Z4 M Part 7
This is it, the grand finale. An all-out track shoot-out with three completely different, yet wisely modified modern enthusiast cars. Each fit perfectly into the "OEM Plus" category. We took our Project Cayman X51 and Project Z4 M to the track for direct comparison to an intelligently modified Porsche 911 (997) Carrera S to wrap up two exciting project car series in one wild swing.
Let's set the stage: In this writer's humble opinion, the Porsche 911 is the benchmark to which all other sports cars are compared. The original plan was to test our completed Project Cayman X51 with its big brother, the 997 S. Just for fun, we decided to bring Project Z4 M into the mix, as its performance progression over the past two years has been extremely successful. Thus, we end up with three high quality machines, and each with different engine/chassis layouts. How close will this contest be? And which one will reign supreme?
On the same day, with the same weather conditions, same track, same driven line, same test driver, same data measuring equipment, and all vehicles on R-compound tires, we go about the task of blasting each vehicle around Race City Motorsport Park's two-mile, 11-turn road course in Calgary, Alberta (unfortunately, the 'Ring wasn't within our budget). Using the Traqmate GPS acquisition system we were able to collect a lot of hard data during our test day: lap times, velocity/distance data, and lateral/longitudinal g-force data, all in order to make some accurate quantitative assessments regarding our contestants.
The Test Driver (a.k.a. The Bloke)
Our hot shoe/test driver for this event is former Australian Porsche Cup driver, Steven Tory. We know him by many names, "Sideways," "Sparky," and "The Bloke" to name a few-we'll stick with the latter and keep the other unmentionables to ourselves. The Bloke was instructed to drive each car with the same level of anger, avoid the curbs, and, most importantly, keep them off the concrete walls. And he did just that... good on ya, mate.
2006.5 BMW Z4 M Coupe
Front engine, rear drive
Weight Bias: 50:50
Curb Weight: 3,240 lb
3.2-liter inline six, stock power 330 hp
Full Supersprint exhaust (step headers, metallic cats, X-pipe, Power Loop mufflers), K&N panel filter with OEM charcoal unit removed, OEM software
365 hp (dyno proven)
Six-speed manual, OEM LSD
KW Suspensions V3 coilovers, TC Kline camber plates with custom 3mm spacer, OEM anti-roll bars
Brembo GT assemblies with 355mm/345mm two-piece rotors (f/r)
Forgeline ZX3-R, 9x18, 10x18 (f/r)
Nitto NT01 R-compound, 245/40, 275/35 (f/r)
$49,000 + $21,000 (mods)= $70,000
The underdog -BMW Z4 M CoupeIn Part 1 of the project series, we compared the Z4 M Coupe with the Porsche Cayman S. However, with a factory horsepower rating of 330 hp, it is entirely possible that BMW had its sights set on the entry-level 911, with the 997 Carrera and 997 Carrera S rated at 325 and 355 hp, respectively. So perhaps the bargain-priced M Coupe is not at all out of its league here. In addition, Project Z4 M has been subjected to several well-executed modifications.
For the price, this car absolutely rocks.
The contender-Porsche Cayman SThe original plan for this project car was to de-throne the mighty 997 S and encroach into GT3 territory with no regard for time or cost. Our "science project," as we affectionately refer to it, is now blessed with a 997.1S X51 crate engine and a menagerie of other track-ready bits and pieces. The result is quite spectacular, but is it enough?
2008 Porsche Cayman s
Mid engine, rear drive
Weight Bias: 46:54
Curb Weight: 3,150 lb
Three-spoke steering wheel, red taillights, bi-xenon headlights, Sport Chrono package, self-dimming mirrors
Transplanted 3.8-liter X51 flat six; stock power 381 hp
Custom headers and cats, Supersprint cat-back exhaust with Power Loop mufflers, custom intake with K&N cone filter, custom REVO software
400 hp (est.)
Six-speed manual, B&M short shift kit, HP Sachs clutch
KW Suspensions V3 coilovers, camber plates, Tarrett Engineering anti-roll bars, links, tie rods, rear toe control arms
OEM assemblies with Goodrich stainless lines
Forgeline ZX3-R, 9x18, 10x18 (f/r)
Nitto NT01 R-compound, 245/40, 275/35 (f/r)
TechArt front spoiler, SpeedArt rear spoiler
996 Euro GT3 Seats, Scroth six-point harness, Cantrell Motorsport full roll bar
$65,000 + $40,000 (mods)= $105,000
Hard Numbers and Impressions
After The Bloke finished with each car, I took each out for back-to-back track sessions as well. I was then able to go through Traqmate GPS data and discuss vehicle performance with him. Table 1 summarizes the results of his hot lap sessions.
Each car had particular performance idiosyncrasies which we'll look at below, but let's cut to the chase. According to Table 1, the 997 S was the clear winner in this real-world numbers contest. It won all categories except Peak Speed. We'll start the analysis by seeing what The Bloke had to say:
"Driving three vehicles in anger, back to back to back, is a great experience. It really highlights how similar, and different, three cars can be. Once at speed, and one starts to push each car toward their limits, some clear differences appear. There becomes a gap in the ease-of-use factor. However, this did not diminish any of the fun factor.
"The Z4 M Coupe is a much more involved drive, needing full concentration at all times when driven at the limit; it is always very rewarding when you get it right.
"My overall impressions of the Cayman were very favorable; the car felt light, well damped, and most of all, very fast. After the session I felt that it was easily the fastest car of the three. However, the GPS telemetry told a different story.
"Overall, the 997 S was the easiest car to drive fast. It remained balanced, with very minor corrections needed to keep the car on line. At no time did the feeling of an infamous rear engine vehicle come to mind."
The numbers tell us that both Project Z4M and Project Cayman X51 were fairly defeated in our controlled performance test. But let me point out that each of these cars have come a long way up the performance ladder to compete at this level. Also note that our "OEM Plus" 997.1 S winner tested well above a stock 997.1 S in all-around performance. And when you closely review the numbers for all three, the results are actually incredibly close.
I agree with The Bloke's assessment of Project Z4 M as an involved and satisfying drive-hell, it's my car. The reason for this is the rawness of the chassis feedback through the steering wheel and the seat of the pants. The mildly modified S54 inline six further adds to the driving excitement with improved low-end torque and high-end power, as well as its nasty metallic soundtrack and 8000-rpm rev limit. A major pitfall, however, was its uncertain brake pedal feel, which varied slightly with rpm and reduced driver confidence at the limit. This is by no means an issue with the Brembo brake upgrade; rather, it is the inherent Dynamic Brake Control safety system that includes brake stand-by, brake drying, brake fade compensation, and hill-hold. This factory system does not hold up well when driving at ten-tenths when combined with the Brembos. Interestingly, it behaves normally when driving at nine-tenths or below, and can be overcome with more experience at the limit (i.e., you get used to it).
With a few more tweaks and test sessions, Project Cayman X51 may have won this shootout. Its power, brakes, and handling were up there with the modified 997 S. More experimentation with alignment and tire pressures would have likely further improved this freshly completed project. But you can't win them all. The Cayman was the favorite for speed and driving excitement, providing the driver with a thrilling racecar-like experience. It was interesting to note that the unique handling nuances of the equally powered Cayman X51 and 997 S didn't signal a clear winner. The Cayman's 46:54 front/rear weight bias seemed more stable corner entry to apex, while the 997's 39:61 weight bias was better apex to corner exit. Slow in, fast out has always been the racer's maxim. It seems Porsche has known this all along.
The 997 S reigns supreme. Our test car's bolt-on power mods equaled those of our custom Cayman X51. Chassis additions included only anti-roll bars and lightweight wheels, while a more aggressive track-biased alignment would further improve our winner's handling. It is hard to beat a 911 at the track when it's driven well. Why is it so good? I believe the tail-heavy 911 gains its advantage in being able to get the power down on corner exit. Improved grip is achieved by the combination of additional rear weight, rear-wheel drive, and useful rearward weight transfer. Our test subject 997 S also had a larger rear contact patch with its chubby 305-width tires.
Project Z4M represented itself surprisingly well here, while Project Cayman X51 proved to be an extremely exciting, albeit expensive, track-day warrior. The 911, however, remains the legend, and the benchmark to beat. I have a funny feeling that my next project car will begin on a 911 platform.
The legend-Porsche Carrera 997 S
The 997.1 S is truly a brilliant car, this example coming from the factory ready to go with the cockpit adjustable PASM suspension and carbon ceramic brakes. The vehicle's owner completed some research on his own and put together a very sporting package to bring the car up to his desired performance specifications. GT3s are scarce in his neck of the woods; this is the next best thing.
2008 Porsche 911 Carrera S
Rear engine, rear drive
Weight Bias: 69:61
Curb Weight: 3,250 lb
PCCB Brakes, full leather interior, sport seats, carbon trim
3.8-liter flat six; stock power 355 hp
AWE headers, metallic cats and mufflers, EVO intake with K&N cone filter, GIAC software
395 hp (est.)
H&R sway bars
OEM PCCB assemblies
Champion Motorsport, 9x18, 11x18 (f/r)
Michelin Pilot Sport Cup R-compound, 235/35, 305/30 (f/r)
$80,000 + $10,000 (mods) = $90,000
|TABLE 1: THE BLOKE’S HARD DATA|
|Car||Lap Time||Average Speed||Peak Speed||Max g-Force||Max g-Force||Max g-Force||Time on Brakes|
|*relative measurement, lateral force reading about 20% high.|