PatO,

It is true that for a given gear the car will accelerate hardest at its torque peak.

However, for a given vehicle speed the car will accelerate hardest at its torque peak.

Power is rate of change of kinetic energy. If you want to accelerate the vehicle you want to increase its kinetic energy. It is really that simple.

The torque at the engine is not what is important. It is the torque at the rear wheels that accelerates the vehicle. To maximize the torque at the rear wheels you want to be at the power peak of the engine.

If you are at the torque peak in a given gear, you will accelerate hardest in that gear, but if you downshifted and the engine was now at a higher RPM and power level, you will accelerate harder in the new lower gear. This is because the torque t the rear wheels will increase even though the torque at the engine will decrease. (Due to the magic of gear ratios) assuming the shift brings you to a higher engine horsepower, the lower gear will multiply the torque at the engine to a greater amount than would be presant in the higher gear at the torque peak.

Torque at the rear wheels is what is important, not torque at the engine. To maximize torque at the rear wheels for any vehicle speed you want to be at the power peak.

I am not a military buff but there s a turbine powered tank (I think it is the M1). The thing makes the torque of your average buick. ~250 ft*lbs. But it makes that torque at some ungodly RPM so it has a huge horsepower output. (I am not sure, but would guess the operating RPM is in the 50,000 to 100,000 RPM range) By the time you get done gearing down the 250 ft*lbs available at 50,000 rpm, the torque at the rear cogg (or wheel) is huge.

Power is King.

-Joe

posted by 198.208.2...

• Q: if the engine is designed to give a flat torque..., TB, Fri, 1 Mar 2002 13:20:31
  • power vs torque, Thomas L, Fri, 1 Mar 2002 19:02:30
    • Wait a minute!, PatO, Fri, 1 Mar 2002 22:05:43
      • But you forgot . ., Jim, Fri, 1 Mar 2002 23:09:53
        • Excellent post n/m, Thomas L, Sat, 2 Mar 2002 14:55:42
          • Re: Thanks. n/m, Jim, Sun, 3 Mar 2002 21:54:55
        • Re: But you forgot . ., Eli5, Sat, 2 Mar 2002 13:04:55
        • Re: But you forgot . ., PatO, Sat, 2 Mar 2002 09:20:42
          • "in a given gear" is irrelevent, Jim, Sun, 3 Mar 2002 11:41:44
          • Really????, Thomas L, Sat, 2 Mar 2002 15:01:24
            • Re: Really????, PatO, Sat, 2 Mar 2002 18:30:44
              • Typo, PatO, Sat, 2 Mar 2002 18:33:28
                • Re: Typo, 2Slow, Mon, 4 Mar 2002 09:10:46 <-- Viewing This Message
                  • My own typo..., 2Slow, Mon, 4 Mar 2002 12:07:42
                  • Didn't the M1 have a serious design flaw..., zeke, Mon, 4 Mar 2002 10:17:47
                • Clarification, Thomas L, Sun, 3 Mar 2002 04:48:38
        • I may be wrong-, Dennis, Fri, 1 Mar 2002 23:30:34
          • Re: I may be wrong-, Jim, Sat, 2 Mar 2002 00:46:29
  • Re: Q: if the engine is designed to give a flat torque., Al, Fri, 1 Mar 2002 16:07:54
    • experimental data:, Eli5, Sat, 2 Mar 2002 12:52:29
    • Re: Q: if the engine is designed to give a flat torque., BrooksG, Fri, 1 Mar 2002 16:55:26
      • I don't consider 5th an overdrive..., Bob M, Sat, 2 Mar 2002 11:21:00
  • lower rpms for same speed?..., bob m, Fri, 1 Mar 2002 14:00:00
    • darn enter button..., bob m, Fri, 1 Mar 2002 14:00:50
      • Faster as in 160+ mph? n/m, Eli5, Fri, 1 Mar 2002 16:01:15
        • Yep -- 150 anyway. n/m, Bob M, Sat, 2 Mar 2002 11:13:54

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