1997 Mazda MX-5 Miata: How The Grip Stacks Up
March 15, 2011
Perspective. That's something I neglected to include with Project Miata's most recent round of performance testing.
Like, for example, how it measures up in terms of outright grip.
Beyond the jump is a list of the top fifteen grippiest cars we've tested in the past four years. The results might surprise you.
Lat. Accel (g) Model
1.02 2010 Chevrolet Corvette ZR1
1.01 1997 Mazda MX-5 Miata; Project Miata
1.00 2011 Chevrolet Corvette Z06
0.99 2011 Porsche Boxster Spyder
0.99 2010 Porsche 911 GT3
0.99 2008 Mitsubishi Lancer Evolution X
0.99 2008 Porsche 911 GT2
0.97 2011 Audi R8 5.2 quattro Spyder
0.97 2011 Ford Shelby GT500
0.97 2010 Porsche 911 Turbo
0.96 2011 Porsche 911 Carrera S Convertible
0.96 2010 Chevrolet Corvette GS Coupe
0.96 2010 Porsche Panamera 4S
0.96 2009 Nissan GT-R Premium
0.96 2008 Lotus Elise SC
Note that the Porsche GT2 and GT3 use R-compound tires. Project Miata is on traditional street tires.
Also, we've had a few cars produce higher numbers at a facility other than our usual testing site -- for example a ZR1 that produced 1.10 g and a GT-R Spec V that turned 1.11g. The list above shows new production cars all tested at the same site.
Now For Some Geeky Background On The Skid Pad
We use a 200-foot diameter skid pad. It's flat asphalt. It's not perfect -- there are paint lines and probably some seam sealer here and there on the surface -- but it is consistent. Surface temperatures, too, don't vary much. You won't see 30-degree temperature swings; Southern California is good like that.
Every car is run clockwise and then counter-clockwise, timed, and the results averaged. This always results in a less-impressive result than the instantaneous grip most tires are capable of briefly generating.
Often, the first run in each direction is the quickest. Subsequent orbits usually suffer since the heat liberated at the tire-road interface adversely affects their grip. It's rare to have to make more than two runs in each direction, and that's with alternating the direction each time to keep the tire temperatures in check.
The driver keeps the inside tire on the line all the way around the skid pad, and the "lap" time is measured. We use 103-foot radius for calculation purposes as that's roughly where the centerline of each car is located as it arcs around.
All cars, including Project Miata's most recent test, are tested with a full tank of fuel and all ancillary equipment in place unless specified otherwise. That includes a jack and spare tire or tire inflator kit, blowup doll or what have you.
More Grip? For Reals?
Project Miata could be set to a lower ride height and likely generate even more grip. However, this would eat into its street livability -- its current ride height of 4.75" front and 5.00" rear as measured at the pinch rails is about a half-inch higher than what you'd want on the track, and this, in turn, limits the amount of front camber that can dialed in. As it sits today Project Miata has -2.1 degrees front and -1.9 degrees rear camber.
Gaining additional negative camber while retaining the current ride height (which I like) would require offset control arm bushings. Perhaps a project for another day.
Also, a diet wouldn't hurt. For the car, I mean -- I'm a wall of muscle. A 2,344-pound first generation Miata like this one is something of a plumper in the context of track-driven examples. Some targeted weight reduction is in order, I'd say, keeping in mind that it's a dual-purpose car. Meaning the a/c stays.
Jason Kavanagh, Engineering Editor @ 130,xxx miles.