Another run at Lime Rock in the GT4
#31
Thread Starter
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Keep your Stability Control on if you don't want to wad up your $100k car - especially with only 20 track days. Why take the risk on a track like Lime Rock where most of the excursions will mean that you WILL hit something? There is nothing wrong with running with Stability Control on and still have a great learning experience. Turning it off for an Auto-X or Skid pad is a great idea.
How intrusive is stability control on GT4? Is it something that you turn fast laps with it on but not having to intervene? On my E46M3, its way too intrusive to run with it on. However, my understanding that on Porsche that you can still turn very fast laps with it on.
Another question that I have with respect to LRP...how much of the curbs can you use? I have never driven there but I don't see many cars in the videos that I have watched riding up on the inside curbs.
Another question that I have with respect to LRP...how much of the curbs can you use? I have never driven there but I don't see many cars in the videos that I have watched riding up on the inside curbs.
Frank gives a good summary of LRP curbs below. Some are flatter than others. The steep ones you don't want to ride up on (West Bend, Downhill).
No, the GT4 ESC is not near as intrusive as the BMW. The technology has improved substantially since then, with higher sampling rates and a better algorithm that allows more slip and movement before "coming in." Instead of an engine power "cut" in the BMW, the GT4 relies on a variety of stability measures including actuating rear brakes to "pull" the rear back in line. Let's just put it this way, in the Trophy East ClubSport East series, GT4 CS owners are required to run ESC...
#32
Thread Starter
Rennlist Member
Having been there myself, albeit with a Cayman S not a GT4, I agree 100% with Frank.
Going from a 944 to the Cayman I needed time to feel comfortable. When I got to the point where PSM was holding me back I turned it off and that was that.
Leave stability control on until you feel comfortable with the car on track. Skid pad and auto cross is a great way to learn your car without risk. Just don't use stability control as a crutch for too long and get some coaching.
The only track in the Northeast worse than LRP for lack of runoff and potential for damage is probably Palmer.
Going from a 944 to the Cayman I needed time to feel comfortable. When I got to the point where PSM was holding me back I turned it off and that was that.
Leave stability control on until you feel comfortable with the car on track. Skid pad and auto cross is a great way to learn your car without risk. Just don't use stability control as a crutch for too long and get some coaching.
The only track in the Northeast worse than LRP for lack of runoff and potential for damage is probably Palmer.
#33
Race Car
#34
Burning Brakes
I am not one to personally give advice, but I will simply relay some information I have heard from several professional coaches at the LRDC.
First, there was a GT4 at the LRDC track day just yesterday. There was also a discussion on gear changes that I was lucky enough to sit in on and the consensus among the LRDC pro-coaches was to stay in 3rd gear on No Name and to not shift to 4th in the GT4, but I don't think anyone had gotten hard data. Also, I have no idea how fast the driver is to whom they were giving this advice.
Second, your corner entry into Big Bend is not a constant G corner. I don't know if that is intentional or not. I do know I had a lesson with Doug Brown who is an instructor with SCDA and who runs their AX program and he teaches the line it appears you are driving. None the less, after my lesson with Doug Brown I asked Simon Kirkby about it and he said many folks have examined that line with data and it has a faster time to entry, but a slower time over all for Big Bend. Just in case it's unclear what I'm talking about, I'm talking about angling in from about the 6 panel to the corner entry on T1.
Anyways, like I said I am not giving any advice personally I'm just repeating what I was told or heard.
First, there was a GT4 at the LRDC track day just yesterday. There was also a discussion on gear changes that I was lucky enough to sit in on and the consensus among the LRDC pro-coaches was to stay in 3rd gear on No Name and to not shift to 4th in the GT4, but I don't think anyone had gotten hard data. Also, I have no idea how fast the driver is to whom they were giving this advice.
Second, your corner entry into Big Bend is not a constant G corner. I don't know if that is intentional or not. I do know I had a lesson with Doug Brown who is an instructor with SCDA and who runs their AX program and he teaches the line it appears you are driving. None the less, after my lesson with Doug Brown I asked Simon Kirkby about it and he said many folks have examined that line with data and it has a faster time to entry, but a slower time over all for Big Bend. Just in case it's unclear what I'm talking about, I'm talking about angling in from about the 6 panel to the corner entry on T1.
Anyways, like I said I am not giving any advice personally I'm just repeating what I was told or heard.
Last edited by JP66; 09-18-2016 at 01:57 PM.
#35
Burning Brakes
For what it's worth here's an interesting comparison. I take the traditional entry and worked hard with Peter Krause to make sure I am at 1G continuous at the entry to Big Bend and not leaving time after max braking for coasting. It would appear that this line is 1.4 seconds faster by the apex of the right hander. Improving that section alone could almost put you under 1:00.
Last edited by JP66; 09-18-2016 at 03:20 PM.
#36
Burning Brakes
And do not red line 3rd or 4th to stay in gear. Shift at ~7000 RPM. It is a) faster b) easier on the mechanical and c) faster.
If you find that in the GT4 that you are going too slow to make these shift points/gears work then you need to perfect your line going into both of those straights, if you line is perfect then you need to start getting to the throttle sooner and once you start getting to the throttle sooner you need to get deeper into the throttle sooner.
Last edited by Jenner; 09-18-2016 at 04:52 PM.
#37
Burning Brakes
I have to disagree with this. If you are not reaching 4th on no name and 5th on the main straight in the GT4 your exit speed from the corners before the straight are too slow.
And do not red line 3rd or 4th to stay in gear. Shift at ~7000 RPM. It is a) faster b) easier on the mechanical and c) faster.
If you find a GT4 that you are going too slow to make these shift points gears work you need to first perfect your line going into both of those straights, if you line is perfect then you need to start getting to the throttle sooner and once you start getting to the throttle sooner you need to get deeper into the throttle sooner.
And do not red line 3rd or 4th to stay in gear. Shift at ~7000 RPM. It is a) faster b) easier on the mechanical and c) faster.
If you find a GT4 that you are going too slow to make these shift points gears work you need to first perfect your line going into both of those straights, if you line is perfect then you need to start getting to the throttle sooner and once you start getting to the throttle sooner you need to get deeper into the throttle sooner.
I don't own a GT4 so can't run the test myself, but what I can say is that folks said the same about my R which hits red line and 103 in 3rd on No Name and that shifting to 4th cost .7 seconds per lap as tested with Jonathan Goring (a pro driver) at the wheel.
Second, based on Paradoc's video we are talking less than 2 seconds from when he shifts out of 3rd at 7300 RPM to when he slows for the entry to the UpHill. Based on his acceleration at full throttle in his video he might just touch red line for a micro second. The conventional wisdom told to me at Skippy school and again by Jonathan my coach is that a moment at Red Line is far superior to a shift. Maybe not better for the engine but better for speed.
Also the enty speed to NoName is limited by the G forces on the street tire that Paradoc is using. My data in the R on street tires shows that he is probably darn close to the limit where he is so I'm thinking it's not likely he will hit more than 67 on exit from the right hander so that means a top speed of 105 which should be possible in 3rd.
4th gear has a 1.1 gear ratio and 3rd has a 1.4 ratio. The difference in acceleration after the UpHill and West Bend should therefore be far higher in 3rd versus 4th.
Of course, the incredibly simple way to answer the question for oneself is to have a pro drive 2 laps each with a shift and no shift and see the difference in the data. Also I suspect a race prepped GT4 on slicks would most definitely need a shift, but I think a stock GT4 on street tires probably not so much.
Hopefully somebody with a GT4 out there will run the test for us
#38
Burning Brakes
But I did! That's my white GT4 next to my name...
I already did...
I was running 3rd and 4th gear to redline at the advice of "others."
PCA instructor with a GT4 suggested I try 4th and 5th and the next session I went out and did a sub minute lap. Not a pro, but it worked.
#39
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#40
Burning Brakes
#41
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#42
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For what it's worth here's an interesting comparison. I take the traditional entry and worked hard with Peter Krause to make sure I am at 1G continuous at the entry to Big Bend and not leaving time after max braking for coasting. It would appear that this line is 1.4 seconds faster by the apex of the right hander. Improving that section alone could almost put you under 1:00.
__________________
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-Peter Krause
www.peterkrause.net
www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
Specializing in Professional, Private Driver Performance Evaluation and Optimization
Consultation Available Remotely and at VIRginia International Raceway
#43
Thread Starter
Rennlist Member
For what it's worth here's an interesting comparison. I take the traditional entry and worked hard with Peter Krause to make sure I am at 1G continuous at the entry to Big Bend and not leaving time after max braking for coasting. It would appear that this line is 1.4 seconds faster by the apex of the right hander. Improving that section alone could almost put you under 1:00.
#44
Thread Starter
Rennlist Member
I am not one to personally give advice, but I will simply relay some information I have heard from several professional coaches at the LRDC.
First, there was a GT4 at the LRDC track day just yesterday. There was also a discussion on gear changes that I was lucky enough to sit in on and the consensus among the LRDC pro-coaches was to stay in 3rd gear on No Name and to not shift to 4th in the GT4, but I don't think anyone had gotten hard data. Also, I have no idea how fast the driver is to whom they were giving this advice.
Second, your corner entry into Big Bend is not a constant G corner. I don't know if that is intentional or not. I do know I had a lesson with Doug Brown who is an instructor with SCDA and who runs their AX program and he teaches the line it appears you are driving. None the less, after my lesson with Doug Brown I asked Simon Kirkby about it and he said many folks have examined that line with data and it has a faster time to entry, but a slower time over all for Big Bend. Just in case it's unclear what I'm talking about, I'm talking about angling in from about the 6 panel to the corner entry on T1.
Anyways, like I said I am not giving any advice personally I'm just repeating what I was told or heard.
First, there was a GT4 at the LRDC track day just yesterday. There was also a discussion on gear changes that I was lucky enough to sit in on and the consensus among the LRDC pro-coaches was to stay in 3rd gear on No Name and to not shift to 4th in the GT4, but I don't think anyone had gotten hard data. Also, I have no idea how fast the driver is to whom they were giving this advice.
Second, your corner entry into Big Bend is not a constant G corner. I don't know if that is intentional or not. I do know I had a lesson with Doug Brown who is an instructor with SCDA and who runs their AX program and he teaches the line it appears you are driving. None the less, after my lesson with Doug Brown I asked Simon Kirkby about it and he said many folks have examined that line with data and it has a faster time to entry, but a slower time over all for Big Bend. Just in case it's unclear what I'm talking about, I'm talking about angling in from about the 6 panel to the corner entry on T1.
Anyways, like I said I am not giving any advice personally I'm just repeating what I was told or heard.
I have to disagree with this. If you are not reaching 4th on no name and 5th on the main straight in the GT4 your exit speed from the corners before the straight are too slow.
And do not red line 3rd or 4th to stay in gear. Shift at ~7000 RPM. It is a) faster b) easier on the mechanical and c) faster.
If you find that in the GT4 that you are going too slow to make these shift points/gears work then you need to perfect your line going into both of those straights, if you line is perfect then you need to start getting to the throttle sooner and once you start getting to the throttle sooner you need to get deeper into the throttle sooner.
And do not red line 3rd or 4th to stay in gear. Shift at ~7000 RPM. It is a) faster b) easier on the mechanical and c) faster.
If you find that in the GT4 that you are going too slow to make these shift points/gears work then you need to perfect your line going into both of those straights, if you line is perfect then you need to start getting to the throttle sooner and once you start getting to the throttle sooner you need to get deeper into the throttle sooner.
On No-name straight, I ended up making the upshift to 4th most of the time prior to entering the Uphill. Same as on the front straight--I felt like I would be coasting a bit or braking too soon if I left it in 3rd near the redline prior to the Uphill braking zone. But then, as you point out, if you upshift, the car then feels a bit flat and out of its powerband as it climbs the Uphill in 4th. However, it does feel more secure in the scarier parts of the track (Uphill, West Bend) in 4th because the torque is more limited and it seems less likely to step out under power...
#45
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He contends the fastest corners are the most "valuable" in terms of lap time improvement.
I contend (and have massive amounts of data to support) the opposite.
My data supports the approach that:
A) it's FAR more injurious to to the lap time (which is just average speed over a lap's distance) if you lose a few miles per hour in the slow corner(s) than in the fast one(s) (proportionately more of the total speed measure, easier to raise the average MORE in the slow corners by a small change upward)
B) it's MUCH easier to realize a significant gain in slow(er) corners, ones that you spend proportionately a greater amount of time in (than the fast(er) corners)
C) it's easiest to pick up time at Lime Rock tightening up the transition from braking to steady state cornering/raising the average speed into and through Big Bend and slowing LESS for the Left Hander (as long as it doesn't inhibit throttle pickup)
D) there's the lowest increase in risk exposure to gain incremental speed in the slowest sections of the track.
For example, on a 53.3 second lap, from the point I hit the brakes on the straight to the point I hit the brakes into the Left Hander (my Big Bend sector), I spend 10.8 seconds in that area of the track.
From the time I hit the brakes for the Left Hander to the time my lat g builds turning right into Turn 4 (the right onto No Name), I spend 6.8 seconds in that sector (my Left Hander sector).
There is a lot of time to be mined from those two areas. Basically, I am spending 33% of my lap time in three corners and in 2000 ft of a 7800 foot long lap...
People fixate on lap times. If they just focused as much on improving the quality of every one of the dozens (or hundreds) of individual skill executions around the circuit, the lap time would come more easily. A LOT more easily.
Excellent work!
Last edited by ProCoach; 09-19-2016 at 08:19 AM. Reason: added distance of critical area versus whole lap distance