GT3 vs CSL - few questions

[Steve Rance]

Harris_I said:

And please tell us more about the heel and toe thing you said you didn't want to bore us with! (Not what it is, obviously, but how it relates to braking technique).

Hello Harris.

Ok, the 911 drivers here will know that the car is prone to trigger the ABS on the front wheels during heavy braking even on the very grippy cup tyres. The stiffer and more agressive you set up ( in terms of spring rate, shock rate and neg camber) the more pronounced the problem, the baking zone is extended as grip is lost, the weight transfers back off of the front axle and understeer on turn in will follow. This problem is compounded if the driver doesn't load up the front of the car by an initial relatively light application of the brake. To get around this the driver should bang in heal and toe downchanges as soon as the car is settled under braking and as soon as your engine revs allow. There is substantial amount of engine braking available during this time (especially if the car is fitted with sticky tires) in addition to be normal braking process. This process helps to further load up the nose prior to turn in. This 'double' braking techinque techinque is employed by some front running Carrera cup drivers, especially Richard Westbrook who uses this techinque to very good effect.

Does this make sense Harris?

Steve

[Dakkon]

Steve Rance said:

Harris_I said: And please tell us more about the heel and toe thing you said you didn't want to bore us with! (Not what it is, obviously, but how it relates to braking technique). Hello Harris. Ok, the 911 drivers here will know that the car is prone to trigger the ABS on the front wheels during heavy braking even on the very grippy cup tyres. The stiffer and more agressive you set up ( in terms of spring rate, shock rate and neg camber) the more pronounced the problem, the baking zone is extended as grip is lost, the weight transfers back off of the front axle and understeer on turn in will follow. This problem is compounded if the driver doesn't load up the front of the car by an initial relatively light application of the brake. To get around this the driver should bang in heal and toe downchanges as soon as the car is settled under braking and as soon as your engine revs allow. There is substantial amount of engine braking available during this time (especially if the car is fitted with sticky tires) in addition to be normal braking process. This process helps to further load up the nose prior to turn in. This 'double' braking techinque techinque is employed by some front running Carrera cup drivers, especially Richard Westbrook who uses this techinque to very good effect. Does this make sense Harris? Steve

In another thread I was one of the few advocating the advantages of engine braking with people saying how you can lock the rears if done badly, nice to see a fellow engine braker speak up

[DoctorD]

Steve Rance said:

Good drivers have been doing this for years in 911's. If you can fire the car into corners like this again and again, you win races. That is why the 911 in all of it's guises is one of the most prolific race winners of all time. It is also why more have also been stuffed into the armco or hedges than most other car. In the hands of a good driver the 911 is an incredible driving tool. Unfortunately it can also be a lethal weapon in the wrong hands. I hope that this makes some sense to you. Steve

This is another reason why I found the Boxster S a really boring car to own. Since I wasn't using my GT3 as often as I wanted to (and thought £80k sitting in the garage was a bit wasteful) I bought a Boxster S on the basis that I'd use it more often and surely a mid-engine Porsche would be an advance on the 'old fashioned' rear engine 911. Big mistake! The Boxster didn't respond well to the weight transfer techniques I was used to employing with the 911, in fact it didn't respond to anything really. It just turned in, stayed balanced and neutral until it reached the limits of grip and usually understeered. The 911 by comparison is much more adjustable and rewards driver skill and error in equal measure (although it's virtually idiot proof these days), but skill still counts big time.

The CSL by comparison is easier but it's still much more fun than I remember my Boxster, mainly because it can be steered on the throttle.

Driving quickly around any circuit is all about maintaining and optimising chassis balance and therefore mechanical grip. The GT3 is a little more difficult than most cars but it's not alchemy, you just need to 'think' about weight transfer and that little thing called the traction circle.



>> Edited by DoctorD on Monday 7th March 11:04

[evoblade]

Steve is pretty much spot on with his info here.

One thing though, why is anyone comparing a CSL to a GT3-RS anyway? It is easily an equal to a GT3, and a badly driven GT3-RS.

Let's face it - most GT3-RSs I have seen are driven appallingly. Same as most 360 Stradales. It was a pleasure to follow Steve Rance around on many occasions as the bloke can actually drive very well. Proper driver in a proper car driving properly. not something that happens often at a track day LET ME TELL YOU!

Shame you aren't going to Spa in April 6th/7th. My CSL will be in it's latest incarnation.

380bhp and sub 1100kgs

Did I mention the 13 inch wheels? LOL

There is a big point Steve made, which I have said before (not sure if on this thread though) which is the CSL is much easier to extract the maximum from. The GT3 isn't. The same is true of race cars. Consistently in Britcar, it has been the M3 based cars that are the quickest, particularly in the wet.

Personally, I prefer my Stradale to both of em!!!

[Harris_I]

Thanks Steve, that makes perfect sense.

[evoblade]

Steve, I thought you had the JRZs on?

It was so long ago, I cant really remember.

I too wouldn't read much in the lap times, just trying to show the CSL was in the zone in my then rookie hands.

I still lust after the RS. If only it was comfortable for me! Still if prices keeping dropping.... mmmm

Can't really justify it with the Stradale, and can't bear to be parted from that car!

[Steve Rance]

evoblade said:

Steve is pretty much spot on with his info here. One thing though, why is anyone comparing a CSL to a GT3-RS anyway? It is easily an equal to a GT3, and a badly driven GT3-RS. Let's face it - most GT3-RSs I have seen are driven appallingly. Same as most 360 Stradales. It was a pleasure to follow Steve Rance around on many occasions as the bloke can actually drive very well. Proper driver in a proper car driving properly. not something that happens often at a track day LET ME TELL YOU! Thank you for the compliment, it is much appreciated. You recall correctly, the car was fitted with the JRZ springs and shockers fitted by Parr Motorsport. I would estimate that the set up is worth a couple of seconds around Spa. 380BHP in 1100kg. . . I think you may well now have the advantage!! I am currently talking to a team to go racing in the Brit car for 2006 in a cup car or GT3RSR. Look forward to mixing it with you on the track. Steve Shame you aren't going to Spa in April 6th/7th. My CSL will be in it's latest incarnation. 380bhp and sub 1100kgs Did I mention the 13 inch wheels? LOL There is a big point Steve made, which I have said before (not sure if on this thread though) which is the CSL is much easier to extract the maximum from. The GT3 isn't. The same is true of race cars. Consistently in Britcar, it has been the M3 based cars that are the quickest, particularly in the wet. Personally, I prefer my Stradale to both of em!!!

[Steve Rance]

In another thread I was one of the few advocating the advantages of engine braking with people saying how you can lock the rears if done badly, nice to see a fellow engine braker speak up [/quote]

Engine braking is effective when the grip of the tyre is greater than the ability of the braking system to utilize it or when the car will benefit from the resultant weight transfer. It requires a sensitive touch from the driver when judging revs and engaging the clutch.

Steve

[Steve Rance]

Engine braking is effective when the grip of the tyre is greater than the ability of the braking system to utilize it or when the car will benefit from the resultant weight transfer. It requires a sensitive touch from the driver when judging revs and engaging the clutch.

Steve

[evoblade]

Excellent Steve! Be good to see you in Britcar.

It is becoming a really popular series.

if you are looking for a seat in the 24hr, and have budget, I still have a couple of places in my car.

[burzel]

Hi evo blade
Ref your BMW,i have seen it down at Simpson a few times, looks like a nice car, that goes well around donny! then. The simpson boys seem to be good,they now set my cars up,and have done a great job so far.If you are doing the brit car 24 hr ,whats the budget on a seat?
I would still like to see some times posted here on spa lap times in the gt3rs,on mich cups and csl on descent tyres .Not comparing them ,as you rightly said they are not comparable really .Just interested in the times ,As good drivers!!
I think the 911 driving style mentioned in a gt3,with abs could be quicker !Turn in on abs ,no under steer as weight is well and truly planted on the nose ,then balance the car with throttle, and boot it as soon as you can see the exit .As i was once told and shown by a top porsche racer,dont brake like a pussy,use the bloody brakes hard and then leave them alone!Especialy if they have abs.Seconds fell off my lap times.

If you are getting bounce on the springs ,your dampers would need adjusting,i would have thought.
ref the engine braking ,normally equals gearbox breaking eventually in races, if not done at the correct speed/revs etc .Pads are much cheaper to replace ,than gearboxes .Heel and tow helps keep the car flat and balanced shorly ,and able to get the correct gear in & out of a corner smoothly .Im sure we have all done a rushed gear change ,because we have out braked our selves ,and not done a very smooth down shift ,which normally kicks you in the back side if its wet! A 911 can normally get away with it in the dry ,or break something.

[Steve Rance]

For reference my time around spa was 2.49. In a standard GT3RS with Cup tyres and JRZ shock absorbers and springs.

Your suggested driving style in a 911 will not work. It is imperative that th ABS is not triggered. It cuts the front brake bias in half, the weight shifts rearwards because the front tyres are slippng, the front springs will de compress, you will miss your turn in point because you are travelling too quickly and the car will understeer off of the circuit. Heal and toe will not brake any gearbox if it is done correctly and most good international racing drivers use engine braking if tyre grip is greater than maximum braking reistance. A quick racing driver will rarely intentionally unsettle a car, it scrubbs off speed and - particularly in endurance racing - is very hard on tyre wear.

Perhaps I was not clear about braking. Once the initial braking is done to drop the nose (approx 2 tenths of a second) the brakes are applied as hard as is possible without deploying ABS. This is dictated to by tyre grip. My front pads and disks last 3 - 4 days, So I can safely say that I am not light on my brakes!!.

At Paddock bend my braking point is 50 meters, my data traces at Spa show that I did not brake at Eu rouge until the compression, I entered the corner flat with 150mph showing on the digital spedo and 143 showing on the data logger. Using the above techinque and the positive G of the compression, I braked settled the car and got back on the power before the end of the compression. If I had employed your technique, I would probably have been killed.

Interesting theory though!!

Steve R

[johnny senna]

I think Steve Rance and burzel should have a race....

Runs for cover!!!!!!!!!!!

[GuyR]

Steve,

Your points are interesting and I'd love to have a ride with you one day to observe.

The only points I'd make about engine braking from a non-racing perspective is that surely if the car is underbraked at the rear it makes sense to uprate the rear brakes rather than try to get round the problem with engine braking. My GT2 certainly feels more front-biased in the braking than my 993RS did.

The other problem is that there have been some cases of GT2s and GT3s where they have blown engines and have subsequently had trouble with Porsche due to the ecu logging 'mechanical over-revs' ie exceeding the maximum revs (not to be confused with hitting the re-limter whilst accelerating). This is only caused by missing a gear or by badly executed down-shifts whilst engine braking.

I guess my point is that it's only for people who really know what they are doing.

I also would have thought that Porsche's efforts to reduce rotational inertia in the GT3RS with titanium con-rods and lightweight flywheel etc, would have reduced the amount of engine-braking available in comparison to many other cars.

Guy

[Dakkon]

GuyR said:

Steve, The other problem is that there have been some cases of GT2s and GT3s where they have blown engines and have subsequently had trouble with Porsche due to the ecu logging 'mechanical over-revs' ie exceeding the maximum revs (not to be confused with hitting the re-limter whilst accelerating). This is only caused by missing a gear or by badly executed down-shifts whilst engine braking. I guess my point is that it's only for people who really know what they are doing. Guy

Firstly, this is a really interesting thread, lots of reasoned opinions which is great.

Second, I am in no way a race driver having driven a few sports cars in my time and done a few tracks days, but I have engined braked all my life, was the way I was taught to drive by my dad.

I don't see the risks of blowing engines on over rev on a non sequential box, brake, heal-toe the down shift of one gear whilst continuing braking. With a sequential box I can see that its possible to go down through the box more than one gear when the adrenaline is flowing, but on a normal H box, very difficult surely?

[beaver]

Blimey this is a corker of a thread. But what happened to the original poster - "Shotokan", has he made an informed decision after all this ?!

[steve rance]

GuyR said:

Steve, Your points are interesting and I'd love to have a ride with you one day to observe. The only points I'd make about engine braking from a non-racing perspective is that surely if the car is underbraked at the rear it makes sense to uprate the rear brakes rather than try to get round the problem with engine braking. My GT2 certainly feels more front-biased in the braking than my 993RS did. The other problem is that there have been some cases of GT2s and GT3s where they have blown engines and have subsequently had trouble with Porsche due to the ecu logging 'mechanical over-revs' ie exceeding the maximum revs (not to be confused with hitting the re-limter whilst accelerating). This is only caused by missing a gear or by badly executed down-shifts whilst engine braking. I guess my point is that it's only for people who really know what they are doing. I also would have thought that Porsche's efforts to reduce rotational inertia in the GT3RS with titanium con-rods and lightweight flywheel etc, would have reduced the amount of engine-braking available in comparison to many other cars. Guy

Guys

I will be at Bedford in the Parr Motorsport GT3 RS on Friday March 25th. The team have put a new set up on the car and I will be shaking it down on the day. I can do a few rides after lunch if anybody is interested. Just hunt me down in the pit lane and say hello. It may be a bit manic but I will give you all the time I can. would be good to see you there.

Steve R

[m12_nathan]

I'll take you up on that!

[burzel]

Not sure how you brake as hard as possible and not deploy the abs. I thought the whole point of abs is to go faster,so that you can brake with more control and either turn in while the abs is chattering to you! or come of the brakes and balance the car earlier if you are able to.I will stand corrected if i am wrong!
The fastest time you can get out of a car, is to the limit of adhesion of your tyres for braking accelerating and cornering, which varies from surface to surface etc
911,s drive very well like this, with the key element being able to balance the car as soon as possible from the braking.
Early 911 with no abs, for your fastest times you had to take it to the slip point just, and balance again. If you are not getting to these points you are not as quick as you could be ,that’s all i am saying.
To enable me not to come off at o rouge i brake before the compression, if needed and then balance the car on the throttle, so that it does not come of, hopefully.

I learned a interesting one from melv ref abs, I thought the 964 cup car had abs as standard like the rs ,it has but its switchable .As most drivers did not want it to start with ,but then left them switched on ,because they too learnt to drive with the abs on and working ,they found they were quicker wet and dry no doubt.
I know we should not talk about lap times on track days really, as its a agreeable no no, sure there are some slower drivers out there, but it may be there first time out or new tyres, new car etc We all have to start some where, i remember my first track day well, I was almost frightened to take my eyes of the track to look in a mirror. So we should all not forget that, and i know its easy to. The best bit is learning every time you go out.

[DoctorD]

Paul, I agree with the logic of your argument but I've been in the passenger seat with Steve R and watched him do as he describes. It certainly works with the RS although it's a more aggresive style than I used to use when racing a 964 RS (in the dim and distant past). To be fair, I can brake to the limit of the tyres grip in my CSL and still not activate the ABS (on track) and yet on the road on loose surfaces I know it still works. Perhaps the RS is similar. ABS systems are so finely tuned these days that on the best cars they are really unobtrusive.