Palmer Motorsports Park 2: Miata 1.6 Vs 1.8 Data Analysis

Published: September 8, 2015

On the Labor Day weekend I made a trip to Palmer Motorsports Park with Metro NY PCA. The event was on Friday and Saturday, I attended Saturday only due to work commitments. I brought my naturally aspirated 1999 Miata and I thought it would be a good idea to compare the best lap this weekend to the best lap I ran at Palmer previously - in a stock 1.6 Miata on street tires.

Track

The track layout has not changed since May when I was last at Palmer, however there is now a dip before turn 11 that is insignificant when taken at leisury pace and quite unsettling when taken at speed.

The pavement in turn 6 seems to have gotten slicker. There were two distinct grip loss spots, one shortly before the apex and one right before the crown after the apex. It is possible that the loss of grip around grown has to do with the stiffer suspension of the Miata I was driving this time, although many tracks are crowned and this transition was much more slippery than I am used to elsewhere.

Attendance

The event was well attended, but it was never crowded. There were few trains and those worked themselves out quite quickly.

I was able to put down a single flying lap after starting at the head of the pack in an advanced/instructor session. Unfortunately right after I passed start/finish the intermittent power issue I have been having came on. The flying lap was a 1:50, and the only lap I have in the 1:50 range. I ran the rest of the day short shifting to keep the car cooler, and while that did not yield a lower lap time I did find some interesting insights from those slightly less aggressive laps.

Street NA6 Vs Track NB1

Last time I was at Palmer I put down a best of 2:01 in a stock 1.6 Miata on street tires (Bridgestone Potenza RE-11a). This time I was driving my white 99 Miata on Toyo RR, rather worn 225/45-15 in the front and about half worn 225/50-15 in the rear. I hoped to be faster everywhere in the NB1 compared to the NA6.

NB8, surprisingly, felt too stiff in places. Turn 14, in particular, has enough camber change in the track surface that NB8 struggled to keep all tires planted into the pavement. Entry into turn 6 and transitioning from off camber onto on camber parts of the surface were also tricky.

Turn 1 in NB8 felt bumpy, to the point of losing front end grip resulting in significant understeer. The tip on the entry into turn 11 was very noticeable and somewhat concerninng too.

Overall though NB8 had reasonable grip on the course. I am looking forward to running Palmer with new tires to see how much of a difference they would make, and I think I will soften the suspension next time I visit.

Turn By Turn

Turn 1 shows the horsepower difference between the cars - NB8 achieves a top speed of nearly 110 mph while NA6 only musters 94 mph. NB8 shows off its superior grip in the braking zone but then gives up some apex speed to NA6. NB8 in turn 1 is skating on the bumps in the pavement which required a steering correction and delayed throttle application. With a softer suspension and perhaps better front tires, NB8 should pick up a few miles per hour at the apex of turn 1.

Both cars take turns 2 and 3 under full throttle, although the ride in the NB8 is a little more exciting.

Turn 4 is a non-event in both cars.

Turn 5 situation is interesting because while driving the NB8 I felt that I was taking a wide line - certainly wider than my NA6 line, and data suggests that NB8 carried much more speed deeper into the corner which would generally suggest a shallower, earlier entry. I need to review video of both laps to gain a better understanding of what happened.

Both cars exit turn 6 under full power which was a more difficult feat to achieve in the NB8 than in the NA6, largely due to NB8's suspension stiffness.

Turn 7 features what looks like light braking in the NB8. I stopped braking there later in the day, but even with 115 whp in the NB8 turn 7 becomes seemingly impossible to drive under full throttle. Even so, NB8 is faster than NA6 everywhere in turn 7.

In turn 8 NB8 starts to accelerate much earlier with corresponding gains until turn 10. I think the much higher grip of NB8 accounts for most of the difference, but taking advantage of the extra banking in turn 8 finishes out the package. Turn 8 in the NB8 is quite fun, whereas in NA6 it's somewhat frustrating - largely due to grip limits of NA6's street tires.

In turn 10 NB8 shines again with its higher grip level - we are looking at a 6 mph minimum speed difference. As with turn 8, I found a better line which in turn 10 involves a later still apex, aiming at the end of the trees rather than at the end of the stone embankment past the corner station. With the later apex, added tire grip and just the right amount of trailbraking to tie everything together turn 10 in NB8 becomes a thing of beauty.

NB8 carries more speed through turn 11, which is not unexpected, and brakes harder in turn 12 which again is reasonable. NB8 gives up a couple miles per hour in turn 13 to guarantee solid exit; with a bit more track time I should be able to bring up NB8's minimum speed in turn 13 to above NA6's level.

Main straight is just a drag race, although NB8 speed trace is surprisingly choppy, or perhaps that is when I lost power in 5th gear. What is interesting about the main straight is that even with the possible power loss I crossed start/finish 1 mph faster than on the preceding lap. A 1:49 lap time should thus be rather easily obtainable in the NB8 as it was configured, with 1:48 or even 1:47 likely reachable with softer suspension, followed by 1:46 on better or 1:45 on new tires.

Bonus Round - Short Shifting

How much of a difference does short shifting make? NB8 was losing power on the straights if it was wound out to the redline in each gear, hence I decided to keep the car off the redline to get more track time. I also caught traffic which made clean laps impossible. Most of the laps in the higher gear mode were in the 1:52 range, but a couple were in the 1:51s. Below is a speed trace of the lowest 1:51 lap overlaid on the 1:50 lap:

The first, and obvious, observation is that the car only lost half a second of lap time. On many straights the difference in terminal velocity was within 2 mph, with the biggest difference being in turns 3-4 (uphill) where I ran in 6th gear which cost me 4 mph.

What is less obvious - and arguably more interesting - is that the car took many corners faster in the higher geared lap. Turns 1, 8 and 13 had higher minimum speeds in the higher gear lap. I attribute this partially to me actively working on running later apexes in those corners and generally cleaning up my lines and partially to me devoting more attention to the line and less to shifting and which gear I was in.

Looking at the realtime delta (yellow/orange traces on the bottom) it is quite amazing how much time the higher geared lap makes up in the corners over the lower geared lap.

The takeaway here is that for novice drivers, or drivers learning a new track, it is counterproductive to use lower gears - the gain in torque is rather small but having one's brain occupied by shifting in addition to learning the line really prolongs the time it takes to learn the line, and hence become a fast driver

Finally, looking at both NB8 laps and the best NA6 lap, even without winding the car out to the redline and taking it somewhat easy in the corners NB8 still beats NA6 everywhere on the track in speed (this makes more sense if we recall that NB8 with short shifts achieved higher minimum corner speeds but did not give up that much of terminal straightaway speed):

Tagged: data analysis