Forza 4 vs GT5 physics (read the first post before contributing)

[amar212]

All of which is an aside because the techniques required to get a top time in the GTA were simply people taking advantage of the issues that exist within GT5/GTA's physics engine.

Exactly, I agree on this 100%.

Simply put, while in Forza drifting actually slows you down, in GT you can maintain speed while drifting. Which is not right by any mean.

 

[Ridox2JZGTE]

Did the car actually gain more speed while sliding in GTA ? I often slides my car around corner exits from time to time in GT5, but rarely I've seen my car carry more speed while sliding or gain more time while doing it. What sort of slides is it ? The kind that Formula 1 car have around tight corners ? or slides that leaves black tire marks ...

I always thought that engine braking is only used to help controlling the car speed on a steep slope, and I am referring to smooth surfaced road here, brake alone would not be sufficient in some cases, as they get overheated and faded on a long way down from a hilly road. I have a bad experience once while still learning to drive 15 years ago, I went down hill while still on 2nd gear, tried to brake with the engine by shifting to 1st, the car over revs, silly me not looking at my terminal speed on 2nd. The car was still going at the speed it has before going to 1st even when the engine could not rev higher, thankfully I still have a brake to slow the car down.

Off road/ 4WD cars with hill descent features are using computer controlled brakes and other electronic stuff to help control the speed while descending, they have better lower differential gears than normal cars. So maybe not all cars would go faster on down hill with engine braking and no brakes at all.

 

[Argon]

I've been a hardcore fan of both Forza and GT franchises from release one of each and have played each to the maximum and they are very different games even though driving is the common theme.

I'm not even sure that a direct comparison is even fair or just. The latest incarnation of each game are so good yet different that it's no wonder opinions will be polarised. For my part though;

GT5 is a near realistic simulator that requires an understanding of actual driving and real life physics to get the most out of the game.

Forza is a fantastically realistic arcade that require an understanding of how the game works to get the most out of the game.

My simple test is to drive broadly the same car around the same circuit in both games and the lap times in the two games don't really compare although those in GT5 are nearest to actual reality. (based purely on my marginal skills)

I love both games and would never choose one over the other as they are both great games that reward the player in equal amounts for pulling off that perfect lap, overtake or whatever is your thing. As to the vote, I have to go with GT5 but that is absolutely not a slap down for Forza in any way shape or form.

Major kudos to PD and Turn 10 for giving me over 15 years of great gaming fun, now where do I apply for the old age pensioner licence?

 

[hennessey86]

All of which is an aside because the techniques required to get a top time in the GTA were simply people taking advantage of the issues that exist within GT5/GTA's physics engine.

exactly scaff, GT5 physics were shown up fr what they really are in GT academy. Forza 4 is more realistic in my opinion, but you will never convince the loyal GT fan of this.

 

[hennessey86]

I've been a hardcore fan of both Forza and GT franchises from release one of each and have played each to the maximum and they are very different games even though driving is the common theme.

I'm not even sure that a direct comparison is even fair or just. The latest incarnation of each game are so good yet different that it's no wonder opinions will be polarised. For my part though;

GT5 is a near realistic simulator that requires an understanding of actual driving and real life physics to get the most out of the game.

Forza is a fantastically realistic arcade that require an understanding of how the game works to get the most out of the game.

My simple test is to drive broadly the same car around the same circuit in both games and the lap times in the two games don't really compare although those in GT5 are nearest to actual reality. (based purely on my marginal skills)

I love both games and would never choose one over the other as they are both great games that reward the player in equal amounts for pulling off that perfect lap, overtake or whatever is your thing. As to the vote, I have to go with GT5 but that is absolutely not a slap down for Forza in any way shape or form.

Major kudos to PD and Turn 10 for giving me over 15 years of great gaming fun, now where do I apply for the old age pensioner licence?

what do you drive both with a wheel or pad

 

[Argon]

what do you drive both with a wheel or pad

Pad on both

 

[Scaff]

Did the car actually gain more speed while sliding in GTA ? I often slides my car around corner exits from time to time in GT5, but rarely I've seen my car carry more speed while sliding or gain more time while doing it. What sort of slides is it ? The kind that Formula 1 car have around tight corners ? or slides that leaves black tire marks ...

Its not that you gain speed when traction is lost in GT5/GTA its that you don't lose any.

The moment you exceed the limit on rubber when cornering you lose lateral grip and therefore speed (often referred to as tyre scrub), this simply doesn't happen in GT5/GTA.

Take a look at footage from any tarmac event, be it F1, DTM, WRC tarmac stages and you will see they do everything they can to keep the tyres right on the very limit of grip, because a fraction over in either direction is slower.

I always thought that engine braking is only used to help controlling the car speed on a steep slope, and I am referring to smooth surfaced road here, brake alone would not be sufficient in some cases, as they get overheated and faded on a long way down from a hilly road. I have a bad experience once while still learning to drive 15 years ago, I went down hill while still on 2nd gear, tried to brake with the engine by shifting to 1st, the car over revs, silly me not looking at my terminal speed on 2nd. The car was still going at the speed it has before going to 1st even when the engine could not rev higher, thankfully I still have a brake to slow the car down.

You can use compression braking on almost any descent and on any surface, I've used it on a 14 degree slope on a public road on the back road near my home and its perfectly possible to control the entire descent with the engine alone.

The situation you describe above sounds a lot more like a misjudgement on your part, which doesn't in itself mean the practice is invalid, simply that (in this case) you did not apply it correctly.

I would guess that had you started the descent in 1st gear you would have been able to control it with engine speed alone.

Off road/ 4WD cars with hill descent features are using computer controlled brakes and other electronic stuff to help control the speed while descending, they have better lower differential gears than normal cars. So maybe not all cars would go faster on down hill with engine braking and no brakes at all.

I'm talking about cars without these systems, the majority of my own off-road experience is in a Series II Land Rover, which has zero electronic aids of any sort. Pop that in 1st and Low Range and you don't need anything else for a controlled descent.

GT5 is a near realistic simulator that requires an understanding of actual driving and real life physics to get the most out of the game.

Forza is a fantastically realistic arcade that require an understanding of how the game works to get the most out of the game.

Totally and 100% disagree.

Swap those around and you would have my view on it (apart from neither being a near realistic sim), GT5's lack of a true tyre model and its very basic suspension modelling just doesn't cut the mustard in this day and age at all.

My simple test is to drive broadly the same car around the same circuit in both games and the lap times in the two games don't really compare although those in GT5 are nearest to actual reality. (based purely on my marginal skills)

I can't agree that lap times are a good indicator of how accurate a sim is at all, too many variable exists for them to be of any use at all. You could have a physics model that provides far too much longitudinal grip and far too little lateral grip, with them balancing out over the course of a lap. The lap time would be fine, but all that would do would be to hide the two clearly inaccurate parts of the physics model.

 

[Ridox2JZGTE]

You can use compression braking on almost any descent and on any surface, I've used it on a 14 degree slope on a public road on the back road near my home and its perfectly possible to control the entire descent with the engine alone.

The situation you describe above sounds a lot more like a misjudgement on your part, which doesn't in itself mean the practice is invalid, simply that (in this case) you did not apply it correctly.

I would guess that had you started the descent in 1st gear you would have been able to control it with engine speed alone.

Then do you agree if in the case of the example shown by previous poster Nismo34
"Go down a hill flat out in a samba bus in the highest gear then drop it back to first without using the brake.. What happens next? Yes, it gains speed... This wouldnt happen if it had engine braking... "

Never tried it before in GT5, but in real life going flat out down hill in fourth, then immediately shift to 1st without braking, the car would not have slowed down at all, it might even gain speed do to the steepness of the slope. Obviously the car would have engine damage, transmission damage or a crash, now that's not a problem in GT5

 

[Argon]

Its not that you gain speed when traction is lost in GT5/GTA its that you don't lose any.

The moment you exceed the limit on rubber when cornering you lose lateral grip and therefore speed (often referred to as tyre scrub), this simply doesn't happen in GT5/GTA.

Take a look at footage from any tarmac event, be it F1, DTM, WRC tarmac stages and you will see they do everything they can to keep the tyres right on the very limit of grip, because a fraction over in either direction is slower.



You can use compression braking on almost any descent and on any surface, I've used it on a 14 degree slope on a public road on the back road near my home and its perfectly possible to control the entire descent with the engine alone.

The situation you describe above sounds a lot more like a misjudgement on your part, which doesn't in itself mean the practice is invalid, simply that (in this case) you did not apply it correctly.

I would guess that had you started the descent in 1st gear you would have been able to control it with engine speed alone.



I'm talking about cars without these systems, the majority of my own off-road experience is in a Series II Land Rover, which has zero electronic aids of any sort. Pop that in 1st and Low Range and you don't need anything else for a controlled descent.




Totally and 100% disagree.

Swap those around and you would have my view on it (apart from neither being a near realistic sim), GT5's lack of a true tyre model and its very basic suspension modelling just doesn't cut the mustard in this day and age at all.




I can't agree that lap times are a good indicator of how accurate a sim is at all, too many variable exists for them to be of any use at all. You could have a physics model that provides far too much longitudinal grip and far too little lateral grip, with them balancing out over the course of a lap. The lap time would be fine, but all that would do would be to hide the two clearly inaccurate parts of the physics model.

It's true that using the technology available to us today that nothing is going to be truly realistic. I really do appreciate and totally respect your view but will stick with my perspective only because I think that whilst your arguments are valid when you look at specific aspects of the physics engine for me it's the total or overall effect I get and for me it just seems more life-like in GT5.

 

[Scaff]

Then do you agree if in the case of the example shown by previous poster Nismo34
"Go down a hill flat out in a samba bus in the highest gear then drop it back to first without using the brake.. What happens next? Yes, it gains speed... This wouldnt happen if it had engine braking... "

Never tried it before in GT5, but in real life going flat out down hill in fourth, then immediately shift to 1st without braking, the car would not have slowed down at all, it might even gain speed do to the steepness of the slope. Obviously the car would have engine damage, transmission damage or a crash, now that's not a problem in GT5

It most certainly would have slowed down. As well as encountered massive amounts of drivetrain shunt and damage. Quite possibly it would also have lost grip at the driven wheels as it could well exceed the slip limit of the tyres when the rotation speed of the tyres encountered a massive difference when compared to the forward direction of the car.

Testing for engine braking is actually quite straightforward, I did it in GT4 which does have engine braking......

https://www.gtplanet.net/forum/showpost.php?p=1794405&postcount=375


....in the same thread which covers why traction can be lost as a result of it (and why its not really a track driving technique).....

https://www.gtplanet.net/forum/showpost.php?p=1785601&postcount=361


.....have a read of the last one of those and you will (I hope) quite clearly see that if you drop from 4th gear to 1st gear in a real car you will most certainly be slowing down and doing so very quickly and with a good chance of engine and drivetrain damage and a good dollop of traction loss. At which point you may well start to gain speed but that's not as a result of the compression braking but a result of the loss of traction and sheer foolishness for doing it in the first place.

 

[sik180sx]

Right... Next GT5 has an accurate tyre model... No way GT5 has engine braking.. Go down a hill flat out in a samba bus in the highest gear then drop it back to first without using the brake.. What happens next? Yes, it gains speed... This wouldnt happen if it had engine braking...

Regardless of a realistic tyre model or not,when you use the clutch in gt5 there is engine braking.

 

[Ridox2JZGTE]

Thanks Scaff for the links, good reading

 

[Nismo34]

Want to prove it, try it yourself, find a hill, roll the car down without brake, use the engine braking and see what happens, but don't blame anyone if you crash. And an advice, never use higher gear when rolling down the hill, change to lower gear before rolling down, it's common sense.

I use the engine to slow myself down every day going down hills... Especially when Im doing a leisure lap of Mount Panorama on my Bike... The bike doesnt gain speed, it loses it. Why dont you try it? Going around a corner, Down shifting aggressively can cause the back to step out and lose traction, Forza also does this, does GT5? Nope...

When it comes to Forza V GT5 when it comes to engine braking, until someone can show me a lock up caused by down shift in GT5, Forza wins and Engine brake doesnt exist in GT5..

 

[Odyofil]

I use a clutch and there is definately engine brake in gt5.If i'm in 4th and i shift to 1st,hello compression lock-up.

Can you record a video please, theres no compression lock up in DS3, and there is no video that claims theres a engine break, i mean, go 200 kmh, and shift down to 2 or 1... please record.

 

[Christhedude]

Very, very rarely is it a quicker way around a corner, certainly on a race track its almost never quicker that maximising the last shred of grip a tyre has available.

Now while Tsuchiya did throw in a little drifting in his JGTC days it was mainly showboating when he was well ahead of the rest of the pack, its quite doubtful that he won as a result of it at all. He did also say:

"I drift not because it is a quicker way around a corner but the most exciting way."

All of which is an aside because the techniques required to get a top time in the GTA were simply people taking advantage of the issues that exist within GT5/GTA's physics engine.

exactly, even in the so highly praised iRacing simulator people slide their cars around turns without speed - time loss. Especially in the 120 minutes of thunder iRacing race i watched the pole sitters time and spoke to him regarding setup... he told me he was running 54 - 46 % brake balance which in real life is unable to be driven fast on tarmac / road courses.

Just like in GT5 people run 6-9 brake balance in order to rotate around entering turns.

As a matter of fact i have tried adjusting the brake balance in a Porsche GT3 Cup as far back as possible, and trust me when i tell you that the car was unable to be driven at qualifying pace !!!

Chris

 

[Scaff]

It's true that using the technology available to us today that nothing is going to be truly realistic. I really do appreciate and totally respect your view but will stick with my perspective only because I think that whilst your arguments are valid when you look at specific aspects of the physics engine for me it's the total or overall effect I get and for me it just seems more life-like in GT5.

The same for me with FM4, its a more accurate package overall in terms of physics, GT5 just has a disconnect between the driver and the road in terms of communication of grip that simply doesn't gel with how the real world works. FM4 is certainly not perfect in this regard, but its a lot closer than GT5 and as a result, for me, feels and communicates as a car should.

 

[Argon]

The same for me with FM4, its a more accurate package overall in terms of physics, GT5 just has a disconnect between the driver and the road in terms of communication of grip that simply doesn't gel with how the real world works. FM4 is certainly not perfect in this regard, but its a lot closer than GT5 and as a result, for me, feels and communicates as a car should.

If it's of any consolation, if you held a gun to my head and asked me to choose one to keep I'd have to go with Forza.

Respect to you Scaff, you've posted some great responses in this thread

 

[Saidur_Ali]

exactly scaff, GT5 physics were shown up fr what they really are in GT academy. Forza 4 is more realistic in my opinion, but you will never convince the loyal GT fan of this.

Most games / simulators will be "shown" up in such a situation. Loyal GT fan, there are loyal Forza fans too you know?

Its not that you gain speed when traction is lost in GT5/GTA its that you don't lose any.

The moment you exceed the limit on rubber when cornering you lose lateral grip and therefore speed (often referred to as tyre scrub), this simply doesn't happen in GT5/GTA.

You lose speed when sliding, but the trick is to maintain traction as much as possible. Being able to rotate the car on entry and power out early is the quickest way and is a technique used in real life, just not to the extent that can be done with the tyres in GT5.

exactly, even in the so highly praised iRacing simulator people slide their cars around turns without speed - time loss. Especially in the 120 minutes of thunder iRacing race i watched the pole sitters time and spoke to him regarding setup... he told me he was running 54 - 46 % brake balance which in real life is unable to be driven fast on tarmac / road courses.

Just like in GT5 people run 6-9 brake balance in order to rotate around entering turns.

As a matter of fact i have tried adjusting the brake balance in a Porsche GT3 Cup as far back as possible, and trust me when i tell you that the car was unable to be driven at qualifying pace !!!

Chris

Common thing in most sims, quickest way usually is the way to quicken weight transfer whilst maintaining traction through gear changes, brakes, throttle, or quick changes of direction with steering.

Ideal setup in real world for qualifying would be some controllable oversteer on entry of low speed corners so you can power out early and and for mid or high speed to be stable as possible without too much understeer. I guess you choose a setup more for endurance though so a more understeer setup is probably the one you use. I bet it feels good when you hit the sweet spot in the Porsche GT3 Cup car .

 

[Scaff]

You lose speed when sliding,

Yes because you have exceeded the slip limit of the tyre

but the trick is to maintain traction as much as possible.

But you can't do that if you've exceeded the slip limit!!!

Your two statements here contradict each other.

While you still have tractive force at small degrees of slip (and this is the place you will find the last bit of it) once you exceed that limit and are losing speed then you are not maintaining as much traction as possible.

I'm sorry to be a bit blunt but what you have just stated doesn't makes sense at all.

Being able to rotate the car on entry and power out early is the quickest way and is a technique used in real life, just not to the extent that can be done with the tyres in GT5.

You are talking about two totally different things here, what is happening in GT5/GTA has nothing at all to do with cornering while at the limit of grip. Yes cars rotate, but that has a limit and once you go above it your tyres (some or all) are past the limit and you should be losing speed not maintaining it. What is occurring in GT5/GTA is exceeding the limit of grip (and yaw) and not suffering in the form of a loss of speed, which doesn't occur in the real world because it defies the laws of physics.

Ideal setup in real world for qualifying would be some controllable oversteer on entry of low speed corners so you can power out early and and for mid or high speed to be stable as possible without too much understeer. I guess you choose a setup more for endurance though so a more understeer setup is probably the one you use. I bet it feels good when you hit the sweet spot in the Porsche GT3 Cup car .

Seriously I will let Christhedude handle this as a car is set-up for the driver, you don't have an 'ideal' blanket set-up and as such he is best placed to describe how he would want a car set-up.

However if you are trying to imply that 54 - 56% brake bias is drivable on the track then quite frankly you are well off base, as has been said that is simply not usable in the real world, yet in GT5 is perfectly fine because you don't get the loss of speed from the constant oversteer it throws at you.

 

[Kent]

It would make sense that without a clutch there is no noticeable engine braking but that's only because you are constantly doing it if not on the gas. As someone mentioned earlier, engine braking really isn't a track technique, it's a daily driving technique (if you drive a manual clutch).

 

[Ridox2JZGTE]

The rear brake bias in GT5 that people talk about here is surely used with brake assist enabled right ? Because I never drive in GT5 and GTA with brake assist, even with 5/5 BB of GTA, braking without the rear stepping out / oversteer is a like feathering a throttle on a Le Mans car with comfort medium tires - too much brake pressure at the slightest or too much steering input during braking will result in tail out.

Most of my cars in GT5 have 9/7 BB at most, some have 9/4 to reduce oversteer under heavy braking. The odd thing is I never have difficulty to rotate the car into corner, with 9/7 BB and proper trail braking ...is it maybe because I never use brake assist.

 

[Spagetti69]

Another good tire model test is race starts.

When I was doing the GT start stop tests I found the quickest start always to be 100% throttle.
I obviously haven't tried every car and it's been through a lot of patches so hopefully that's gone.

In Forza though 100% is not the best start.
I good example is the the new viper in rivals mode. I can tell the guys who are Full throttle on start and beat them off the line with throttle control modulating wheel spin.
A good example of a good tire model.

Try it yourself in Forza. Do a full throttle start and complete a lap and race your ghost. Practise goods starts and see for yourself.

 

[Christhedude]

Ideal setup in real world for qualifying would be some controllable oversteer on entry of low speed corners so you can power out early and and for mid or high speed to be stable as possible without too much understeer. I guess you choose a setup more for endurance though so a more understeer setup is probably the one you use. I bet it feels good when you hit the sweet spot in the Porsche GT3 Cup car .

The highlighted part in your sentence is wrong. Even though our races are 4 to 6h races, we run 100% identical Porsche super cup setups.


The only real difference is that we run 0.7 to 1.2 cm higher due to the extreme jumps & bumps on the Nordschleife and depending on Nordschleife track conditions, harder or softer springs then on a regular GP circuit. (but not by much)

Another fact that must be thought of, is that we dont just race on the GP circuit but on the Nordschleife, and every single race that I have raced so far, the Nordschleife is literally always a different track...


On another subject, believe me when I tell you that there is alot of "hacking" happening in real life too (especially in the last race)

 

[Ridox2JZGTE]

100% throttle start up in GT5 won't be fast on a powerful car, even more so if it's fitted with comfort tires, spin happy I've had enough times with all sorts of cars in my lobby with comfort medium restrictions and no assist - in a race, good start plays a huge part in winning. Another case if its 4WD car, as in the real world, the best launch technique for Skyline R32-34 GTR, rev to at least above 5000rpm, then launch it while flooring the go pedal.

 

[Scaff]

The rear brake bias in GT5 that people talk about here is surely used with brake assist enabled right ? Because I never drive in GT5 and GTA with brake assist, even with 5/5 BB of GTA, braking without the rear stepping out / oversteer is a like feathering a throttle on a Le Mans car with comfort medium tires - too much brake pressure at the slightest or too much steering input during braking will result in tail out.

Most of my cars in GT5 have 9/7 BB at most, some have 9/4 to reduce oversteer under heavy braking. The odd thing is I never have difficulty to rotate the car into corner, with 9/7 BB and proper trail braking ...is it maybe because I never use brake assist.

Nope - I've not noticed any major (i.e. as it should be) penalty for running a rear bias in GT5 until you turn ABS off all the way.

ABS in both GT5 and FM4 also acts as a form of EBD (brake force distribution), and as such you can run bias's that are simply silly. In FM4 you will suffer from it in the form of potential over-rotation and the loss of speed that results. In GT5 all you get is the over-rotation and no loss of speed with it, which is exactly why people use it.

100% throttle start up in GT5 won't be fast on a powerful car, even more so if it's fitted with comfort tires, spin happy I've had enough times with all sorts of cars in my lobby with comfort medium restrictions and no assist - in a race, good start plays a huge part in winning. Another case if its 4WD car, as in the real world, the best launch technique for Skyline R32-34 GTR, rev to at least above 5000rpm, then launch it while flooring the go pedal.

Yes and all you do in GT5 is sit with the tyres spinning away, no lateral forces at all (indicating potential weight distribution and suspension modelling issues)
and no realistic hook-up of the tyre grip (indicating the tyre modelling issues) you just start moving forward.



The above is a full throttle and step off the brakes launch of a Cobra on CH tyres, no correction is required at all and the tyres don't spin, grip and launch as they should. Rather they spin a bit and then you just move forward having dropped engine speed a bit, spin some more and throw a bit of smoke and then drive away (all in a totally straight line).

The GT series has done many things well over the years, standing starts is however most certainly not one of them.

 

[Tornado]

and no realistic hook-up of the tyre grip (indicating the tyre modelling issues) you just start moving forward.

Are you referring to axle hop and tires "chirping" during such launches? Just curious.

 

[BWX]

There is no engine brake in GT, just shift down 4 to 1 and watch, and then, go play forza shift down from 4 to 1, then see what happens to car.

Total BS.

 

[Odyofil]

Total BS.

go drive a real car, computer nerd. before replying me.

 

[Tornado]

go drive a real car, computer nerd. before replying me.

I think people are confused by your phrasing. Engine braking "exists" in the sense that when you do such a downshift the car will (eventually) force itself down to the max speed available in that gear and do so faster than just with brakes alone.






However, engine braking does not exist in GT5 as it does in real life because doing so will not force the drive wheels to basically lock up when they are suddenly and immediately forced into a much lower speed (though admittedly I don't have a wheel with a clutch pedal, I wouldn't imagine it should matter since you can engine brake with a slushbox), which is what should happen unless the transmission blows up when you do it. Which... hell:



Even Daytona got that right.

 

[sik180sx]

Can you record a video please, theres no compression lock up in DS3, and there is no video that claims theres a engine break, i mean, go 200 kmh, and shift down to 2 or 1... please record.

<a href="http://www.youtube.com/watch?v=TAw6P4wI8m8">YouTube Link</a>

You are right,there is no compression lock-up on the DS3,it is only when the clutch is activated with a wheel.I have also noticed no compression lock-up on race tyres,you just get a massive over-rev,but it still slows you drastically.
With the DS3,when dropping 4th to 1st gear,you dont slow down one bit,it will just carry on doing the same speed whilst violently bouncing of the limiter.