Top Speed Parameters; interesting results! - Now with summary

  • Thread starter Morphisor
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frontrunner91
Actually years ago Nascar teams used ultra soft rear suspension to drop the rear spoiler out of the air to get more speed out of the cars. Nascar now assigns the teams the rear springs and shocks they use at superspeedways.

Gt5 is not the 1st game that favors the tail down nose up chassis settings. I've been doing this for a long time. Papyrus Nascar games allowed this method as well. The venerable Nascar 2003 AKA the game that is the basis of I-Racing (66% of the code IIRC is the same) allowed the tail dragging set ups.
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^^ This is correct. A lot of you might remember a long while back when F1 drivers could hit a button which lowered the rear suspension and thus decreasing the downforce from the rear wing. This gave them a higher top speed in the straights. Which brings me to the following:

From what I can gather from the OP's data, everything sounds about right except for the downforce part. Taking a look at the top speed data and the downforce settings, it would appear that GT5 takes into consideration the frontal cross section of the car but not the rear wing drag when it comes to top speed. Minimizing the front wing and maximizing the rear wing shouldn't result in such a higher top speed.
 
Disavowed
^^ This is correct. A lot of you might remember a long while back when F1 drivers could hit a button which lowered the rear suspension and thus decreasing the downforce from the rear wing. This gave them a higher top speed in the straights. Which brings me to the following:

From what I can gather from the OP's data, everything sounds about right except for the downforce part. Taking a look at the top speed data and the downforce settings, it would appear that GT5 takes into consideration the frontal cross section of the car but not the rear wing drag when it comes to top speed. Minimizing the front wing and maximizing the rear wing shouldn't result in such a higher top speed.
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The thing is, with a 'normal' suspension setup, it doesn't! Although admittedly the negative effect of the rear downforce is FAR too low, the car was slower that way. It was only when I later discovered that the ride height has such a huge influence that I tried the two together....to get that crazy result.
 
Morphisor-
Good job mate 👍
I thought grippier tyres meant slightly less top speed due to friction too and also assumed that a lower car would be faster due to decreased wind resistance.
Although the downforce is shown to make a difference I still think that on a normal race track it would be pointless to remove DF for the tiny increase your test has shown, I think the effect should be more profound.
 
Morphisor
As you can see, the tires with the most grip are the best.
Now, I am not exactly an expert on physics, but I was under the impression that tires with a lot of grip should actually negatively affect top speed because of the increased friction... Anyone?
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For horse carts, more grippy tires means lower top speed.
For cars, more grippy tires means higher top speed.

Hope you understand what I mean. If not, think about why sprinters wear grippy spiked shoes and not slippery glass shoes.
 
berty1979
Morphisor-
Good job mate 👍
I thought grippier tyres meant slightly less top speed due to friction too and also assumed that a lower car would be faster due to decreased wind resistance.
Although the downforce is shown to make a difference I still think that on a normal race track it would be pointless to remove DF for the tiny increase your test has shown, I think the effect should be more profound.
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I always believe it was the opposite, a higher car would be faster. The coss-sectional area of the car is the same (baiscally) but with a large width under the car, the air can flow less turbulently, reducing drag.

I think the Veyron in max speed mode lifts the car slightly.
 
Regarding the nose-up effect: It's actually about aerodynamics and not suspension. The bug in GT is how the downforce is applied, which is 90° to the cars bottom plate and not simply down to the track. So with nose up downforce pulls the car forward and not only down. You can prove this by testing a nose-up setup with different downforce levels. The higher the downforce, the faster the car can go. On the other hand cars without noticeable downforce don't see any advantage from nose-up at all.

Thanks for running those tests, OP! The car-wash result is quite a surprise to me.
 
vramak
For horse carts, more grippy tires means lower top speed.
For cars, more grippy tires means higher top speed.

Hope you understand what I mean. If not, think about why sprinters wear grippy spiked shoes and not slippery glass shoes.
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I disagree. Having been a sprinter myself for some years, I can tell you that the spikes are there to provide maximum grip at pushing off. Because humans, when running, do not have a constant power output, but instead pulses (feet hitting the ground and pushing off again), it cannot be compared to cars.

For cars, high grip tires are very important in getting off the line, because that is when the tires have loads of torque to process in an instant.
However, once grip is established, there is no longer the need for maximum grip to keep increasing speed.

Soft tires provide more traction, which is caused by their providing more friction with the road surface. Now any physicist can tell you that friction is the most important factor that influences an object's speed, negatively.
Hard tires may give you a bad start, they will roll harder in the end.

...At least, in the real world :indiff:
 
- Given the same tread pattern and tire size, hard tires will have less rolling resistance than soft tires.
- Treaded tires, given the same grip, have more rolling resistance than slick tires.
- Cheap "energy saving" street tires (for example Comfort Hard) should have less rolling resistance than sporty summer tires (for example Comfort Soft), for both differences in tread pattern and softness.

However, I don't know the differences in rolling resistance between typical street tires, semi-slick tires and slick tires of the same size. This is the hard part to determine.
 
Hi Everyone. GREAT POST :)

(forgot to mention that I don´t speak english as my native language. Please understand sure mistakes :D )

Let me add a couple of things to the discussion. (But the most important is point 4)

1) Lower ride height AFFECTS Top Speed IRL. Take, for example, the Veyron and its Special Top Speed Key

2) Aerodynamics do the same with Top Speed. And again, you have the example with the Veyron.

3) Sticky Tires do not add drag. Quite the opposite. At extremely high speed you need a lot of grip to avoid the tire sliding. What add LOTS of drag are wide tires. But you can´t modify that setting in GT5.

4) GT5 DOES NOT PROCESS FLUIDS. (And the "air" its a fluid, after all). Its as simple as that. I remember reading and interview to Kaz in wich he specifically mentioned that FLUID PROCESSING was out of GT5 because of limitations in the PS3 (or any actual console out there). If I remember correctly (pretty limited internet here at work) it was after his time developing X-2010 in Red Bull HQ and testing its F1 simulator.

So, without fluid calculations, drag/wind/ground effect just do not exist as a factor that could be simulated in any way but with fixed parameters. And that why suspensions work in really strange ways doing those speed tests. I remember too the CLK-GTR flying in LeMans, and that won´t happen in GT5 because there is no "real" air in the track.

Bye !

pd. I´ll try to find the interview. It was here, on GtPlanet.

Astro_BS-AS
 
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I remember during the Alesi and Berger years Ferrari was waxing their cars at monza to gain a mile per hour, this was really a dark period for ferrari lol.
 
vramak
You should probably read up more about tire physics. I'm sorry, I'm too busy with work now to explain why you're wrong.
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You definitely need to explain why grip helps you get from 250mph to 260mph easier than reduced friction does.
 
Imari
You definitely need to explain why grip helps you get from 250mph to 260mph easier than reduced friction does.
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If its a RWD car then the front tires are pushed and I would assume the less friction/grip the better.

The rear tires are potentially trying to go faster than the track beneath them because they are the driving tires. Grip would be more benifitial here I would imagine.

If the less grip to go faster is correct. Then surely on a straight the tires when at there most worn out would be faster but hopeless round a corner obviously.
 
The faster you go the thicker the air effectively becomes requiring more grip to allow the car to be pushed faster through the air. If you fitted hard commuter style tyres to a Bugatti veyron it would start to spin the wheels as the speed increased. That's why the tyres fitted to the veyron cost 25,000 USD per set and would only last for 37 miles at full speed.
 
Cyber_stig_77
The faster you go the thicker the air effectively becomes requiring more grip to allow the car to be pushed faster through the air. If you fitted hard commuter style tyres to a Bugatti veyron it would start to spin the wheels as the speed increased. That's why the tyres fitted to the veyron cost 25,000 USD per set and would only last for 37 miles at full speed.
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That does sound plausible. Like I said before, I'm by no means an expert...so if anyone with more insight into the physics could explain this thoroughly..

Clearly there is still much confusion about this.
 
vramak
You should probably read up more about tire physics. I'm sorry, I'm too busy with work now to explain why you're wrong.
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Which is good, because he isn't. Rolling resistance has a much lower effect than air resistance (because it increases more-or-less linearly and air resistance increases exponentially), but lower rolling resistance still translates to a higher top speed because it still increases as the speeds increase.

dadn
I always believe it was the opposite, a higher car would be faster. The coss-sectional area of the car is the same (baiscally) but with a large width under the car, the air can flow less turbulently, reducing drag.

I think the Veyron in max speed mode lifts the car slightly.
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A lower car has a lower frontal area. Lower frontal area has a dramatic effect on wind resistance.


And a Veyron in top speed mode is lower to the ground than a Veyron in any other mode.

Cyber_stig_77
The faster you go the thicker the air effectively becomes requiring more grip to allow the car to be pushed faster through the air. If you fitted hard commuter style tyres to a Bugatti veyron it would start to spin the wheels as the speed increased.
Click to expand...

That's absurd. Wind resistance would never get high enough at the speeds performed in the game where the tires would start to spin because of (among other things) torque reduction in the gearbox. If a car won't spin the tires from a hard launch in 7th gear, it won't spin the tires going 270 (or whatever) MPH in 7th gear. If wind resistance became so great that it overcame the forward momentum of the car, nothing more would happen other than the car no longer accelerating.

The tires on the Veyron cost so much because they were custom-built to go the speeds the Veyron can while supporting the Veyron's weight at low speeds and still being tractable as normal street tires.
 
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ugabugaz
OFFLINE ONLY. Take a look at the Top Speed thread. I hold nearly all High end car Top Speeds. I think I know what I'm doing. When I'm telling you it's specific, that's it. Whether or not you want to believe me is of your own accord. Also, different tracks and cars do things slightly differently. In any case, match any of my recorded speeds on SSR7 with minimum downforce, and see how far you get.

I'm just trying to make sure GTP Users don't get the wrong information. I'm not going to reveal my settings as obviously it took quite some time to figure it out, but I did, so can you too. Experimentation is key.
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If you don't want users to get the wrong information then post your settings. If you don't want to post them then why say anything at all?
 
Toronado
That's absurd. Wind resistance would never get high enough at the speeds performed in the game where the tires would start to spin because of (among other things) torque reduction in the gearbox. If a car won't spin the tires from a hard launch in 7th gear, it won't spin the tires going 270 (or whatever) MPH in 7th gear. If wind resistance became so great that it overcame the forward momentum of the car, nothing more would happen other than the car no longer accelerating.

The tires on the Veyron cost so much because they were custom-built to go the speeds the Veyron can while supporting the Veyron's weight at low speeds and still being tractable as normal street tires.[/color][/b][/font]
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Hi ! I´ll "quote myself"

4) GT5 DOES NOT PROCESS FLUIDS. (And the "air" its a fluid, after all). Its as simple as that. I remember reading and interview to Kaz in wich he specifically mentioned that FLUID PROCESSING was out of GT5 because of limitations in the PS3 (or any actual console out there). If I remember correctly (pretty limited internet here at work) it was after his time developing X-2010 in Red Bull HQ and testing its F1 simulator.

So, without fluid calculations, drag/wind/ground effect just do not exist as a factor that could be simulated in any way but with fixed parameters. And that why suspensions work in really strange ways doing those speed tests. I remember too the CLK-GTR flying in LeMans, and that won´t happen in GT5 because there is no "real" air in the track.

Bye !
 
Thank you for your tests, may you please test top speed, with Ballast, say 25-50kg increments, Front, Mid, and Rear pos?
 
Below is a new section that I have added to the main post as well. See for yourself...

-------------------------

I have conducted a set of tests with a different car to find out just how influential downforce really is. The car of my tests so far has levels of downforce higher than roadcars even in minimum trim after all.

The new test car is the Toyota 86 GT '12, fully modded. Transmission set to 340, suspension set to standard settings (without the standard rear toe however).

First test subject was the difference between full downforce (0/20) and minimal downforce (0/5).
At either downforce level I achieved a speed of 297.6 km/h!
The effect of downforce on roadcars' top speed is absolutely minimal it seems.

Next up was to find out if the ride height mystery could be applied to this car as well.
I put downforce back to it's minimum of 5 for now.

First I lowered the spring rates to their minimum, and did a run. No difference in speed.

Now comes the part where I tested several ride height combinations, starting with the minimal -20 on both ends:

-20/-20: 297.6
0/-20: 297.6
+20/-20: 297.8
+45/-20: 297.9

Astonishing, huh? A car on which the downforce failed to influence the top speed enough to make a measurable difference gains 0.3 km/h from a completely ridiculous suspension setup.

Let's see if adding the downforce back in now will add to this madness though...
Why yes it does! Speed was increased to 298.7 km/h!!!


This is conclusive evidence that GT5's suspension system is fundamentally flawed.
And while downforce is not the cause of the problem, it DOES add to it after the suspension has been abused.

edit: this car was tested using SS tires
 
Toronado
Rolling resistance has a much lower effect than air resistance (because it increases more-or-less linearly and air resistance increases exponentially), but lower rolling resistance still translates to a higher top speed because it still increases as the speeds increase.
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That's correct. But the thing is, grippier tires don't have more rolling resistance; they have more sliding friction.

About the relation between grippier tyres and top speed - grippier tyres slide less, thus more power is put down to the ground. This means less wheelspin/wheelslip and hence more acceleration. Top speed is a result of prolonged acceleration. So, grippier tyres will result in better top speed.

That's all I have to say. If you think I'm wrong, I don't care.
 
Lambob
Thank you for your tests, may you please test top speed, with Ballast, say 25-50kg increments, Front, Mid, and Rear pos?
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Oh, good call.
I will have to do some testing with this in both a 'normal' setup and a 'trick' setup, seeing as how the trick setup uses very odd ride heights that definitely affect weight balance.
 
vramak
That's correct. But the thing is, grippier tires don't have more rolling resistance; they have more sliding friction.
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Is there not a direct correlation between the two? I recognize that modern low rolling resistance tires offset the effect somewhat with their extensive use of silica, but why would what basically amounts to qualifying spec tires be the same way?
 
Am I the only one not surprised, that a higher front end results in fastest top speed in a straight line? I mean, the weight is being offloaded at an angle toward the rear, so the rear has less to "push" travelling in that straight line, am I wrong? Of course, if wind resistance was working, we'd probably have lots of front end drag. I wonder if PD modeled the 2 wheeled Segway as a supercar, that would be the fastest machine in the game, lol.
 
I just did some quick testing, but I got strange results...

I wanted to test the new Aventador against the Enzo Ferrari.

First thing I noticed, eventhough the Aventador has stock more HP than a Enzo (I bought a new one for this test, both cars got oil changes), the Enzo has a little bit more power after max tuning it. I wonder why :?

Then I started the test, I didnt changed the LSD/suspension, both cars have no aero mods, both gear boxes are set to 450km/h.
Ok, the Aventador beats the Enzo to 100km/h easily, but at +250km/h things get weird. Both cars have more or less similar power output (both power/rpm/torque graphs look same), but the Aventador barely reaches 395km/h while the Enzo gets up to 420km/h.

Can anybody explain to me why this is happening? I cant imagine the drag difference between both cars being that big.
 
Cyber_stig_77
The faster you go the thicker the air effectively becomes requiring more grip to allow the car to be pushed faster through the air. If you fitted hard commuter style tyres to a Bugatti veyron it would start to spin the wheels as the speed increased. That's why the tyres fitted to the veyron cost 25,000 USD per set and would only last for 37 miles at full speed.
Click to expand...

Yesterday i was racing on X Route with TVR Speed 12, and i was surprised why my rear tyres were so worn after a half lap. I though it was because Toe/camber setting, but this sounds more likely. Toe, neither camber were not set to extreme (max) settings.
Race was with Race Softs and no Aero, otherwise full tuned. Top speed in slipstream 303 mph. Without i can't remember correctly, it was about 270 mph.

I wonder if higher downforce, or any other setting do worse fuel consumption
 
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DaveTheStalker
Mythbusters have proven that a dirty car is faster...

(PD needs to step up their game ;) )
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True. The tiny bumps disrupt and prevent the boundary layer friction. That's why fighter jets are not shiny, more like primmer, rough surface equals less drag. Which makes me wonder why Indy car teams dont just primmer their cars to get higher top speeds.
 
The loss of top speed due to the car being dirty might be the simulated effect of clogged filters, intake, etc. (I would expect the loss to be higher however).
 

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