UK Karting - Notice Board (General Karting) : Re: Davidmc is this correct?

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Re: Davidmc is this correct?
Posted by 'davidmc' on 21 Aug 2009 @ 09:57

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davidmcJoined: April 2003
Total Posts: 2
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Not quite. You are correct that peak acceleration occurs at peak torque in any given gear. Now, before we go out on the circuit in our fixed gear kart, we get to choose what that gear is. This is where QoT is correct. We choose the gear that maximises the area under the POWER curve.

Why would we do that? Because getting round a circuit quickly isn't about maximising acceleration (if it were, we'd just fit a bigger rear sprocket). You want to apply the largest force, over a distance (the length of the lap) in the shortest possible time.

Go back to the definitions of Work and Power. Work is Force over a distance. Power is work per unit time. Does that not make Power sound like "applying the largest force, over a distance in the shortest possible time"? As you can see from the formula:

Power (getting work done) = Force (acceleration) * Speed

By altering your gearing, you are trading accelerative ability for speed, and this is something you know intuitively.

Now go back to the original question of the thread. Peak power or peak torque? Why would I say peak power is largely irrelevant? Because, in a kart, without the benefit of gears, over the speed range of the circuit, we only operate at peak power at one speed. Higher torque would be more indicative of the overall performance of the engine (chances are, more torque will equate to more power). Higher power could just mean you have a peaky dog (fine withs gears, bad without).

Dave

Message Thread:

bhp or torque by 'KJM' (17 Aug 2009 @ 17:31)

Re: bhp or torque by 'davidmc' (17 Aug 2009 @ 17:46)

Re: bhp or torque by 'PaulMRotax' (17 Aug 2009 @ 18:30)

Re: bhp or torque by 'davidmc' (17 Aug 2009 @ 19:20)

Re: bhp or torque by 'QuickOldTimer' (17 Aug 2009 @ 19:20)

Re: bhp or torque by 'davidmc' (17 Aug 2009 @ 19:22)

Re: bhp or torque by 'KJM' (17 Aug 2009 @ 19:38)

Re: bhp or torque by 'QuickOldTimer' (17 Aug 2009 @ 22:44)

Re: bhp or torque by 'davidmc' (18 Aug 2009 @ 0:14)

Re: bhp or torque by 'QuickOldTimer' (18 Aug 2009 @ 9:49)

Re: bhp or torque by 'davidmc' (18 Aug 2009 @ 13:05)

Re: bhp or torque by 'QuickOldTimer' (18 Aug 2009 @ 13:51)

Re: bhp or torque by 'davidmc' (18 Aug 2009 @ 15:10)

Re: bhp or torque by 'QuickOldTimer' (18 Aug 2009 @ 15:43)

Re: bhp or torque by 'davidmc' (18 Aug 2009 @ 23:41)

Re: bhp or torque by 'QuickOldTimer' (18 Aug 2009 @ 23:57)

No ! , the original qustion was... by 'Chads' (19 Aug 2009 @ 0:58)

Re: No ! , the original qustion was... by 'QuickOldTimer' (19 Aug 2009 @ 1:11)

Re: No ! , the original qustion was... by 'davidmc' (19 Aug 2009 @ 8:36)

Re: No ! , the original qustion was... by 'QuickOldTimer' (19 Aug 2009 @ 11:31)

Re: No ! , the original qustion was... by 'davidmc' (19 Aug 2009 @ 12:27)

Re: No ! , the original qustion was... by 'Hi99' (19 Aug 2009 @ 19:15)

Re: No ! , the original qustion was... by 'TanglerTKM' (19 Aug 2009 @ 22:48)

contd by 'TanglerTKM' (19 Aug 2009 @ 22:51)

Re: contd by 'davidmc' (19 Aug 2009 @ 23:57)

Re: No ! , the original qustion was... by 'davidmc' (19 Aug 2009 @ 23:40)

Re: No ! , the original qustion was... by 'Hi99' (20 Aug 2009 @ 20:13)

Davidmc is this correct? by 'Hufggfg' (21 Aug 2009 @ 8:33)

Re: Davidmc is this correct? by 'davidmc' << You are here!

Re: Davidmc is this correct? by 'Hufggfg' (21 Aug 2009 @ 12:02)

Re: Davidmc is this correct? by 'davidmc' (21 Aug 2009 @ 13:07)

KJM, your best means of altering .. by 'Chads' (18 Aug 2009 @ 2:13)

Re: KJM, your best means of altering .. by 'KJM' (19 Aug 2009 @ 9:39)

David, that doesn't make sense by 'Booney' (19 Aug 2009 @ 23:19)

Re: David, that doesn't make sense by 'davidmc' (19 Aug 2009 @ 23:53)

Maximum accel is at max torque by 'PhilOwen' (20 Aug 2009 @ 17:28)

Re: Maximum accel is at max torque by 'QuickOldTimer' (20 Aug 2009 @ 20:59)

Re: QOT by 'John' (20 Aug 2009 @ 22:18)

Re: QOT by 'QuickOldTimer' (20 Aug 2009 @ 22:26)

Re: QOT by 'John' (20 Aug 2009 @ 23:51)

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