I used the same formula to calculate shift points for my MGB. Save
yourself the time:
1st->2nd 4800rpm
2nd->3rd 4700
3rd->4th 4100
Thomas James Pokrefke
1970 MGB
pokrefke@ocean.st.usm.edu
http://ocean.st.usm.edu/~pokrefke
>
> Someone asked for the shift points. I assume that you want them for optimum
> acceleration. I have looked up some information - it is available in the
> July 1988 issue of Road and Track, and the October 1993 issue of road and
> track. Basically, it says:
> <snip>
> a car will accelerate most quickly if each shift drops the revs back to the
> torque peak, regardless of where the horsepower peak may be. Often, this
> means going all the way to redline - and still the revs may be too low in
> the next gear.
> <snip>
> For example, the '85 Toyota MR2 (sorry for the non british example) has a
> redline at 7700rpm, peak horsepower at 6600 rpm, and peak torque at 4800
> rpm. First and second gear ratios are 3.17 and 1.90. So to shift from 1 to
> two and get the maximum acceleration:
>
> 3.17
> ------ x 4800rpm = 8000rpm
> 1.90
>
> but you really shouldn't exceed redline, so shift at 7700. The third gear
> ratio is 1.31, so for the 2 to 3 shift:
>
> 1.90
> ------ x 4800rpm = 6960rpm
> 1.31
>
> <snip>
> They also mention that things get kind of screwy when you have a very flat
> torque curve. As (the example they have) when you have a turbocharged car
> such as a Saab turbo. For this car, the shift points are at 1 to 2 at
> 3745rpm and 2 to 3 at 2908rpm, as the peak torque occurs at 1950rpm. With
> the flat torque curve, the shift point is definitely less important.
> Phil Bates
> 58 MGA
> 67 MGB
> 75 Jaguar XJ12C
> 52 MG TD replicar (VW)
>
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