Is tyre slip caused by power or torque?

[alelanza]

Is a car more likely to spin its wheels when its engine is at peak HP or at peak torque?

[Mystery Steve]

Yes...

[machin]

Hasn't this topic been covered before? My opinion is this:-

The wheel's are most likely to spin when the force at the tyre contact patch is highest... this occurs when the gear ratio is lowest and when the engine torque is highest... so my answer is "when the engine is at peak torque."

[Gecko]

It depends on the situation you consider.

If you are in a fixed gear, then, when keeping the car in the same gear, there will be more likelihood of wheel spin at the revs and therefore the car speed where the engine has top torque.

If you have two different gears at the same car speed, one keeping revs at top torque and the other at top power, then there will be more wheel spin in the lower gear where you are running at top power.

[autogyro]

The question cannoy be answered without more data.

[Giblet]

Yes...

...if the car is going around a high speed corner, monkey wrenches everywhere.

Where does an F1 engine that revs to 18,000 produce these two values roughly?

[alelanza]

Hasn't this topic been covered before? My opinion is this:-

I did ask the question in another topic, but didn't really get an answer beyond 'i think this or that'. So i was hoping by opening a separate topic i would get something more concrete.

The wheel's are most likely to spin when the force at the tyre contact patch is highest... this occurs when the gear ratio is lowest and when the engine torque is highest

If you are in a fixed gear, then, when keeping the car in the same gear, there will be more likelihood of wheel spin at the revs and therefore the car speed where the engine has top torque.

Yes fixed gear, so force is higher on max torque than max power? alright thanks guys.
If anyone can add any numbers to this i'd be most happy

[alelanza]

Yes...

...if the car is going around a high speed corner, monkey wrenches everywhere.

Where does an F1 engine that revs to 18,000 produce these two values roughly?

See that's what makes me think top power is more likely to spin them. Why would the engine range that produces more thrust would be less likely to spin the wheels.. that's what's on my head

[Mystery Steve]

Rather go into the detail, I'll just quote Jersey Tom's blog:

http://fsae1000.blogspot.com/2009/11/to ... gines.html

[Jersey Tom]

It depends on the situation you consider.

If you are in a fixed gear, then, when keeping the car in the same gear, there will be more likelihood of wheel spin at the revs and therefore the car speed where the engine has top torque.

If you have two different gears at the same car speed, one keeping revs at top torque and the other at top power, then there will be more wheel spin in the lower gear where you are running at top power.

This.

Kind of a weird question though. The way it was worded originally I'd just go with peak torque (assuming you're in one gear).

[autogyro]

It depends on the situation you consider.

If you are in a fixed gear, then, when keeping the car in the same gear, there will be more likelihood of wheel spin at the revs and therefore the car speed where the engine has top torque.

If you have two different gears at the same car speed, one keeping revs at top torque and the other at top power, then there will be more wheel spin in the lower gear where you are running at top power.

This.

Kind of a weird question though. The way it was worded originally I'd just go with peak torque (assuming you're in one gear).

That would all depend on what gear ratio, the tyre might only break traction when the engine revs were higher than max torque and round and round the question goes.

[alelanza]

Rather go into the detail, I'll just quote Jersey Tom's blog:

http://fsae1000.blogspot.com/2009/11/to ... gines.html

Thanks, will read it from home as it's blocked here at work

That would all depend on what gear ratio

Any gear ratio, the answer should be the same methinks. What do you figure?

[autogyro]

Try a gear ratio of 1000 to 1 and see if max torque breaks traction before high rpm. To many variables.

[alelanza]

Mystery Steve wrote:Rather go into the detail, I'll just quote Jersey Tom's blog:

http://fsae1000.blogspot.com/2009/11/to ... gines.html



Thanks, will read it from home as it's blocked here at work

Done reading. It's all well and good, but either it doesn't answer my question or it just flew past me.

Try a gear ratio of 1000 to 1 and see if max torque breaks traction before high rpm.

Can't, my car even on 4L is rather distant from 1000:1

To many variables.

Or just assume 'all else being equal'. Say you have an rx-8:

232 hp @ 8500 rpm
159 lb-ft @ 5500 rpm

Put it on 1st gear. Is it more likely to break traction at 8.5k or 5.5k rpm? Of course you'll say, it'll spin the tyres in both cases, and you'd probably be right.
So say you start putting weight over the rear axle, 100 Kg at a time, will it stop spinning the tyres at 8.5 or 5.5 first?
And yes, assume you put new tyres and clutch every run, and engine temp, and air pressure, and any other potential variables remain the same. Driver is a robot of course.

[autogyro]

As you add weight the drive wheels will grip to higher rpm until you reach 5.5 thousand rpm but that is only because you reach 5.5 before you reach 8.5.
If you carry on adding weight you will reach a point where 8.5 has to be reached before traction is broken.
The point being?