QTS car lowering and acceleration performance

[Rocket Punch]

See Scaff's explanation in post #7 or click here

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I've noticed something very strange when I am tuning cars in QTS. I noticed that as you lower the height of the car the performance of your cars acceleration will be lowered (not the acceleration time).

So according to the QTS your car will accelerate slower as you lower your car?

 

[magburner]

I'm not technically minded at all, but I though Acceleration had something to do with weight transfer from front to back. Therefore, I'd assume the lower a car is, the less weight can transfer onto the back wheels giving less grip, and less acceleration.

I may be wrong though...

 

[Magneto]

Lowering gives less air under the car, and less turbulens under the car, thus maybe not getting time lower but definetly NOT higher. Though it increases stability at high speeds.

 

[jgda9rs]

i think it's true, maybe that's why we dont see a lot of drag cars being lowered all the time. but then again i guess it depends on your camber and toe settings, and maybe in real life your tire pressures would also make a difference. and it depends on how much you lower the car i guess ? i could be wrong.

 

[Rocket Punch]

I'm not technically minded at all, but I though Acceleration had something to do with weight transfer from front to back. Therefore, I'd assume the lower a car is, the less weight can transfer onto the back wheels giving less grip, and less acceleration.

I may be wrong though...

Lowering gives less air under the car, and less turbulens under the car, thus maybe not getting time lower but definetly NOT higher. Though it increases stability at high speeds.

i think it's true, maybe that's why we dont see a lot of drag cars being lowered all the time. but then again i guess it depends on your camber and toe settings, and maybe in real life your tire pressures would also make a difference. and it depends on how much you lower the car i guess ? i could be wrong.

May be I didn't explain myself well enough.

I am trying to say that there is another bug in this game.

 

[Racer XO]

May be I didn't explain myself well enough.

I am trying to say that there is another bug in this game.

LOL...Touche I didn't notice that thanks for the heads up Rocket Punch.

btw guys, lowering suspension also lowers the center of gravity which decreases weight transfer that helps allow for more traction...i.e quicker acceleration

 

[Scaff]

LOL...Touche I didn't notice that thanks for the heads up Rocket Punch.

btw guys, lowering suspension also lowers the center of gravity which decreases weight transfer that helps allow for more traction...i.e quicker acceleration

That depends entirely on which wheels are driven, you are correct in saying that cog height is a factor is load transfer and that the lower a COG is the less load will transfer.

Under acceleration we are talking transfer to the rear of course, with a rear wheel drive car a reduction in load transfer to the rear means less grip at the rear (as grip is a direct result of load x co-ef of friction) and theoretically reduced acceleration. The opposite would be true of front wheel drive cars, and for 4 wheel drive cars it would depend on the torque split.

Lets look at an example.

A 2500lb RWD car with a 50:50 weight distribution and with standard ride height it transfers 10% of its load to the rear under a standing start, that would give us a load distribution of 1500lbs at the rear and 1000lbs at the front. Take a nice easy co-eff of friction of 1 for the rear tyres and we end up with the rear tyres being able to handle approx 1,500ftlbs of torque before starting to loose grip. As engine torque is multiplied by the drivetrain, we could exceed that in 1st gear quite easily.

Now we lower the ride height and its effect is to reduce the load transfer to 8% to the rear, our new figures are 1450lbs at the rear and 1050lbs at the front, our rear tyres can now handle 1,450ftlbs of torque. It is only a reduction of 50ftlbs, but its still a reduction and as such we will now not be able to dial in as many RPM before the tyres slip and as such will now be dealing with reduced acceleration.


The very reason why a 911 obtains standing start times far better than its engine output would suggest is that it has a lot of load over the rear tyres, load that increases as the car accelerates. Its also why the will always initially understeer as the load coming off the front tyres is dramatic.

Reduction in ride height and its effect on load transfer can most certainly effect acceleration figures, but in what way depends on a number of factors, such as driven wheels, initial weight distribution, how much the ride height changes, etc. You just can't simply say that it will not effect acceleration or that it will only effect it one way.


Regards

Scaff

 

[Rocket Punch]

That depends entirely on which wheels are driven, you are correct in saying that cog height is a factor is load transfer and that the lower a COG is the less load will transfer.

Under acceleration we are talking transfer to the rear of course, with a rear wheel drive car a reduction in load transfer to the rear means less grip at the rear (as grip is a direct result of load x co-ef of friction) and theoretically reduced acceleration. The opposite would be true of front wheel drive cars, and for 4 wheel drive cars it would depend on the torque split.

Lets look at an example.

A 2500lb RWD car with a 50:50 weight distribution and with standard ride height it transfers 10% of its load to the rear under a standing start, that would give us a load distribution of 1500lbs at the rear and 1000lbs at the front. Take a nice easy co-eff of friction of 1 for the rear tyres and we end up with the rear tyres being able to handle approx 1,500ftlbs of torque before starting to loose grip. As engine torque is multiplied by the drivetrain, we could exceed that in 1st gear quite easily.

Now we lower the ride height and its effect is to reduce the load transfer to 8% to the rear, our new figures are 1450lbs at the rear and 1050lbs at the front, our rear tyres can now handle 1,450ftlbs of torque. It is only a reduction of 50ftlbs, but its still a reduction and as such we will now not be able to dial in as many RPM before the tyres slip and as such will now be dealing with reduced acceleration.


The very reason why a 911 obtains standing start times far better than its engine output would suggest is that it has a lot of load over the rear tyres, load that increases as the car accelerates. Its also why the will always initially understeer as the load coming off the front tyres is dramatic.

Reduction in ride height and its effect on load transfer can most certainly effect acceleration figures, but in what way depends on a number of factors, such as driven wheels, initial weight distribution, how much the ride height changes, etc. You just can't simply say that it will not effect acceleration or that it will only effect it one way.


Regards

Scaff

Good explanation. I can confirm that is the case in QTS.