Quote:
Originally Posted by lucid
There can be a delay depending on the conditions under which you request the shift. You can measure it when it happens. I felt it. It's been reported in press reviews. But it is pretty short and a somewhat subjective thing to consider so it would take some work to instrument things properly to be able to measure it under different conditions. This has nothing to do with the actual shift time. The lag must predominantly arise from the fact that the second clutch cannot be simultaneously pointing at the higher and the lower gear, and the system has to pick one. If you end up doing what the system has not anticipated, it will need to change the gear the second clutch is pointing at, which will cause a slight delay. No way around that unless you have a third clutch and both possibilities are always covered (2nd clutch pointing at the lower gear, 3rd clutch pointing at the higher gear). In the dual clutch system, the chance of requesting a gear the computer has not anticipated probably depends on how well the computer can predict what you want to do next depending on throttle input and engine speed and maybe some other variables. It makes sense for the computer to be conservative and pick the lower gear in normal driving conditions in low-mid range rpms since the lower gear is where the power is in case you want to accelerate quickly (for peak acceleration, the sensible thing to do would be to downshift and floor it rather than floor it in the current gear). So, the delay seems to be absent for a downshift when you are cruising around calmly. I don't see this being an issue when you are driving aggressively at high revs as what you want to do should be much more transparent to the computer in that case. That said, in objective terms, I don’t know that this is a major issue overall.
However, even if you experience a delay under certain conditions, I'm pretty sure:
the delay + DCT shift time < human MT shift time.
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that makes a lot of sense. i am a MT guy, but I know I won't be beating DCT anyday when it comes to shift times.