An eerily maniacal grin emanated from my buddy Steve Lobel’s face, giving me only a hint of what was to come. I arrived in the small burg of Canton, Ga., earlier that morning to see his car – recently retrieved from the tuner shop Forged Performance just down the road in Marietta, outside of Atlanta.
Lobel – a physician by trade and a true auto enthusiast at heart – had spent the last several years pining for, and finally achieving, the panacea of Subaru performance – a race-tuned Subaru WRX STi with a purported 600+ wheel horsepower.
His 2007 model STi was purchased new and used as a daily driver for quite some time, driven at some track days, and was the subject of many thought experiments as Lobel researched the best way to add and extract as much power as possible from the little flat-four turbo engine. Plans were made, changed and made again, and two shops and nearly two years later, Lobel collected his rally-bred and racing-inspired time attacker from the tuner – and he wanted me to take a look.
Now I sat next to him as he toggled the key and brought the raspy engine to life. What I was about to experience may best be demonstrated through interpretive dance – but since I’ve only a keyboard and mouse to use – I’ll ask that you use your imagination.
We putt-putted out of his hospital’s parking lot – careful to observe the hospital’s “quiet zone,” lest we disturb the patients. We were on our way to a highway that dissects the town to run the car up to a federally-mandated and completely legal 55 miles per hour. Clearly, for me to experience the true performance of such a beast, I was going to have to achieve double-nickel speed.
On our way to the Interstate, Lobel proudly shared details of the car’s build – the throng of parts acquired, and then expertly installed, modified or created specifically for his car. Words like “intake,” “turbo,” “cam” and “piston” were intermingled with “600” and “horsepower” and suggestions like “hang on” and “four wheel drift.”
I got the idea that what I was about to experience was going to be truly special, and I hoped against hope that the Michelin Pilot Sport 2 tires would work as advertised and glue that car to the road tight enough that our 55 mph road trip would be a safe and uneventful one. It turns out that I was only to be half right.
“Hang on,” Lobel commanded. In a flash, the on ramp disappeared, lost in a haze of turbo whine and the super fast snicking of gears – one after another after another.
Brrrwwwwzzzzpppp – Bang!
Bwzzzzzzpp – BANG!
Bwwzzzzpppp – BANG!
“There it is again”…BANG!
“Cut it out!” BANG!
The seatbelt pre-tensioners snatched me by the collarbone, keeping my large frame from being forced by Newton’s Laws into the floorboard, the dashboard or the back seat – which all felt possible simultaneously. My face slid off its mounting – the tendons and sticky bits that hold the skin and muscle together felt as if they had been ripped from their moorings. If only this could have been an out-of-body experience.
“Ready?”
BANG!
Lobel shouted above the din of the exhaust and mechanical cacophony underhood – the Subaru he was wheeling felt almost as if it would leave us in the road, sitting there, dumbfounded. As he grasped the wheel white-knuckled, I grasped the tiny plastic handle above the passenger side window frame.
We run through the gears once more, the turbos sounding at once as if they will come apart, and then shrieking like a frustrated screech owl.
BANG!
“Did that just happen?”
BANG!
I would have closed my eyes had I been able to.
BANG!
“Make it stop!”
“That was 100,” Steve plainly stated. “It just keeps pulling, doesn’t it?”
I laughed maniacally – trying desperately to work out a plausible story for the cops that were bound to pull us over, hook us up and jail us for such juvenile behavior – but I couldn’t. I was transfixed. I had driven everything from a Hyundai to a Bugatti and many things in between, but nothing – absolutely nothing – prepared me for the speed in which that little Subaru achieved triple-digit velocities. The stresses on engine, body and power train are immense – and the workload the tires must carry seems nearly infinite.
Tire choice in an application such as Lobel’s is an important part of the performance equation, and hooning around town comes a distant second to the true purpose of these highly-tuned machines: track work.
However, even though hard-tuned cars such as the Lobel Subaru are made to be driven in anger in autocross, rally or race venues, many owner/drivers also drive these beasts on the street – and this requires a dual purpose competition/DOT (Department of Transportation) street legal tire to run to and from the track. Performance heavyweights such as Michelin, Pirelli and BFGoodrich all have a stable of tire choices for road and track, as do Hankook, Yokohama, Kumho and Hoosier.
It is important to note that even though some competition tires carry the DOT street-legal designation, they are true track stars and not intended for full-on street duty, particularly in snow, ice or in the wet.
Lobel’s tire of choice for the early stages of his build was the Michelin Pilot Sport Cup, which features 6/32nds of tread depth. (Michelin recommend leaving the tire un-shaved for possible wet-track driving, but advised lap times and performance may improve slightly by shaving the tires for optimized dry performance to 4/32nds, according to Tire Rack.)
The Pilot Sport Cup is different from a normal UHP road tire in several key areas. It has two tread compounds – inner for wet traction and outer for dry handling – and features a large outer shoulder rib that enhances stability and steering response. Its BAZ (banded at zero) steel belt reinforcement is similar to the Pirelli P Zero design, featuring nylon zero degree overlay. The Pilot Sport Cups were a good match for Lobel’s modded Subaru, but when his power output increased to its current 600+ wheel horsepower rating, he looked for the next new thing and found it in Pirelli’s newest addition to the P Zero line of UHP and competition tires, the P Zero Trofeo.
Pirelli’s P Zero Trofeo is a DOT certified street legal tire that works on both road and track, as does the Pilot Sport Cup. Where the Trofeo differs from the PSC is in compound material. Pirelli now utilizes HAOF (highly aromatic oil-free) compounds in manufacturing the Trofeo.
The inner area of the Trofeo works on critical issues such as wet surface driving and aquaplaning, brake stresses and traction while the outer area has increased rigidity to cope with the cornering stresses of track driving, thanks to a tread pattern derived from rally asphalt applications. There is also up to a 10% increase in the size of the contact area when cornering, thanks to innovative grooving. This increase in contact patch means an increase of power to the ground for the Lobel Subaru – definitely a good thing.
It is unclear as to when enough power is enough power in Lobel’s case. As this is being written, Forged Performance in Marietta, Ga., is plying its tuning trade once more to the Subie – planning to extract even more horsepower from its Cosworth engine. Rumor has it that nitrous oxide is in the offing, and soon Lobel will have to change to a full-on, track-only competition tire. Too bad Formula 1 tires don’t come in 18-inch sizes.
