Non linear PP ballast adjusting

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wlashack

wlashack

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wlashack
Helllo,
I found that adding ballast does not affect PP as I would expect. You often find spots where adding another kg of ballast increases the PP which looks strange to me.
I am not a tuner so I ask - is this ok or is it a bug in gt7? Thanks.
 
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More weight can give more traction on driven wheels, better balance leading to faster cornering, or ability to brake more effectively with all wheels. The PP system calculates the points by some simulations, which we have no idea about, and if the extra weight improves the performance in some areas more than it hinders it in others it gives more points. Not to say the system isn't buggy every now and then but there are actual physics calculations behind the results.
 
Physics is a multivariable thing.
Take this equation for acceleration, for example:

Acceleration = force/mass.

That tells you that if you increase the mass, the acceleration gets reduced, if the force remains the same.

However, a front engine rear wheel drive car often has a low proportion of mass on the rear axle, which limits the amount of traction during acceleration, so adding more mass to the rear of the car increases the traction and thus the force generated at the rear axle (especially at the lower gears where the wheel torque is at its maximum). If the increase in force is greater than the increase in mass, the net effect is improved acceleration. So in that case adding mass would be beneficial.

There was a rallycross driver in Sweden during the 70's and 80's who exploited this by filling the trunk of his car with gravel before the start of the race. That gave him better performance off the line. Then he dumped the gravel onto the track to make the car lighter for the rest of the race.
 
My question was more about the "strange" behaviour when adding ballast e.g.:

I add 15kg of ballast — my PP decreases.
I add another 1 kg of ballast — my PP increses.
A add anoither 1 kg of ballast — my PP decreases.

Is it OK that 16kg of ballast increases my PP when 15 and 17 kg decreses it?

Generally, as I gradually add Ballast, every now and then it happens that instead of the expected decrease in PP, it increases. And I have no idea if this is a bug or if it is correct and it happens in reality.

Same happens when gradually positioning the ballast forward or backwards. PP moves one direction (decreases) but in some cases it unexpectedly moves the opposite way but then starts moving the expected way again.
 
The most recent physics update, which was in January 2025 IIRC, made it less linear. It still follows the logic of reducing PP with more weight in the front and increasing it with more weight in the rear, but it's not as straightforward as before. Also, some cars are quite problematic and hard to nail a specific PP number with (which is a problem for my OCD self).
 
wlashack
Helllo,
I found that adding ballast does not affect PP as I would expect. You often find spots where adding another kg of ballast increases the PP which looks strange to me.
I am not a tuner so I ask - is this ok or is it a bug in gt7? Thanks.
Click to expand...

Is this happening on all your cars or just one or one group / type?

Could you post your settings sheet or let us know what car (and spec) you got this issue on?

I found similiar issue with the Porsche 962, but it was power, not ballast, also the PP system doesn't seem to recognise the benefit of different tyres fr to rr either.

Interesting to see this happening with ballast too... just wondered what car(s) you found it on..
 
I think it is happening on all cars. You can simply try it yourself:
Choose a car and buy Ballast for it. Don't change anything, just always add 1 kg of Ballast and measure the PP. You will see that after several measurements the PP does not decrease (as you would expect), but increases. And then it will decrease again, but after a while you will again come across a value at which the PP is higher than with the previous lower load.
The same thing happens if you do not change the ballast, but only move its location.

Example: Suzuki Swift Sport '07:
default PP: 405.13
Ballast 1kg: 404.91
Ballast 2kg: 404.43
Ballast 3kg: 404.71 kg
Ballast 4kg: 404.64 kg
…

I'm trying to figure out if this is okay and the same happens in real world (because there is some more complex physics at play here), or it is a bug or what is the reason that this is happening.
 
wlashack
I think it is happening on all cars. You can simply try it yourself:
Choose a car and buy Ballast for it. Don't change anything, just always add 1 kg of Ballast and measure the PP. You will see that after several measurements the PP does not decrease (as you would expect), but increases. And then it will decrease again, but after a while you will again come across a value at which the PP is higher than with the previous lower load.
The same thing happens if you do not change the ballast, but only move its location.

Example: Suzuki Swift Sport '07:
default PP: 405.13
Ballast 1kg: 404.91
Ballast 2kg: 404.43
Ballast 3kg: 404.71 kg
Ballast 4kg: 404.64 kg
…

I'm trying to figure out if this is okay and the same happens in real world (because there is some more complex physics at play here), or it is a bug or what is the reason that this is happening.
Click to expand...
OK, so you're adding 1kg of ballast in the stock position.

If you're looking for real life answers then can't help you, speak to Greycap or the others, but comparing GT to real life, hope you got a good supply of valium ready.

Yep, you're figures are correct, there is an increase, but being a bit more brutal with it i.e. 50kgs:

Stock 405.13pp
+50kgs 398.84pp (-6.29pp)
+100kgs 392.28pp (-6.56pp)
+150kgs 384.96pp (-7.32pp)
+200kgs 378.81pp (-6.81pp)

It's not 100% linear, but it does show a roughly general reduction.

The PP system is pretty bad on GT7, there's a few areas in tuning where it just doesn't make any sense at all. Not sure how you're going to re-create this in real life, but the others who replied know way more about that than me so they should be able to help.

Best of luck 👍
 
I need to experiment more with this but it seems ballast is added to the physical center of the car rather than its center of mass. This means position 0 isn't really position 0 from a dynamic POV, which means adding weight to position 0 may actually help performance.

Doesn't explain differences between adding 1 or 2 kg, though.
 

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