addison

When is it best to change gear, when accelerating for max speed?

1) on the point of max torque

2)on max BHP

3) none of the above.


Dose max torque and max BHP arrive at different rev's in different gear's

scoobysteve2286

i always thought it was 1000 rpm before the redline is best point to change gear... i could be wrong though

pete.wilson

For max acceleration, you should change at max power (which may or may not be where the red line is). In an ideal world the needle should remain between max torque and max power, but depending on the drop in gear ratios this is not always possible.

Pete

TonyBurns

iTrader: (3)

Sometimes you can feel the power dropping off (especially on a standard car) and that can be 1500rpm below the red line in the higher gears but for most of the time its as steve said, about 1k below the red line as you will have already gone beyond the peak power.

Tony

T5NYW

iTrader: (4)

Pete

i'd agree you "if" gear ratios allowed, change up on max Power RPM and arrive in next gear at max torque RPM would be perfect.

Tony

T5NYW

iTrader: (4)

Not sure if this might help or Hinder you in making a judgement call

making loads of assumption and some approx power graph fiquires given to me, not including losses, loading, drag etc etc and VERY rough calculation of final speed (5-10% out) etc etc IIRC IMHO flame suit on

UK Approx boost rpm 6200 - 2300
JDM Approx boost rpm 7200 - 2100

UK 3.636 / 2.235 / 1.521 / 1.137 / 0.971 / 0.756 -UK Sti 2.0ltr or 2.5ltr

1st 31- 11.5mph = 21.5mph on boost speed in gear
2nd 50mph - 19mph = 31mph in gear on boost
3rd 74mph - 27.5mph = 45.5mph in gear on boost
4th 99mph - 37.5mph = 61.5mph in gear on boost
5th 116mph - 43mph = 73mph in gear on boost
6th 149mph - 55.5 mph = 93.5mph in gear on boost

1st max speed @ max Rpm 35mph
2nd max speed @ max Rpm 57mph
3rd max speed @ max Rpm 83.5mph
4th max speed @ max Rpm 112mph
5th max speed @ max Rpm 131mph
6th max speed @ max Rpm 168mph (speed limited)

JDM 3.636 / 2.375 / 1.761 / 1.346 / 1.061 / 0.842

1st 36.5 - 10.5mph = 26mph in gear on boost
2nd 56mph - 16mph = 40mph in gear on boost
3rd 76mph - 21.5mph = 54.5mph in gear on boost
4th 99mph - 28mph = 71mph in gear on boost
5th 126ph - 36mph = 90mph in gear on boost
6th 158mph - 45.5mph = 112.5mph in gear on boost


1st max speed @ max Rpm 40mph
2nd max speed @ max Rpm 61mph
3rd max speed @ max Rpm 82mph
4th max speed @ max Rpm 108mph
5th max speed @ max Rpm 137mph
6th max speed @ max Rpm 173mph (speed limited)



Tony

T5NYW

iTrader: (4)

MY06 JDM STi Type 20

Max torque 460nm at 3800rpm (4th gear)
Max Power350 Bhp at 7155rpm

1st gear 0mph best torque 18mph change up 38mph
2nd gear 38mph best torque 29mph change up 55mph
3rd gear 55mph best torque 39mph change up 74mph
4th gear 74mph best torque 51mph change up 96mph
5th gear 96mph best torque 65mph change up 122mph
6th gear 122mph best torque 82mph best bhp 154mph

MY02 UK STi 2.0ltr

Max torque 390nm at 4000rpm (4th gear)
Max Power 295 Bhp at 6000rpm

1st gear 0mph best torque 21mph change up 30mph
2nd gear 30mph best torque 32mph change up 49mph
3rd gear 49mph best torque 48mph change up 74mph
4th gear 74mph best torque 64mph change up 96mph
5th gear 96mph best torque 75mph change up 112mph
6th gear 112mph best torque 97mph best bhp 144mph

I'd consider 1&2nd 6300rpm and 6000rpm rest