Optimum Power

Feb 07, 2004 2 Replies

Evening all,



Now I'm no mechanical expert, so I apologise for what may seem a basic question.



I've read through my Mini handbook and it states that for my "s" the 163bhp is reached at 4500rpm. Does this mean that there's no point going beyond this point and should change gear. My "s" revs right through to the red line with no sense of strain. (My old "Cooper" seemed to run out of puff at



5000rpm).

I ask this question because today I was "racing" a HONDA CIVIC TYPE R and I know they rev to 8000rpm and have extra power at this level. I found myself trying to keep up by making quick gear changes, whilst I could see him leaving me behind because he could keep the gear changes to a minimum.



Any ideas or experiences out there?



Cheers,



Matt, UK ...2003 "S".......and I love it!!


I don't know if the UK engine is all that different, but the US web site says the 163 hp comes at 6000 rpm. In any case, every gear shift is a pause in acceleration, so it makes sense to keep them at a minimum. Also important is where each shift puts you in the torque curve. If a shift to the next gear drops your rpms too low, you'll waste time gathering torque again.

best of luck...

Matthew Boocock wrote:

says the 163 hp comes at 6000 rpm.

Correct. I think the torque peak occurs at 4500 RPM.

If you want max acceleration, you want to shift such that overall, you're in the highest area of horsepower the maximum amount of time as you go through the gears. Most engines hit their power peak a little before redline, so the dropoff in power after shifting is the major issue. By shifting at redline, you minimize the dropoff and get max acceleration.

If redline is way after the power peak, you'd probably do best to shift so that the peak hp RPM is centered between the engine speed before and after each shift. And the shape of the hp curve around the peak might affect things. Further, while most gearboxes are fairly evenly spaced such that the RPM drop after each shift is similar, some are not which might result in different shift points for different gears.

But all this is mostly academic - on 90% of cars out there (and probably the MCS), you'll get max acceleration shifting at or very near redline.

- Mark

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