Overly tail-happy, but in a different way was the S2000, still shod in the original A048 Advan tires from when it was shipped over in '05. Since then, the rubber had competed in Super Street's Time Attack and suffered unknown abuse while traveling the country on the Hot Import Nights tour for a year. The TEIN suspension that probably worked well when the tires were sticky was now overloading the spent tires, causing them to break loose on the bumps. Fortunately, the S2000's communicative steering made catching the slides a piece of cake. Telemetry showed this car to be the least stable of all the closed-wheel cars. But still, the lightweight, downforce-producing body panels allowed the car to rocket through Turn Two the fastest of them as well.
In contrast, the Works Evo and Hasport Integra sailed butter-smooth through the segment. Their average gs and peak gs were only off by 0.04 and 0.02, respectively. Bernardo Martinez allowed me to take his Integra out for a few laps after testing. Between the suspension and practical sedan aerodynamic tuning, and the power delivery of the K24 swap, the car was an absolute pleasure to drive. It easily set the fastest lap time of the closed-wheel cars and had even more in it, if needed.
If we had called it a day at this point, we could have claimed that our highly tuned sport compacts were the g masters. But then the formula cars went out and decimated our silly field of 'racers'. Joiner tore through Turn Two, pulling an average of 1.64g in the FW08C. Then Hughes whipped through even faster in the Pro Formula Mazda. Our data acquisition couldn't record the gs from that car, so Chen hacked into their Motec system for an explanation as to how the thing went so fast. That system showed the car running through Turn Two at close to 2g. It also indicated that the car was producing 0.51g of downforce at the end of the front straight.
Our little Superkart, which managed to hop and skip its way though Turn Two, clocked an unconfirmed 2.87g spike. Why unconfirmed? Because the telemetry's accelerometer was in the midst of getting its brains bashed out, buried somewhere underneath the radiator inside the sidepod. Some of our cars had nice aero, but nothing that's going to pull like that.
In the end, we proved that our typical test cars will out-corner pretty much anything you'll find on the street, but to no surprise, they don't come anywhere near a fully race-prepped formula car. We especially have to thank Erich Joiner for bringing out his beautiful Monaco GP-winning race car, even if he was babying it a bit to protect his investment and our egos. To give you some idea of what those cars could do in their day, future world champion Nigel Mansell set the Willow Springs lap record in 1982 while testing his John Player Special Lotus F1. On our day, Hughes ran a fastest time of 1:17.558, maybe a new Pro Formula Mazda record. Twenty-five years earlier, Mansell clocked 1:06.300. Just before stuffing it into the embankment on the outside of Turn Four.
On a banked corner, the reaction...
On a banked corner, the reaction to the car's weight (blue arrows) is doing part of the work of holding the car in the corner. Add the varying amounts of friction (red arrows) provided from each tire at the limits of traction, and the total lateral forces (green arrow) pushing the car into the turn will increase with the banking angle. In order for the centrifugal force pushing the car out of the turn to now be equal to the forces pushing the car into the turn, you'd have to go around the bank faster (for the nit-picking physics nerds out there, this obviously isn't a proper free body diagram).
G = Gravity
While sheer lateral grip doesn't necessarily equate to a fast car on track, our 200-foot skidpad is still a good measure of most street cars' amount of stick. It's an average of the lateral grip any car generates, calculated from the time it takes to complete a level circle, 200 feet in diameter, in both directions.
We're always striving to break 1g in our street cars. No small feat, considering the tires are supporting the equivalent of the car's weight sideways. Put in perspective, most cars generate just a hair over 1g at peak straight-line braking deceleration, and few can exceed the magic number in acceleration.
Even in all-wheel-drive cars, with all four wheels generating friction to launch, it's harder to accelerate the vehicle in a straight line than it is to hold the car from going sideways. Part of it has to do with the fact that a tire's traction circle is slightly elliptical, since the tire contact patch is wider than it is tall. More critical, however, is weight transfer. Friction is as much a function of the tire itself as the weight that it's supporting. With less weight on the front tire in a launch, less overall friction or grip is available. In the sideways scenario, while there's still weight transfer, a well-sorted suspension will keep weight on all four tires much more than in straight-line acceleration. The forces trying to overpower tire grip and push a car out of a turn are also more powerful than the force an engine can supply to push a car forward.
But the skidpad isn't the ultimate judge of lateral grip. Real race cars suffer mid-throttle asphyxiation and a miserable understeering death on such a small loop where there is no aero grip. A fast constant-radius turn separates the sticky cars from the quick ones. That's exactly what we found in Turn Two at Willow Springs International Raceway in Rosamond, California. The track is considered the fastest in the West, where street cars can see speeds of up to 110mph down the front and back straights. Turn Two's slightly banked profile and large radius gives plenty of room and speed to see just how much difference downforce makes in increasing lateral grip.
For reference, we brought out a bone stock Mazda RX-8, which for our intents and purposes, has negligible aero grip or lift. It averaged 85mph and 1.03g through the turn, compared to the 0.92g it pulled on the skidpad. That extra 0.09g comes just from the higher speed and road camber.
Turn Two averages a couple degrees of banking, which adds to the equation. Normally, on a flat turn, the centrifugal acceleration, (or lateral g) acting on the car is equal to the total lateral friction force of all the tires trying to keep the car from sliding out of the turn. On an angled banking corner, Newton's equal and opposite reaction force to the car's weight, which normally has no effect laterally, now contributes to pushing the car back into the turn, along with friction forces. So at the maximum threshold of tire grip, there's more force available to push the car back into the turn than on level ground. To bring everything back into balance, a car would have to travel faster through the banked turn and generate more centrifugal force. This is why you can round a banked onramp a lot faster than a flat one. -Jay Chen
From Zero to Hero: The 1g Challenge
Getting a car with any semblance of sportiness to pull a g is old news. So we went the opposite way in search of the elusive 1g: find the biggest turd we could get our hands on and see if we can get it to support its own weight sideways. Ironically, finding a reasonable candidate wasn't so easy in a sea of modern high-performance cars. It had to be horrid enough to make the challenge worthwhile, but at the same time new and popular enough that manufacturers are willing to actually make parts for it. Our managing editor's Datsun F10 and our editor's minivan came to mind as potential sacrifices to the skidpad, but we couldn't find anyone sufficiently odd making parts that lend any handling advantage.
We settled on a not-so-sporty, but certainly compact 2007 Toyota Yaris S sedan. It's the ideal econobox platform, with probably the least guts of any car we can think of. Just the kind of thing the Japanese would consider cool enough to be turned into a spec race car-the Vitz-precisely where we'll find our suspension bits. So the plan was to baseline the Yaris sedan, bring out the parts we'd need, and make changes on the spot to have the Yaris break the magical 1g barrier.
TEIN's crew came out to the track with a set of their unfortunately named Super Street coilovers developed from their Yaris hatch race car. The simple bolt-on suspension and minor changes to the factory alignment brought the Yaris from a pathetic 0.76g to an impressive 0.85g on the 200-foot skidpad. All with just springs, dampers and no anti-roll bars, in typical Japanese fashion.
Obviously, no amount of suspension would make the Yaris' stock grocery-run mommy tires break a g. So we called up the wheel and tire experts at Tire Rack to find the right pair of shoes. We weren't surprised that no one had any idea about what fits a Yaris, but that's what's so cool about Tire Rack. If they don't know, they'll find out. Even after fitting a set of 15x7 Enkei RPF1 with 225/50R15 Hoosier A6 compound tires in a computer simulation, Tire Rack went to the extreme of bringing in a stock Yaris sedan into their headquarters in South Bend, Indiana, to make sure the set-up worked with no interference issues regarding the stock suspension and chassis for the entire range of suspension travel. They even made sure there was enough clearance for the TEIN coilover suspension we were planning to stuff in. Special treatment, we thought, but it's a service they perform for any of their customers.
With the Hoosier autocross A6 compound and cheater slick tread design, our little Yaris went out and pulled off 1.05g. Something few of our projects cars can claim and enough to beat even the phenomenal new 997 Porsche 911 Turbo. So what did we prove? Two things: a little tire goes a long way and, while you may not be able to make a turd go fast, it's pretty easy to make one stick. -JC
Williams Type FW08C
Not to be confused with the six-wheeled FW-08B that never saw a racetrack, the car you see here competed in Formula One in 1982 and 1983, helping the original 'Flying Finn' Keke Rosberg secure the 1982 drivers championship, despite just one win at Dijon over the course of the season.
The 1982 French Grand Prix was a hard-earned victory for Rosberg. The Cosworth engine was said to be more than 120hp down on the turbocharged competition Renault and Ferrari campaigned. Because the 3.0-liter V8 lacked the oomph to overpower heavy downforce, it had to be dialed out. As a result, the Goodyear rubber tended to spin into narrower doughnuts at high speed. According to the Finn, the car's deficiencies simply meant he'd have to take "massive risks" on faster tracks. The cars strong suit, predictably enough, was on tighter tracks where a lot of downforce could be used while not sacrificing top speed. Rosberg proved this in 1983 with a win at Monaco, albeit mostly due to a lucky tire choice.
Uniquely, the car is equipped with a Hewland six-speed transmission, installed to help deal with the turbocharged competition. As Frank Williams puts it: "The idea was that the driver could latch onto a turbo car in a corner in fifth gear and peak out of the corner with another gear still in hand to hold the turbo car until the end of the straight."
Avid F1 fans may note the absence of some of its original livery. The car is devoid of its most important historical sponsor, Bin Laden. You read that right-it was the father of a global terror who paid for this car to rocket around the world's race tracks. Now owned by Erich Joiner and campaigned in many illustrious rich-guy racing series, the reviled family name was removed, but the Saudia stickers are retained-like building a Messerschmitt model without the swastikas.
The car still gets to stretch its legs on a regular basis. Crew chief Thomas Griffith sees to it the car is kept in tip-top condition and offered his expertise here. Catch up with Joiner and his storied car at www.historicgrandprix.com. -James Tate