Which Has More Potential In The Long Run?

[djr81]

djr81 Are you messing with us? Not saying it's incorrect (or correct), first you say that the less load on a tyre the higher coefficient of grip but now you say with a torque split controller to put as much power to the front wheels as possible. So in a way, on top of the already understeering and front heavy R32 GTR, you give it more understeer?

Well it is your assertion that the GTR understeers. I have spent alot of time & money to get my car balanced. Yes it still does have an amount of understeer mid corner but, depending on what gear etc you are in, even with the torque all the way forward it will power on oversteer. Compared to a WRX or an Emo it is positively tail happy.

At the end of the day you set it up to do what the lap timer says is quicker and drive it accordingly.

[Nee-san]

djr81 Are you messing with us? Not saying it's incorrect (or correct), first you say that the less load on a tyre the higher coefficient of grip but now you say with a torque split controller to put as much power to the front wheels as possible. So in a way, on top of the already understeering and front heavy R32 GTR, you give it more understeer?

Well I take it back

Grip and CoF are two completely different things and No, he is not f**king with you it is a non Newtonian non-Linear relationship between vertical load and coefficient of friction.

See the graph posted in some of the post's above for the true relationship.

[TurboDoseBro]

Coefficient of grip and coefficient of friction are pretty much the same thing. It's like saying globes and bulbs. So if it is true then you are only suupporting my side of the argument. That a lighter car (GTS-T) doesn't need as much coefficient of grip on the tyres to go just as fast or faster than a heavier car (GTR).

Sample calculation:

For this we will assume the weight distributions of the GTS-T is 54F:46R and GTR is 58F:42R. Weight is also with driver. For simplicity we'll also assume the weight on both left and right sides are symmetrical. Weights are calculated according to a RB26 in each vehicle.

So:

GTS-T

54 : 46

1400

F = 756kg

R = 644kg

FL = 378kg (833.35lb)

FR = 378kg

RL = 322kg (709.89lb)

RR = 322kg

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

GTR

58 : 42

1600

F = 928kg

R = 627kg

FL = 464kg (1022.95lb)

FR = 464kg

RL = 313.5kg (691.15lb)

RR = 313.5kg

So on the graph (in regards to each individual static tyre load):

As you can see, not only does the GTR's coefficient of grip on the individual front and rear wheels differ significantly more than that of the GTS-T, the front wheels are also caught in the exponential fall of the coefficient of grip. This would increase understeer and narrow the traction circle for the front wheels.

Where is your god now?

[BoyWhoCriedWolf]

4 pages and now a graph

Have you driven a GTR?

If not, gtfo.

[djr81]

Coefficient of grip and coefficient of friction are pretty much the same thing. It's like saying globes and bulbs. So if it is true then you are only suupporting my side of the argument. That a lighter car (GTS-T) doesn't need as much coefficient of grip on the tyres to go just as fast or faster than a heavier car (GTR).

Sample calculation:

For this we will assume the weight distributions of the GTS-T is 54F:46R and GTR is 58F:42R. Weight is also with driver. For simplicity we'll also assume the weight on both left and right sides are symmetrical. Weights are calculated according to a RB26 in each vehicle.

So:

GTS-T

54 : 46

1400

F = 756kg

R = 644kg

FL = 378kg (833.35lb)

FR = 378kg

RL = 322kg (709.89lb)

RR = 322kg

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

GTR

58 : 42

1600

F = 928kg

R = 627kg

FL = 464kg (1022.95lb)

FR = 464kg

RL = 313.5kg (691.15lb)

RR = 313.5kg

So on the graph (in regards to each individual static tyre load):

As you can see, not only does the GTR's coefficient of grip on the individual front and rear wheels differ significantly more than that of the GTS-T, the front wheels are also caught in the exponential fall of the coefficient of grip. This would increase understeer and narrow the traction circle for the front wheels.

Where is your god now?

A couple of points:

The graph is clearly not that for a tyre used on a GTR. It is simply there to illustrate the point about the relationship between friction coefficient and load.

Secondly and more importanly, there are a number of other effects your calculation does not include which are fundamental to the way a car is set up. In no particular order:

Camber settings. The relationship between camber angle and the lateral grip of a tyre is well known. So in our case it is easy to use more camber on the front end that the rear (Which is typical in anycase as camber hurts traction) to help balance the car.

Spring rates. As I mentioned in an earlier post what spring rates you use has a strong effect on the load transference front to rear when the car is cornering. In this instance a softer front spring will allow the front to grip better.

Anti roll bars. These have the same effect as springs in roll. A harder rear bar will load the rear tyre more & promote oversteer.

Roll centres. The difference between the centre of gravity and the roll centre (which are different front and rrear) defines the roll couple. This in conjunction with the roll stiffness of the car is also used to preferentially load one end of the car up.

Between all these tiems there are enough tools in the tool box to compensate for the poor weight distribution. Added to which in any half developed track car weight reduction and relocation are two items that are very high on the agenda.

[SKITTLES]

4 pages and now a graph

Have you driven a GTR?

If not, gtfo.

+1

math/science all you want.. with slight margins between two cars, the competition comes down to the driver and not what they're driving.

I'm sure a properly driven RWD would beat a semi-properly driven AWD, am I right?

Just my 2c..

[BoyWhoCriedWolf]

Yeah, thats what ATCC 90,91,92 taught me.

[djr81]

+1

math/science all you want.. with slight margins between two cars, the competition comes down to the driver and not what they're driving.

I'm sure a properly driven RWD would beat a semi-properly driven AWD, am I right?

Just my 2c..

No. You are so profoundly wrong it makes baby Jesus cry.

[Nee-san]

A couple of points:

The graph is clearly not that for a tyre used on a GTR. It is simply there to illustrate the point about the relationship between friction coefficient and load.

Secondly and more importanly, there are a number of other effects your calculation does not include which are fundamental to the way a car is set up. In no particular order:

Camber settings. The relationship between camber angle and the lateral grip of a tyre is well known. So in our case it is easy to use more camber on the front end that the rear (Which is typical in anycase as camber hurts traction) to help balance the car.

Spring rates. As I mentioned in an earlier post what spring rates you use has a strong effect on the load transference front to rear when the car is cornering. In this instance a softer front spring will allow the front to grip better.

Anti roll bars. These have the same effect as springs in roll. A harder rear bar will load the rear tyre more & promote oversteer.

Roll centres. The difference between the centre of gravity and the roll centre (which are different front and rrear) defines the roll couple. This in conjunction with the roll stiffness of the car is also used to preferentially load one end of the car up.

Between all these tiems there are enough tools in the tool box to compensate for the poor weight distribution. Added to which in any half developed track car weight reduction and relocation are two items that are very high on the agenda.

This +1

Also, the figures in your example are not only wrong, they are quite misleading as you are using static CoF in a transiet and dynamic example IE a Race car doing laps.

Further, the GT-R differs from Normal AWD systems in that it is not consistently reducing the traction circle of the front wheels as it is a variable system (Closed loop control system)

Hence front torque is transferred only when traction becomes an issue IE corner exit.

I have seen Mark Skaife comment that the 32 was one of if the not best car on turn in corner entry he has driven, this goes against everything the "experts" on this forum and abroad like to spruik about.

Also,

Grip as you speak of it is generally thought of as the tractive effort of the Tyre with the CoF being something which is completely different (CoF being dimensionless multiplier)

This is actually an important mathematical distinction.

And yes, we could probably bottle the tears of the baby jesus with this thread.

[TurboDoseBro]

First of all, no I haven't driven a GTR. Don't even think I've been inside one. Also barely driven a GTS-T. R32 GTS25 is my daily. This thread was started on theory as mentioned in first post to compare the theory to the experiences and theories of yourselves. Here we are assuming a good consistent driver. Ofcourse better driver = better results.

Yep sorry I roughly plotted the points on the graph to illustrate to rough differences between GTR and GTS-T from factory (One of the most variable factor). It was just a general figure pointing out that less weight overall = more coefficient of friction as there is less weight thrown on each tyre around the track. You guys really are making it difficult (which is good).

Regarding the torque split controller which only one person replied to, and said that they would recommend the use of one, that would mean the AWD closed loop variable system is indeed obsolete and the traction circle does remain constant.

If GTRs have such good turn ins and AWD systems are the be all and end all ultimate of an automobile's drivetrain, how did the V8 Supercar Commodore VT yes Commodore (with 4 doors and V8 and all) beat the Group A GTR's (with all it's advantages) lap record by more than 10 seconds? I mean this is approaching the modified production car overall lap records. Even for TA. You can't tell me that you can't make a GTS-T just as fast as a Commodore VT if not, faster. Dunno if the V8 Supercars or Group A had the carbon fibre body or not but either way the weight of a fully stripped GTS-T will still be roughly the same as a VT V8 Supercar.

Edited May 19, 2011 by TyresBro

[BoyWhoCriedWolf]

First of all, no I haven't driven a GTR. Don't even think I've been inside one. Also barely driven a GTS-T. R32 GTS25 is my daily. This thread was started on theory as mentioned in first post to compare the theory to the experiences and theories of yourselves. Here we are assuming a good consistent driver. Ofcourse better driver = better results.

Yep sorry I roughly plotted the points on the graph to illustrate to rough differences between GTR and GTS-T from factory (One of the most variable factor). It was just a general figure pointing out that less weight overall = more coefficient of friction as there is less weight thrown on each tyre around the track. You guys really are making it difficult (which is good).

Regarding the torque split controller which only one person replied to, and said that they would recommend the use of one, that would mean the AWD closed loop variable system is indeed obsolete and the traction circle does remain constant.

If GTRs have such good turn ins and AWD systems are the be all and end all ultimate of an automobile's drivetrain, how did the V8 Supercar Commodore VT yes Commodore (with 4 doors and V8 and all) beat the Group A GTR's (with all it's advantages) lap record by more than 10 seconds? I mean this is approaching the modified production car overall lap records. Even for TA. You can't tell me that you can't make a GTS-T just as fast as a Commodore VT if not, faster. Dunno if the V8 Supercars or Group A had the carbon fibre body or not but either way the weight of a fully stripped GTS-T will still be roughly the same as a VT V8 Supercar.

Wat?

gtfo

[iplen]

Face....PALM!!!! Tyres, if you seriously believe what you wrote, buy a VT for $2000, put an old 308 in it, cause they don't even use a gen3, take the independent arse end out, chuck a big wing on the back, and beat us all.

[djr81]

Regarding the torque split controller which only one person replied to, and said that they would recommend the use of one, that would mean the AWD closed loop variable system is indeed obsolete and the traction circle does remain constant.

All the torque split controller does is reduce the influence of lateral grip on the way the system works. Nissan programmed the system to reduce front torque when the car is cornering (relative to driving in a straight line) so it behaves more like a RWD & is perceived to be more fun on the road. There are gains to be made by changing this. Or in other words gains to be made by making the GTR behave less like a GTST.

If GTRs have such good turn ins and AWD systems are the be all and end all ultimate of an automobile's drivetrain, how did the V8 Supercar Commodore VT yes Commodore (with 4 doors and V8 and all) beat the Group A GTR's (with all it's advantages) lap record by more than 10 seconds? I mean this is approaching the modified production car overall lap records. Even for TA. You can't tell me that you can't make a GTS-T just as fast as a Commodore VT if not, faster. Dunno if the V8 Supercars or Group A had the carbon fibre body or not but either way the weight of a fully stripped GTS-T will still be roughly the same as a VT V8 Supercar.

Due to them not running a differential (Ie they have a locked rear axle with a pinion, spool & nothing else) the V8's dont turn in at all well. Which is why the drivers have to carry so much brake into turns. So compaired to a V8 a GTR will turn in brilliantly. The amount of commonality between a Gibson GTR & a stocker is massively more than a V8 supercar & a VT.

Group A cars had what the production cars had. That was, after all, the whole point. Actually the GTR had a heap of ballast as well.

Does a completely different set of rules & many years of tyre development explain it away. Absolutely.

The ATTESSA system is not the greatest in the world. It is, however, sufficiently useful to be more than worth the weight. Which is the point, after all.

[BoyWhoCriedWolf]

Bathurst lap record 2.08, Whincup, 07.

GTR quali 91, 2.12

Difference 4 seconds and 16 years.

tyresbro, shaddup.

[Nee-san]

Group A

Series for highly modified production cars.

V8SC

Series for two particular makes of sport sedan (that's pretty much what they are)

Development goes a long way in 20 years, this would easily explain the variance in Laptime.

DJR81 has already gone into detail about diff's so I will leave that alone.

What your actually asking is developmentally equal, will a GTS-T be equal to a GT-R, but then you diverged onto GT-R versus the rear wheel drives of the world.

In any case, the answer is still no.

Djr81 summarised it very succinctly in saying that the benefit of the system outweighs the weight penalty, this is something which Nissan would have calculated very early on in the development of the R32 series.

[BoyWhoCriedWolf]

Given 16 years I would have expected better than 4 seconds.

[TurboDoseBro]

Alright guys, I'm all out LOL. :worship:

[BoyWhoCriedWolf]

good

[mad082]

First of all, no I haven't driven a GTR. Don't even think I've been inside one. Also barely driven a GTS-T. R32 GTS25 is my daily. This thread was started on theory as mentioned in first post to compare the theory to the experiences and theories of yourselves. Here we are assuming a good consistent driver. Ofcourse better driver = better results.

Yep sorry I roughly plotted the points on the graph to illustrate to rough differences between GTR and GTS-T from factory (One of the most variable factor). It was just a general figure pointing out that less weight overall = more coefficient of friction as there is less weight thrown on each tyre around the track. You guys really are making it difficult (which is good).

Regarding the torque split controller which only one person replied to, and said that they would recommend the use of one, that would mean the AWD closed loop variable system is indeed obsolete and the traction circle does remain constant.

If GTRs have such good turn ins and AWD systems are the be all and end all ultimate of an automobile's drivetrain, how did the V8 Supercar Commodore VT yes Commodore (with 4 doors and V8 and all) beat the Group A GTR's (with all it's advantages) lap record by more than 10 seconds? I mean this is approaching the modified production car overall lap records. Even for TA. You can't tell me that you can't make a GTS-T just as fast as a Commodore VT if not, faster. Dunno if the V8 Supercars or Group A had the carbon fibre body or not but either way the weight of a fully stripped GTS-T will still be roughly the same as a VT V8 Supercar.

for starters there was nearly 10 years developement difference. secondly, they are in 2 different race categories and different rules apply to them. you might as well ask why a f1 car is faster than a formula ford. they are both open wheelers after all....

the changes in regulations are also the reason why current v8 supercars aren't really much faster than they were 10 years ago. back then they could buil motors that were time bombs putting out more power than they currently are as they didn't have to last as long. it is also the same reason why most f1 lap records haven't been broken in the past 5 years. all regulations these days are more for cost cutting measure (in other words, making things more reliable so they don't have to replaced after practice, qualifying and each race),

Bathurst lap record 2.08, Whincup, 07.

GTR quali 91, 2.12

Difference 4 seconds and 16 years.

tyresbro, shaddup.

the qualifying lap record for the v8's is a low 2:06 or was it a very high 2:05? i can't remember, either way lowndes set it last year in practice, but previously before that it was greg murphy from back in about 2006.

Given 16 years I would have expected better than 4 seconds.

see my first reply. but 4 seconds is a hell of a long time once you start getting to the pointy end of performance.

[zebra]

Well from quite a few accounts, the GTR gets faster the closer to 50/50 torque split it gets.

There was a certain R32 GTR sport sedan, where the team solid locked to 4wd system to 50/50, and went 1 sec per lap quicker, only problem was it would break the front diff housing off the sump under brakes as it couldnt handle the stress.

The GMS GTR's ran a lever in the cabin to manually adjust the torque split.

In the Skyline Chassis the 4wd system simply works better than RWD only, infact works better in most cars.

There was a reason Colin Chapman started building 4WD F1 cars in the 70's until they too were banned.

WRX's understeer like a biartch from factory, but fit a helical front LSD and they turn in like a deamon.

The aftermarket can fix most AWD/4WD shortcomings that factory standard cars have, ala: WRX and early EVO's, GTiR pulsars etc.