paradocs98

Agreed.

I'm still learning the GT4, but my sense is that it's way less intrusive than those systems on previous generations of cars--Peter confirms this below. It was fairly intrusive on my E90 M3, severely cutting power, but doesn't seem to do that on the GT4. I was able to get significantly loose (whether intentional or not) in Big Bend and the Left-hander without it intervening. The one time it obviously intervened is when I overcooked the throttle application in the Left-hander and would have had a serious tank-slapper.

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).

That is very interesting. I'm assuming the programming on the ClubSport cars is such that it allows for even more sliding...

paradocs98

Yep. I think the West coast guys sometimes don't appreciate the limited runoff of places like LRP and the Glen.

winders

Ever hear of Sears Point (Sonoma Raceway)?

JP66

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.

JP66

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.

Jenner

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.

JP66

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

Jenner

Perhaps you missed this in the very first thread of this topic...

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.

hf1

What tires?

Jenner

DOT Street tires...19" Bridgestone RE-71Rs on OZ 19x8.5" & 19x10"
(19" wheel/tire combo is heavier than stock 20" wheels/tire combo)

Stock brakes with lines and fluid
Factory aero settings on high downforce.
Front rollbar full soft, rear full stiff.

hf1

Good work!

ProCoach

^^This^^

paradocs98

Interesting, and echoes what Frank tells me--the time to be made up is in the slower parts of the course (Big Bend, Left-hander).

paradocs98

I was definitely debating this myself. By the start-finish, I was approaching redline in 4th quickly. When I shifted up to 5th and tried to stay on the throttle a bit deeper into the T1 braking zone, it was a bit busy having to do a 5th-4th and 4th-3rd downshift in quick succession. So I was staying in 4th, coming out of the throttle early and probably coasting a bit, then braking too soon for T1. Likely time lost there. Especially if I get faster coming out of the Downhill, I'll be carrying more speed on the front straight and the upshift to 5th will definitely be necessary.
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...

ProCoach

Ross Bentley and I have debated this ever since day one of our friendship (and shared dinners, not a few glasses of wine!).

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!