Power roll off above 7000 rpm

[tomhole]

Whenever I drive my Z4M I always take every opportunity to max the rpm's before shifting to 2nd and 3rd (haven't had the opportunity to max out 3rd gear yet. I imagine that exceeds most speed limits by a wide margin). I have noticed that every time I do a WOT acceleration to 60 mph, the car pulls great until around 7000 rpm and then has a noticeable decrease in pull above that. I found a hp vs. rpm curve from a dyno run on the MR and the data seems to support this observation. HP goes up fairly linear until 6000 rpm and then flattens out significantly from 7000 to 8000. Interesting that torque stays flat through 6000 rpm and starts diving after that. That seems to indicate HP is not going up as fast after 6000 rpm (since the two are mathematically related).

Seems to me a shift at 7000 rpm or below would be more quicker than letting it go all the way to 8000.

Just an observation.

Tom

[Kgolf31]

You're right Tom.

I usually short shift into 2nd to gain the extra torque in the lower band.

[ga41]

Perhaps others have first hand experience but my mechanic commented how my Z4M's power trails off sooner in the top end (like you mention tomhole) than the E46 M3... Always wondered why that would be so...