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I am curious about how one car can have a much higher speed through turns in twisty tracks compared to another that has similar skid pad results. For example, take two sports cars (such as the Elise non-LSS vs. Corvette ZR-1 suspension or a Porsche 911) and assume that they have the same skid pad result (for example, 1 G). Also assume that they both don't have much body or tire roll through the turns. Assume the turns are twisty enough that top end horsepower is not the limiting issue. Also assume that the sharpness of the turns is within the turning radius of both cars. Also assume equally good drivers.

So, why would one car go through the twisty turns much faster than the other? (Elise faster than Corvette and 911 through the turns, according to the posts at this site.) Of course one is heavier than the other, but if their skid pad results are the same, how would it matter? About all I can think of is that the angular inertia of the lighter, smaller car allows it to essentially change rotation speed (angular acceleration) quicker, but I am not sure that the traction of the tires that leads to the same skid pad result would not also lead to a comparably rapid angular acceleration of the car (that is, nimbleness).

I actually know quite a bit about physics, and could make up some explanations, but I was wondering if anyone has some more definitive knowledge. I am sure this must have been studied by automotive engineers.

I ask not only because I am curious by nature, but also because I have told some folks about the Elise and how it goes through twisty tracks so much faster than most anything else, but I can't explain why in the case of similar skid pad results. I can't be the only one here wondering about this.
 

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My understanding is that the skidpan test is performed on a specific radius curve at more or less constant speed.

Its sort of a maximum grip possible in optimal conditions test.

So it doesn't take into account weight transfer, suspension dynamics, variable radius turns etc.

Cheers

NevB
 

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Skidpad tests do not measure max cornering load.

Maximum cornering load is achieved off the pedals when all available traction is used for lateral load and no traction is used for accelerating, braking, or holding a constant speed (like on a skidpad).

A car will always reach a higher lateral load on a track (mid-corner, off the pedals) than on a skidpad.

Comparing the cornering speed of two cars as a way of determining which one can support a higher corning load is only relevant if they drive the same lines (ie, have the same power/weight ratio.) For any given turn, the more power a car has, the later the apex, and the lower the cornering speed. So if the cars do not have the same power/weight ratio the comparison would not be "apples to apples"

So if you put a rev limiter on the Elise so it only had 100 hp, you would observe an increase in cornering speed around the track. But it would be pulling the same lateral gs in the corners as before.

911 and Elise is a fair comparison because they would probably drive similar lines. In this case if you observe a higher corning speed with the Elise it really means it can support more gs.
 
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