Three Hundred Miles Per Hour

  • Thread starter Thread starter Dark Elite
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Evolution.
Negatory.
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This is the main part why you didn't reach 300MPH. Odd as it may sound, and contradicting real-life rules, a spoiler aids greatly in GT4. Try it...

And I used the supercharger as well - 300MPH is also possible with the Turbo, though.
 
Gingiba
This is the main part why you didn't reach 300MPH. Odd as it may sound, and contradicting real-life rules, a spoiler aids greatly in GT4. Try it...

And I used the supercharger as well - 300MPH is also possible with the Turbo, though.
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Hmm...I'll have to try that. I have 292.21 so far with no wing and a turbo.

294.56 with no wing, and a supercharger. Argh.
 
Downforce is probably, for most cars, the single most influential aspect of 300mph tuning. It's also the simplest, so go and take advantage of it ;)

Just remember that anything you know to be true in real life is useless here :sly:

DE
 
Evolution.
So, in GT4, more downforce is better?

Oi!
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Odd, isn't it?

I've thought about it - why rear downforce and high front-ends are better. And here's my very wild theory: GT4 doesn't calculate drag/wind-resistance for the bottom of the car.
It sounds a little odd, even to me (seeing as it's my theory, I should at least believe in it), but I had to ask others about their thoughts: It seems to me like the bottom half of the car, in GT4, seems to be a 'dead space' - therefore, a high front-end increases the 'dead space' (extra downforce on the rear simply lifts the front some more by sinking the rear). My Idea goes like this:

300mphexplainwd1.jpg


This shows visibly how the 'surface' of the bottom, which, according to my theory, isn't calculated in the game, makes the size of the calculated part of the front much smaller - creating less friction/drag/digital slowdown, enabling the car to go faster.

I even suspect that if this theory is true, it explains the wheelie trick as well: A car with a wheelie that gets high enough is, theoretically, able to achieve infinite speeds as long as it has a sharp front-end, which results in the whole car being classified as "dead space" from the point of view of GT4 - it then creates 0 drag, theoretically able to go as fast as the gearbox enables it to go.


Sorry if it's a clutter, I tend to slide off the topic while explaining big stuff.
 
My thoughts exactly, really. Higher front end = less rear downforce, but more surface area on the bottom. In real life, it would be harder to find the sweet spot, but in GT4, you just drop your ass to the concrete and floor it.

ZOMG! 300.19 MPH!
 
Mostly when people consider how well GT4 high speed tuning compares to real life, they tend to consider that increasing downforce (thus increasing drag) should slow the car down. This is of course true, in both GT4 and real life. However, most people forget that increasing downforce can also increase traction through the driving wheels, which increases the effective driving throughput of the engine. Essentially it becomes a 2 way battle to increase the traction through the driving (rear) wheels, whilst at the same time trying to minimize drag. What I'm saying is that you cannot consider only one aspect of high speed tuning when making a comparison between GT4 and real life, as there are many factors that determine how fast a car will go.

When you consider this, the tuning approach you need to use is not actually as far from that you would use in real life as most people think. Take a look at the tuning techniques used by projects such as BAR Honda's 'Bonneville400' for a real world example of making a car go faster. :)
 
That is the most original explanation of GT4's oddball downforce physics I've seen, Gingiba. ;) MS' explanation is the more likely (and more real-world-possible) way of looking at it, but I personally think the change is too great to be simply traction-oriented.

DE
 
Dark Elite
That is the most original explanation of GT4's oddball downforce physics I've seen, Gingiba. ;) MS' explanation is the more likely (and more real-world-possible) way of looking at it, but I personally think the change is too great to be simply traction-oriented.

DE
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I know it's a little far off and overly wild... But that's my idea. It came after a bit of thinking how GT4 simply doesn't calculate the stuff it doesn't think is neccessary - and why the hell should someone, in the middle of the race, want to wheelie? Flippin, perhaps - but they disabled that for a reason...

But I agree, Traction can't be the explanation for a further 50MPH (at times)... And then, a higher front doesn't exactly grant better traction. Au contraire, it should reduce it. I found this article which supports what I suspected to happen to real-life cars which are similarily set up... Which also means the high-front should, rather than increase speeds, reduce it and let the car fly.

And DE, I'm currently working on a Viper for another entry in the club. I love overpowered big-engined FRs just as much as I like their low-power lightweight counterparts...
 
Gingiba
And then, a higher front doesn't exactly grant better traction. Au contraire, it should reduce it. I found this article which supports what I suspected to happen to real-life cars which are similarily set up... Which also means the high-front should, rather than increase speeds, reduce it and let the car fly.
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The higher front should should reduce the traction on the front wheels only, which is ideal as in a real wheel drive car they do not provide any driving power, and so any traction they provide acts as extra drag on the car.

An additional theory I've been considering is that due to the slant caused by the high front ride height, the gap between the underside of the car and the road will be smaller at the rear of the car. As such, air traveling under the car will need to travel faster at the rear of the car to fit the same volume of air through the narrower gap. Essentially, this is a very crude ground effects system, which would reduce air pressure underneath the car (due to the faster air speed, as per Bernoulli's principle) with a bias towards the rear wheels. This lower pressure causes an increase in downforce without producing additional drag, which further increases the traction at the driving wheels.
 
MasterStorm
The higher front should should reduce the traction on the front wheels only, which is ideal as in a real wheel drive car they do not provide any driving power, and so any traction they provide acts as extra drag on the car.

An additional theory I've been considering is that due to the slant caused by the high front ride height, the gap between the underside of the car and the road will be smaller at the rear of the car. As such, air traveling under the car will need to travel faster at the rear of the car to fit the same volume of air through the narrower gap. Essentially, this is a very crude ground effects system, which would reduce air pressure underneath the car (due to the faster air speed, as per Bernoulli's principle) with a bias towards the rear wheels. This lower pressure causes an increase in downforce without producing additional drag, which further increases the traction at the driving wheels.
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Yet, you see, if GT4 was smart enough to calculate that, it would also calculate that a car with a higher front will lift it, causing a flip - or at least a flight.

If we're taking Bernoulli into this, then again, this goes the opposite direction - a higher rear would create something like a vacuum, sucking the car onto the ground, and the whole car would function like a giant wing, generating slightly more downforce overall. Yet, this doesn't work in GT4...
 
Gingiba
Yet, you see, if GT4 was smart enough to calculate that, it would also calculate that a car with a higher front will lift it, causing a flip - or at least a flight.
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GT4 does work out that the front will lift, that's why we have the wheelie trick. The car won't flip because the game simply isn't coded to handle an upside down car. We're talking about the extreme fringes of the GT4 engine here, so it will certainly be a little rough in places. I don't know whether GT4 actually takes Bernoulli's principle into consideration or not or if the wheelie-ing is just emulated/caused via some other means, though I will admit that when I was typing my last post, I did wonder if it had been modeled or not.

Gingiba
If we're taking Bernoulli into this, then again, this goes the opposite direction - a higher rear would create something like a vacuum, sucking the car onto the ground, and the whole car would function like a giant wing, generating slightly more downforce overall. Yet, this doesn't work in GT4...
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I'm not quite sure what would happen in the case of a low front and high rear, though I suspect it's one of two situations. It could be that a partial vacuum will be created underneath the car (as air would not be entering the front at rapid enough a rate), leading to increased downforce. Alternatively, a body of air could form underneath the car, creating an area of high pressure which would act to push the car upwards. In both cases however, the shape of the car would be functioning as a wing, which would raise downforce, but also have massive drag (consequently reducing speed). I also think that in both cases a large amount of turbulence would occur at the front of the car, further adding to the drag problems.

As I said though, I'm not quite sure on that one. When it comes to aerodynamics, I think GT4 probably makes a few simplified calculations that lead to a passable/convincing result in the majority of cases. However, when your taking things to the extreme limits such as in 300mph+ tuning, there are bound to be numerous aerodynamic effects taking place which have been removed from the model due to their insignificance at lower speeds (or difficulty of implementation).

I'm not trying to make the claim that GT4's engine is perfect, far from it; rather I'm saying that the approach to high speed isn't as obvious as people think, and that you cannot simply say that GT4 is outright wrong because raising downforce increases speed. The traction/drag trade off applies to real life just as much as it does to GT4, but I doubt that anyone here knows quite how much a difference adjusting those factors makes in the real world. 👍
 
Gingiba
Rest assured, your record is way out of my league.
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It's always nice to hear that :p I think that particular record is out of everyone's league!

I shall just read the advanced physics analysis, rather than embarrass myself by attempting to contribute :)

DE
 
Hadn't really planned on doing anymore runs, but had a good read on the posts about downforce and LSD and tried again.

After changing settings on downforce (before i tried to keep it to a minimum) and the LSD, managed to get 358.64mph out of the Bentley Speed 8



http://www.youtube.com/watch?v=L5LW3HRahx8

sorry again for the rubbish quality, I'm basically pointing a digital camera at the tv that just happens to take videos. I'l try and sort a better replay out if I can
 
Nice improvement Pyrelli, I'll get that video watched and checked tonight 👍

Removed - dealt with :)

EDIT - OK, I can't see a hell of a lot in this video, not enough to be sure - can I have a second opinion from a 300mph Bentley driver on this one, please? Thanks.

DE
 
First of all i have no idea on what you guys are talking about. ( high downfor causes turbulence??????? Or whatever ya'll meant) But i'm going to try high downforece in the front and low in the back and vice versa. Then i will try to put high dowforce both front and back.
 
Hi all :D
Hope anyone here still remember me :)
Sorry for being away for a long time; I had lot´s of problems to solve, and my work was just taking all the time i used to have =\

Anyway, i´m back. So, hey DE, what´s the news?

I would like to know how You, Toronado, 2078TM, viperpilot, GT4_Rule and others are doing :) Miss you guys!

And about the records.. i will check how the leaderboard is right now :)

I will try the Rx-8 again, (i have to start all the math-gt4 again, i think i lost my settings notations LOL). But i think i still know how to do it :)

Nice to have time to see the old friends again :D
I will be back soon, hope to bring you new records :D

Cheers
 
Hi there Ichi! It's been a while 👍

So far as I know, you've not missed much - a few new members, a few contested speeds, and that's it really. Also, an adjustment to the rules involving hybrids.

Good luck with the RX-8, and let us know how it goes :)

DE
 
Id like to intro myself, I have been playing GT4 for over a year now.. And, I have finally made it over the 300+ mark. Here's my proof....

digicam069.jpg


sorry for the crappy picture
 
Dark Elite
Hi there Ichi! It's been a while 👍

So far as I know, you've not missed much - a few new members, a few contested speeds, and that's it really. Also, an adjustment to the rules involving hybrids.

Good luck with the RX-8, and let us know how it goes :)

DE
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Thankyou DE! I was out for a really long time (at least for me ^^), and i´m glad to come back. Now i´m like a crazy searching for my notations, (i really don´t want to lose my gears settings x] ), and there is always my old rx-8 in the save, and i think he still got the old configuration of the record, as i don´t use it to any competition (When i need another rx-8 i use the rx-8 concept from the license test :D) So, new tests and Benchmarking will start today when i got home :)

Nice to know that i have not missed too much. Welcome to the new members, congrats to all the new speeds in the leaderboard! Also, whats the change in the rules? :D

Ps: Omg i´m still the fastest Vertigo? I think i should Quote 2078TM.

Please anyone give me a reason to take my Vertigo out of the garage! ^^

And 2078TM, i will try to catch you speed, but i think it will be a pretty hard job.. i wonder if it is possible :X

Nice to see you again, DE. \o\

Cheers
 

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