Larry Herman

Nothing personal, but if you are not picking up the throttle until after the apex, you are going to be quite slow. With a turbo car, you "typically" want to go as deep as possible, and turn-in hard, so that you take a later apex, and have a more gradual path past the apex and out to the track-out point. This will allow you to get right into the throttle after you turn-in and accelerate all the way past the apex and through the corner. This will give you the highest exit speed and make you faster down the straight. Sounds to me like you need to ride with someone who is doing it right so you can get a clearer picture of exactly what to do. That or spend an event or two in a very low HP car. That'll teach you about getting on the gas early!

ColorChange

Brian:

1) How far off are you from the club racer's times?

I am loathe to answer this because it feeds such a bad misconception that my personal ability has any bearing at all on the theory. It doesn’t. So, now that that is cleared up, the only time I have is a 1:37 on a brand new fully stock tt (except for moton shocks) at Gingerman. I can’t find comparable times in a tt but it certainly isn’t very quick.

2) I think you believe that in some turns, you are at the max speed that the car can carry (according to your DAS). Can you quantify how much time you are losing in the other turns?

That is a good question. Mathematically I should be able to do it but I haven’t tried. What I do is compare 20 times through the same turn. Usually I can find one time I went through pretty well. This establishes the fastest segment for that turn and then I can compare how I handled other turns.

3) Do you believe that the difference in those times is simply the lost time in those turns?

For example, let's say that you are 20 seconds off of the best club racer time. Let's say that you can account for 5 of those seconds due to turns that you could be taking quicker. The remaining 15 seconds suggest to me that you could be going quicker in all of the turns and that your assumption that you were at the limit was wrong.

Alternatively, let's say that you are only 5 seconds off the best time and you can account for all 5 of those seconds due to the slow turns. Then it might seem that you could make a strong point that your style of driving is the best.

I plan to have someone (as good and capable in my car as I can find) thrash my car at Putnam and compare that to my driving. I will then be able to show where I am fast and where I am slow, and where all the time comes from. With the DAS you can account for every 0.001 of a second by looking at segment times.

Bill:
Not an attack at you. It's just that I respect Jackie and would be shocked if he didn't trail brake. When Donahue was doing it, it was revolutionary for many, and that is one reason why he won so often. I still am under the impression that most racers knew about trail braking back then.

SundayDriver

I assume you are talking about combined g's. That is what every data system I have used calls it. If you mean Color Change's original definition of g-sum as an integral, then I do not agree that maximizing that means anything. Assuming we are talking about combined g's, then...

Yes, you will have to provide some trail braking to use all the available grip. But the concept of simply driving the FC does not provide an adequate model for going fast. If you have 1.0 g, then you can be on the edge with 1g of lat, 1 g of long, ~.7 of each or any number of other combinations. NOw I agree that you need to trail brake in order to drive that edge as the car transitions from braking to cornering, but that period is very short - it is as long as it takes the suspension to set, as far as I know. I've driven my Excursion tow vehicle on the track and it does not use all the corner to the apex to set. So while I agree that you need a short amount of trail braking to drive the edge of the FC, once that is done you have a choice as to whether you drive it by maximizing lat g's or use heavy trail braking at the expense of g's. The debate for me is whether or not heavy trail braking to the apex is faster in more than a few corners. I think not and have not seen any evidence that it is, bit I am listening.

Mark in Baltimore

I believe the person in question that Jackie Stewart referred to was Bob Bondurant.

Premier Motorsp

SundayDriver:

Gsum (for me) =SQR(latG+LongG). No integration.

When you enter a corner you must transition from decel to lateral. I think we agree on this point. It is faster to make this transition without leaving the edge of the friction circle. I think we agree on this as well.

In order to not leave the edge of the friction circle you have to smoothly trade decel for lateral in such a way that the G vector swings from 6 o'clock (pure decel) to 9 or 3 o'clock (pure lateral). I don't think the suspension response time has any bearing on this, other than what it forces the driver to do to remain on the edge of the friction circle.

I am pretty sure that optimally the point of max lateral G should be at the lowest speed in the corner. This should also occur when the Long G is zero.
(unlikely in the real world, but we are talking best-case-scenario, right?) Maybe someone can provide the math to back this up.

Anyway, if the lowest speed coincides with the highest lateral G, then the decel to that speed needs to be done in a such a way that Long G dwindles to zero in the longest possible time in order to have the highest average speed thru the entry phase.

I realize this is not very clear. It is the best I can do right now.

One other thing to remember: cornering creates a great deal of tire drag. This means you have decel automatically unless you are applying a lot of gas. Through the last 1/3 of the time from turn-in to apex, this drag may be enough to satisfy the friction circle's Long G requirement.

Chris Cervelli
Premier Motorsports

ColorChange

Larry: No problem and I agree with what you wrote. I didn’t communicate very well, I said near the apex. I am often on the throttle before the apex but what I am really asking is the method of using the throttle breaths to control rotation correct (fastest) or not?

Whoaa Chris! I hadn’t thought of that (Duh on my part). Awesome! And hell no will I try that right away unless my new brakes are great and I get comfortable filling out the fc in a hurry. So, it is fast and I should keep doing it, but eventually I will change to doing it with the brake release. Coooool! Boy will that make the neutral phase short. Thanks.

ColorChange

Agree 100% again Chris.

Brian P

This is a very good point. I know that there are some turns where I'm absolutely positive that I was off the brakes before turn-in, and then I look at the DAS and it tells me that I'm still slowing down while I go to the apex. If we rename trail-braking to trail-slowing, I think a few more people might agree with some of these premises. When you get enough decel from cornering, it can be real easy to overbrake the corner if you are also using the brakes.

ColorChange

Yes Brian, that is why people call it neutral throttle, not no throttle during the neutral phase of the turn (around the apex).

SundayDriver

I'll put my $0.02 in...
If your car is tail happy, then throttle is needed to keep it on the track. If it is neutral, then it may simply feel better and higher confidence = lower lap times.

I can tell you that in my case, as I was learing to drive the SRF, we kept making it more and more tail happy and I kept getting faster and faster. Then we backed if off and I was faster still. So what happened? We had really been training the driver to get on the throttle sooner which is what made me faster. I had to do that to control the tail but once I learned early throttle, I really didn't need all that oversteer. I suspect that what you are really experiencing is the same thing. You are getting on the power sooner and the car feels better under power so you are faster.

If a car is balanced, then there is no need for the weight to be moved to the rear. I hope that made some sense.

Larry Herman

Neutral phase of the turn??? That would be the time it takes me to get my foot off the brake and onto the gas. 99% of the time you are either braking hard or accelerating hard. That's what I do, and I am known for getting around pretty quickly.

You can physics this thing to death, but the longer you are at full throttle, the faster you will be. Plain and simple. I may be going a little slower at my maximum turn-in point (but I will still be generating maximum G forces) but I will quickly become faster as I am on the gas so much sooner than one who is feathering the throttle trying to maintain the highest constant speed through mid-corner.

Glen

Brian P, did You get the Boxster issue fixed? Never heard from You or Rick so I hope that solution worked out ok.?

ColorChange

Another way to think about trail braking is this. Is it ever faster to wait until you exit the turn completely before applying the throttle? That is what you are doing by not trail braking as the turn is kind of symmetrical (braking in is like accelerating out).

Larry
Not really. In some turns, large sweepers are the most obvious; the neutral phase of the turn can be quite long. Again, you are on the throttle, but not accelerating but neutral throttle, just maintaining your max lat g speed (or thereabouts). In general though, yes, the higher powered the car, the more correct you are.

Larry Herman

I'm not sure what you are missing in what I have written. The sooner you can floor the gas, the faster you will be. Maybe you are hung up on some strange definition of trail braking. I reiterate, in most cases, you brake up to the turn, lighten the pressure as you make a positive turn-in, and as the car rotates, you step down on the gas to set the tail, and then floor it, powering past the apex, out to the trackout point and down the straight. This is the way I (and all the fast guys I know) drive. It has been good enough to win 3 club races and finish on the podium 75% of the time in one of the largest, most competetive classes (F stock) in club racing.

ColorChange

Larry, the different way of thinking about trail braking was not intended for you. I think you definitely get it, and I agree with your description. We are on the same boat. My comment was to make it clear that in some turns the neutral phase is short, in others, it can be quite long (like the carousel at Road America).