Quote:
Originally Posted by orange4boy
I have a couple of questions about a couple of possible issues with throttle stop testing. In order for this type of testing to be reasonably accurate, both the environment of the test location as well as engine power output would have to be constant over the full period of testing.
As I understand it, fuel injected cars change the air/fuel ratios pretty much constantly with changes in engine temperature, etc and the Insight, in particular, has it's lean burn mode that happens automatically. This seems to make a big difference in throttle position/speed as I have noticed and I think MetroMpg noted as well.
Are you controlling for this in your tests?
The other is atmospheric effects which can change engine power significantly, which I'm sure you are aware of. Barometric pressure can change dramatically in the space of a few hours in extreme cases, so one should probably keep tabs on that especially if tests are done on different days or times of year. Humidity also plays a role in engine power.
Have you taken these into account?
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Yes of course.
I see a display of air/fuel ratio on my dash the whole time.
My car's lean cruise mode doesn't change during the test runs (if it did change, I'd simple reprogram the MoTeC ECU so it didn't).
I do test runs back to back, with and without the aero changes - normally over a period of 15 minutes or so.
The test runs in the one aero configuration are extremely consistent (typically under 1 per cent variation in top speed).