering papers on this. Coast downs are a standard procedure for determining road loads for testing vehicles on electric chassis dynamometers. Doing this on public roads in a safe manner will be difficult. Is there someplace private where you could rent/borrow/barter time (i.e., old air field, drag strip with long over-run area, private road, etc.?)