Civic Vs Miata At NJMP Lightning

Published: October 29, 2013

Last weekend I drove the Civic I recently acquired at NJMP Lightning. Per the specs, Civic had slightly more power than the Miata and about 200 lbs less weight, and was running a smaller tire (205 vs 225) of a similar compound (R888 vs NT01). I was expecting Civic to turn lap times similar to those of Miata.

It was then with more than a bit of curiosity that I watched the lap timer indicate 1:21 as my best time in the Civic whereas I ran consistent 1:18 in the Miata. Time to go to the data to see where I was leaving time on the table.

I used the best lap from last event's only session as my reference lap. Despite transmission issues I ran a 1:18, so while it was definitely not the best I could do the time is a good indicator of where I should be. Comparison lap was the best lap from the second session on Sunday.

I started by looking at speed only, because speed graph is smoother than acceleration graphs and because it offers a lot of insight quickly.

Light blue is Miata speed, medium blue is Civic speed. What can we learn from this graph?

Turn 1

Significantly earlier braking point in turn 1 in the Civic. Then, significantly lower minimum speed in turn 1 - about 5 mph lower. In this case I was not using all of the available grip in the corner, essentially taking it too slowly. I know this because I consistently did not need to track out all the way at corner exit. The tracking out observation combined with the data make a very strong case that I should have been going through turn 1 faster.

Why was I not? Part of the reason was I did not see the track very well. I am too low in the car and the top of the steering wheel is at my eye level looking at the track. I was truly cresting blind.

The other part was I did not have complete confidence in my brakes. The pedal started most sessions quite hard but became spongy in short order. This is another aspect of the car I need to improve to go faster.

Note the different shapes of the speed curves - Civic curve bottoms at corner entry whereas Miata curve bottoms around the apex. In the Miata I was doing more trailbraking and bleeding speed off while turning in. In the Civic I braked more in the braking zone before entering the turn and was on power from the turn in point.

Turn 2

I lifted way earlier in the Civic.

It is hard to tell while driving whether you are lifting "early" in that turn. Looking at data spells the situation clearly: in the Civic I was off power way earlier than in the Miata.

The solution to this loss of time is more track time in the Civic which would increase my general confidence in the car.

Turn 3

This is a continuation from turn 2. I am still off power in either car, therefore speed curves are the same with Civic's one being slower.

Turn 4

I took turn 4 much slower in Civic than in Miata. You can see Miata speed flattening out around turn 4, whereas in the Civic I braked and accelerated.

The Civic felt unstable going faster; the car is actually quite tail-happy in high speed turns and in transitions, and I did not feel a lot of confidence in it sticking at higher speeds. Another issue that should be solved with more seat time in the car.

Separately from car balance I had a bit of a hard time controlling the steering in turn 4, because I was changing direction under significant lateral Gs. I am sitting pretty far from the steering wheel, and in turn 4 in particular this was obvious. Turn 4 is another corner where fixing the seating position would gain me speed and consequently lap time.

Turn 5

Looks like again I am lifting way earlier in the Civic. In turn 5 I did not at all feel like I was lifting early. Maybe "a little bit" but certainly not that much.

Turn 6

Not a turn in either car, but you can see the time Civic spends shifting with a street clutch and flywheel. You can see the Miata shift point as well, it is just past where Civic speed overtakes Miata speed, and Miata's shift is easily 1/3 of the time the Civic shift takes.

Speed on this straight confirms that Civic has a better power to weight ratio than Miata - coming out of turn 5 slower it achieves a higher speed by the braking zone in turn 7.

Another way to phrase this is I should probably not worry about gearing in Civic - it is not what is costing me lap time.

Turn 7

Civic again is earlier on the brakes than Miata.

On this lap Civic decelerates past the apex. It was experiencing some understeer in turn 7, and unless I started turn in early enough I had to wait to get on power to keep the car on track.

Turn 8

Civic catches Miata speed-wise again.

Lightbulb

Civic lifts earlier and spends more time off power.

The curve shapes are interesting however and suggest that Civic decelerates less off power than Miata. This is with both cars being near their respective redlines. Perhaps Civic's lower displacement accounts for this.

Both cars accelerate similarly on the main straight. Perhaps Miata is relatively better geared in higher gears, or has better aero (which would not surprise me as the Civic is very much a box).

Conclusions

To summarize the lap and make a plan of action:

  1. Brake later.
  2. Increase mid corner speeds.

Armed with this plan I went out for two more sessions and got my 1:21 time in the Civic down to a 1:19. This is what the speed graph looked like with the 1:19 lap added:

Dark blue is the best Civic lap.

What do we see here?

Turn 1

I now brake as late as I do in the Miata, and Civic apparently can brake harder. I still brake more in the Civic than I do in the Miata. I did not improve minimum corner speed significantly.

The takeaway here is you can move the braking points downtrack relying on braking consistency, but it is hard to improve mid corner speed without seeing the corner.

Turn 2

I am hesitating/experimenting, but I was able to at least increase my speed everywhere compared to the best lap from the second session.

Turn 3

Same situation as turn 2.

Turn 4

The speed curve is much flatter in turn 4 and much closer to the Miata curve which is great. I improved the outright speed a lot but much more remains to be done.

Turn 5

I take turn 5 faster than in Miata. I pretty much stopped braking and lift only momentarily there now.

This single corner tells me that Civic has, more or less, at least as much grip as Miata does. If I can match Miata's mid-corner speed in this turn, I should be able to do so in all of the other turns as well. My goal, then, is for the Civic to be faster than Miata in each corner on the track - and once that is achieved, for the Miata to be faster than the Civic. Repeat ad infinitum.

Turn 6

The exit speed of turn 5 is dictated by me fitting into the track, not by the apex speed. Therefore speeds through turn 6 remain the same. I could possibly go faster if I saw out of the car better while in turn 5.

Turn 7

I improved my braking slightly but it is nothing to write home about. However, I improved my mid corner speed to Miata level which is awesome. The flatness of the speed curve suggests that I now overslow for this turn, and also that I should try to run a slightly later apex in order to accelerate through the exit rather than maintaining speed to fit into the track.

Lightbulb

Huge entry speed improvement, on par with Miata now. Then I brake/lift more and partially throw the gains away. Need to keep working on this corner.

Conclusions

Here is my action plan for next year:

  1. Fix seating position.
  2. Fix brake pedal sponginess.
  3. Carry more mid corner speed.
  4. Brake later.
  5. Beat Miata lap times. :-)

Tagged: data analysis