The phrase “Wider is Better” has a connotation of being a bit of a joke since it was used as a cheesy advertising catch phrase for a vehicle few people thought was “better” regardless of it’s real or perceived wide stance. Regardless of the connotation, it still poses a real question: Is wider better?
Chris and I attended a recent Driver’s Edge event at Texas World Speedway with my American Iron car. On hand with us was a Race Technology DL1 data acquisition system, a fresh set of shaved Toyos and some new 1” thick spacers that would get the front track width of my car right to the new 73” width allowed by the 2008 AI rules. Since I have gotten some questions lately about the effect of track width on lap times, the conditions seemed ripe for a bit of testing.
Saturday morning at the track started out a bit foggy but once it cleared I went out for a session to scrub in the tires and get them up to temp so the hot tire pressures could be more accurately set.
I sent Chris out for a similar reconnaissance run and he came back reporting a setup not to his liking. The last tuning done on the car was with very worn tires and it’s not surprising the car was reacting differently on the fresh rubber. After a few adjustments to the car, it was ready for some testing.
I told Chris that we were going to do some back to back comparison testing but I didn’t tell him what changes I was going to make to the car. In an effort to keep the testing consistent between runs Chris made it his quest to line up several like sized passengers. He somehow managed an amazing run of short and petite females for the task despite some complaints by them of being considered control “ballast.” Actually, David Love managed to sneak into the passenger seat on one run. While he didn’t upset the weight factor too badly, he blew the attractiveness ratio all to hell.
The baseline run was with 1” thick spacers in front and no spacers in the rear. The narrow test run was with no spacers front or rear (2” narrower in front). On the subjective front, Chris thought the handling was pretty good for the baseline run but came in raving about how much better the handling was with the narrow setup. Really??? That wasn’t what I was thinking his reaction was going to be. Chris was also pretty shocked when I told him what I had done to the car. Subsequent test runs were with the 1” spacers in the front and ¼” or ½” spacers in the rear trying to get closer to the same front/rear width ratios that made the car “handle” so well. I would have liked to add more to the rear but fender rub prevented it.
So the narrow setup made the car “handle” better but did it make it “faster?” The data acquisition would have to answer that question.
Unlike my previous aerodynamic analysis where the differences in the data were significant enough that I used detailed data specifically from representative corners, the data from this analysis was subtle enough that the differences tended to fall into the noise. Only by accumulating full lap data did a pattern between the different setups emerge.
By looking at the best lap time from each representative session we find that the best lap time from the narrow setup was a 1:58.16 while the wider setups had best session lap times of 1:57.64, 1:57.59, and 1:57.67. This shows about a half second gain by going a full 2” wider.
Looking at the lap spreads from above might lead one to believe that Chris really isn’t human. Looking closer at the data, however, shows that there is more variability between the different laps than the above numbers tend to show. It’s about impossible (even for Chris) to get everything just right for a complete lap. There is always going to be a lap where one section was done really well while another lap excelled in a different section. The cool part about data acquisition is that you can break up the track into several different parts to gain insight into these kinds of things. From this, you can calculate a theoretical best lap time using all the sections that you got just right. I’ve attached a picture of the track showing the different sections I used for this analysis.
To validate the above data, we can take a more restrictive look at the data by only using Saturday’s valid sessions and try to reduce driver variability by looking only at theoretical best lap times for each session. For the narrow setup we get a best theoretical lap time of 1:57.17. The wider track width Saturday sessions have best theoretical session times of 1:56.58 and 1:56.44. Again, we find a variance in the ½ second range.
Anyway, a 2” difference in track is pretty significant. Even with that, the data shows the benefit of a wider track is small but real. Fortunately, for this modification, it’s a lot easier and cheaper for the reader to test on their own than the aero stuff I posted earlier. That’s assuming fender clearance issues aren’t precluding you from adding spacers…
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