Reaching 0-60 ASAP

[kanujunkie]

just remember one thing, torque=available power to the gearbox, BHP=cock all without any torque. I'm no good at explaining physics i'm afraid Roger

Depends on gearing. If a car has twice the rpm but half the torque, it can put out similar power to a car with half the rpm but the full amount of torque   s:? :? s:?

that was why i said torque available to the gearbox

[Anonymous]

with you now stu! I was thinking low torque over many thousand rpm can = higher power than high torque over a few rpm therefore power doesnt equal cack all if you have the rpm to produce it.. which in turn brings us back to gearing..lol
Im dizzy

[Anonymous]

I don't know if any of the posted links contain the answer to the original question, but here it is from a mechanical engineer.

assuming you will be shifting more than one gear:

1:   find the difference in rpm of the engine at a set speed between the gear you are in and the next.  we will call this x rpm

2:  find the starting rpm and finishing rpm separated by x rpm which has the greatest area under the HP curve.  the upper of these points is the rpm of your shift.  the lower is the rpm you will be at in the next higher gear.

3:  repeat step two until you are in the highest gear you will be accelerating in.

4:  for your last upshift, shift at Y rpm, where the hp avalable at Y rpm first becomes less than the HP at Y minus X rpm, or, if that does not occur before redline, shift at redline.

I can think of only one situation where following these rules would not result in the best possible (max acceleration) shift points, and that is on an uphill in a situation where the last shift comes so close to the end of acceleration that the time wasted coasting in the shift would be better spent bouncing the rev limiter

Richard

[Tem]

1:   find the difference in rpm of the engine at a set speed between the gear you are in and the next.  we will call this x rpm

2:  find the starting rpm and finishing rpm separated by x rpm which has the greatest area under the HP curve.  the upper of these points is the rpm of your shift.  the lower is the rpm you will be at in the next higher gear.

That's a good rule of thumb, but not the full truth.

Say the above ends you up with a range, where your area starts and ends with 100hp. Now would it be best to change from 2nd at 100hp to 3rd with 100hp, or from 2nd at 99hp to 3rd with 101hp? The gearing does make a difference and you get better acceleration with less hp with higher gearing.

[Anonymous]

1:   find the difference in rpm of the engine at a set speed between the gear you are in and the next.  we will call this x rpm

2:  find the starting rpm and finishing rpm separated by x rpm which has the greatest area under the HP curve.  the upper of these points is the rpm of your shift.  the lower is the rpm you will be at in the next higher gear.

That's a good rule of thumb, but not the full truth.

Say the above ends you up with a range, where your area starts and ends with 100hp. Now would it be best to change from 2nd at 100hp to 3rd with 100hp, or from 2nd at 99hp to 3rd with 101hp? The gearing does make a difference and you get better acceleration with less hp with higher gearing.

No,  it sounds like you are talking height, not area under the curve...

Having maximum area under the curve between the two points mentioned rarely results in the same HP after the shift as before.  There are smart, knowledgeable people who will tell you torque is a better indicater of power at low rpm, or something similar.  In simple (slightly inaccurate) terms, acceleration is about energy, hp is a measure of energy, and the maximum average energy over the period of time (actually rpm range covered...) in a gear results in the maximum average acceleration, which is what anyone asking this question wants.

[Tem]

No,  it sounds like you are talking height, not area under the curve...

That's basically the same thing in my example, because the gearing won't change and you have to cover the same rev range.  s;) s;)

Just think about it. Choose any power/rpm point on your car. Then floor the pedal on that point. Do it with 2nd and 3rd gear, which is faster?


The area under the curve is the right answer to getting from x rpm to y rpm, but it doesn't consider gear changes. I'll try to explain it again. Say your maximum area under the curve is a symmetrical triangle, starting with 100hp at 4000rpm, going to 150hp at 5000rpm and down to 100hp at 6000rpm. That's your fastest way from 4k to 6k in one gear.

But in real life you usually have to change gears. So you do it from 100hp at 6000rpm on 2nd to 100hp at 4000rpm on 3rd. You'll notice it won't accelerate as fast on 3rd as it just did on 2nd, even though you have the same power. Now consider which is faster, 99hp on 2nd or 101hp on 3rd. Maybe it would be best to stretch beyond the maximum area under the curve on smaller gear? Just so you can get more power on the lazier bigger gear.


(...yes, if you really want to calculate it, you'll need to know the gearing, mass, wind resistance and alikes. I'm just saying it's not that simple...)

[Anonymous]

But in real life you usually have to change gears. So you do it from 100hp at 6000rpm on 2nd to 100hp at 4000rpm on 3rd. You'll notice it won't accelerate as fast on 3rd as it just did on 2nd, even though you have the same power. Now consider which is faster, 99hp on 2nd or 101hp on 3rd. Maybe it would be best to stretch beyond the maximum area under the curve on smaller gear? Just so you can get more power on the lazier bigger gear.

Which is why it's worth accelerating past peak torque towards peak BHP until diminishing returns mean that a greater level of acceleration is achievable from a higher gear, and therefore change up.

[Anonymous]

"stuff"

hey, I am not trying to convince you, I just dislike the idea that someone might search for the answer to this question, and see wrong answers which no one contested...  I am sure from your view point, you were doing the same thing.

I'm done  :-) :-) :-)

[Tem]

someone might search

Like that would ever happen  s:lol: :lol: s:lol:

[Anonymous]

someone might search

Like that would ever happen  s:lol: :lol: s:lol:

  s:lol: :lol: s:lol:    s:lol: :lol: s:lol:    s8) s8)