Lap times - GTST vs GTR

[Snowman]

Ok Roy - you theory should be tested at Phillip Island by the way (back to the GTST v GTR). You car is more powerfull, lighter and running better tyres than Scotsman.

You should in theory beat him. Do it.

[adznight]

Yeah Ben's car was squating soooo much out of corners etc, so much power!

[benjiman74]

Ok Roy - you theory should be tested at Phillip Island by the way (back to the GTST v GTR). You car is more powerfull, lighter and running better tyres than Scotsman.

You should in theory beat him. Do it.

I'm a realist, not a theorist. $100 on the R and i'll give 2:1 odds.

[Snowman]

Oh another funny ones is when you have a GTR driver in the passenger seat and they say "break later, break later". The GTS-T and GTT breaks sure don't hold up like the GTR's. Any later and my car would be a smear on the wall, well an even bigger one than it is

HAHA - I only just re-read this - I'm pretty sure the GTR driving passenger didn't say "brake later, brake later" - he infact said "TURN later, TURN later".

There's a big difference. Roy can tell you all about turning in too early.

[adznight]

Yeah your right, I stand corrected. But still, any later and the bum would of been round the corner first, I think street tyres had a lot to do with that

[Roy]

I'm a realist, not a theorist. $100 on the R and i'll give 2:1 odds.  

LOL...doesnt Scotsman have 240odd rwkws?

LOL...If Nige can tune my car to make a comfortable mid 230rwkws (I have see the turbo support 260rwks) then ill take that bet:)

Not that i want to beat a GTR, but i want to get into the sub 1:50s around PI and down to around 1:25-1:27s around Sandown so those times are pretty similar to what some of the std turbo GTRs are doing.

As for turning in too early! Im the KING:(

As for brakes, i don tknow, if someone else can explain it to me. As for him having braking problems after a few laps, well his car does have more power then a Supercar nad weigh about 300kgs more.

I dont know if im righ about the brakes thing?!?!? Its just that i cant think how they are going to stop you any quicker then say a good package like Snowmans with nice two piece rotors, good std caliper run with nice pds and fluid that gets changed occassionally (LOL...looks at Snowman:))

[benjiman74]

Scotsman has 220odd rwkw's.

Let me know if your car makes the 230rwkw so I can book a nice seafood restaurant to spend the $100 - lol.

with respect to the brake thing haven't you already answered your own question with the revolving door analogy?

[GTRgeoff]

Just to support Roy, the number of pistons and the size of the swept area help to modulate the braking application but won't slow the car any better until after a nuber of applications when the heat comes into effect. The contact patch is still the same and will still lose traction at the same torque. the benefit of that added brake "feel" allows greater subtlety in using all of the available braking force.

I'm not surprised Ben is running out of brakes at his pace. No he just has such a massive setup advantage Snowie as well as higher corner speed but you are doing pretty good with your level of experience and setup.

[Snowman]

Your only supposed to change that Castrol SRF fluid once every 6 months / 6 track days aren't you???

:confused:

BTW - Ben's brakes dont have problems after a few laps - its the engine that needs the rest. Gets hot despite all the cooling he has. Don't know why?

[Snowman]

I thought Chris had 230rwkw's. Either way it damn close to you Troy and you are a lot lighter - and the Dunlops are better than the Advans. Your suspension is set-up decently. Don't know about brakes but PI isn't really dependant on them.

No excuses. I'm happy to join Ben for dinner.

[benjiman74]

The contact patch is still the same and will still lose traction at the same torque.

but can the caliper clamping down on a smaller diameter rotor reach the traction threshold as early? In my previous car I went from 270mm rotors to 330mm rotors and even on the first application the stopping distance was greatly reduced.

[GTRgeoff]

That's more a matter of braking feel. Were you running ABS as that can highlight the difference without any operator limitations? With the smaller swept area and smaller pad/piston/master cylinder you can lock up too easily. Also if the old calipers and master cylinder are a bit in need of a freshen up you will have problems modulating. Finally, brake pads make a world of difference. I'm lucky enough to have a stock R33 GTSt in the driveway for comparisons and the Bendix pads have good initial bite but just suck for real braking. I know mine are in desperate need of a rebuild as they are notchy under increasing pedal pressure now. Here's hoping I can find a decent price for a rebuild kit.

[Duncan]

sorry I don't beleive that rotor or caliper size makes any difference to braking distances until the rotor, caliper or fluid is too hot.

tyres compound, width, diameter...yep!

camber...yep!

car wieght...yep!

but any car from a crappy kingswood to a gtr has enough braking powre to lock a brake when its cold.....its only after a few stops there is a difference.

[Roy]

Torque = F x D, which is force times distance. So stand at a half open door and push it where the handle is. Piece of piss right? Now try and do the same thing but right near the hinge. You have to apply a hell of a lot more load to close the door as the D (distance) is a lot lower

So applying that to the braking thing, as your caliper’s pistons are now clamping the rotor around 20-20mm further away front he rotor centre, the torque to slow the rotor is much greater for the same amount of pedal pressure. So provided you have rubber that can maintain traction with the road it is possible to better control the rotor and even slow it quicker.

Rather then compare me to Scotsman and GTRs, lets put the money on me getting into the 1:50s at Phillip Island and into the 1:25s around Sandown. LOL, im in for one hell of an ear beating when I fail miserably. And it not about one upmanship, but im just setting some goals for me and my car based on the lap times of production cars. Obviously im never going to be really quick as the RB20 just cant punch the car out of corners, or pull from 160km/h like its bigger, more powerful RB engine.

And to clarify, its not a GTR suck thing. Obviously they don’t. But its more a RWD don’t necessarily suck thing. Where you only have to have the tyres hang together for about 4 laps can tyre wear really come into it?

At the end of the day I don’t really care how quick or slow my car is, I like my car and its great fun:) Only I don’t want to have spent all this money on it not to go any quicker.

LOL..im just thinking out aloud, not trying to upset anyone or wanting to argue. I don’t know if im right, im probably wrong, but its just some of the logic behind my approach to modifying my car

[fatz]

thats what i like to here

[GTRgeoff]

sorry I don't beleive that rotor or caliper size makes any difference to braking distances until the rotor, caliper or fluid is too hot.

tyres compound, width, diameter...yep!

camber...yep!

car wieght...yep!

but any car from a crappy kingswood to a gtr has enough braking powre to lock a brake when its cold.....its only after a few stops there is a difference.

One other thing...

Driver...Big yep! At PI I was outbraking HQ racers on slicks and that Laser on slicks and a couple of HSV's on track rubber so it must be the driver in that case. put a good one in and I'd be shown up like I should

Unfortunately my brakes were going off very fast at Sandown and I went from 150 m at turn 1 to 175 to 200 then 220 to try to stop. I feel the front pads are too low and overdone and the whole shebang needs a service.

And Roy, on the road rubber the first flying lap is usually the fastest and then they start to go off. You are right on the braking torque. BTW, I vote all the GTR drivers disable their ABS so they discover what braking control is.

[Duncan]

hahhaa and ruin those expensive semi slicks at the first braking marker?

ABS is essential to keep expensive tyres un-flat spotted

[GTRgeoff]

I didn't spot roy's in the 2 sessions I stole, although I did compression slide lukey heights a little

Cheater tyres, ABS and AWD and you say you're having fun...........................

[Duncan]

:bahaha: don't forget power steering rofl

you are right, no abs, no power steer, 2wd is far more challenging, but the other option is just so forgiving of mistakes when you are learning.

[Sydneykid]

but can the caliper clamping down on a smaller diameter rotor reach the traction threshold as early? In my previous car I went from 270mm rotors to 330mm rotors and even on the first application the stopping distance was greatly reduced.

What that means is the larger diameterr rotors have more leverage to slow the car down for the same pedal pressure. But Roy is correct, if you pushed harder on the smaller rotors you would get the car to stop in the same distance. I agree wiht Duncan, ultimately in a road car it is the weight of the car, its tyres and suspension that determin the minimum stopping distance.

Just tor clear something up from a previous post, it is my recollection that ~20% slower rotation of the tyre is the best for stopping distance on a hard surface. On loose gravel or dirt, 100% slower rotation (locked up) is actually best for shorter stopping distances as it piles the dirt up in front of the tyre. That's why ABS on dirt or loose gravel is not a good thing.