DaveRRR

Hey folks,
I just did a pair of runs in sport mode with full throttle and letting the automatic shift itself. My 1-2 shift was at 5900 and 2-3 at 6100 RPM’s. Seems low and I’m wondering if:
1- you are seeing the same?
2- could it be that this is the optimum shift point for acceleration?
3- could it be that the mild hybrid doesnt like higher RPM’s?

superswiss

That is normal. Most turbo charged engines these days use smaller turbos for low down torque and power, and less lag (larger turbos take longer to spin up = big turbo lag), but they fall flat up top, so you achieve faster acceleration by upshifting into the next higher gear early and benefit from the increased torque the engine makes at a lower rpm. Max acceleration is achieved at max horsepower. As you can see from the power/torque curve below, power goes flat once it intersects with the torque curve, so you are not gonna gain much more by staying in the current gear and power starts falling off at around 6000 rpm, so acceleration starts to slow down at that point. No point to rev it past 6000 rpm.

DaveRRR

Thanks for the explanation and the graph - yes. Fast shifting 9 speed helps as well

_jwkid

Awesome to know about the quicker shifts at lower RPMs. Have you guys seen any new W206 tuned yet?