Horsepower uber alles

Feb. 17, 2005
Auto designers have no problem catering to our "need for speed."

Horsepower über alles

Not all of the new iron coming from automakers strives for more miles-per-gallon. Some of today's best examples of clever design make the muscle cars of the late 60s and early 70s look like wimps on the beach. The twin mantras guiding these efforts seem to be, "If it has 200 hp this year, let's give the next model 300," and, "Nothing succeeds like excess." No question that some portion of the buying public wants more power. Here's a look at the vehicles that may be zipping past you this year.

World's fastest station wagon

For the family on the go, and in a hurry to get there, Mercedes-Benz is building the E55 AMG wagon. It's a station wagon version of the E55 sedan that has been souped up by AMG, the company's performance group. (AMG stands for the group's two founders, Hans-Werner Aufrecht and Erhard Melcher, and the German town in which Aufrecht was born, Grossaspach.)

It carries a supercharged and intercooled 5.5-liter V8 that pumps out 469 hp and 516 lb-ft of torque at 2,000 to 4,000 rpm.

The 24-valve engine uses a beltdriven Lysholm-type supercharger (or kompressor, in Mercedes parlance). Lysholm superchargers are similar to a helical Roots blower, but the rotors are more twisted and are conically tapered. This makes them more efficient in high-boost situations. They also have higher parasitic losses when they aren't used. The E55's supercharger has aluminum scrolling rotors that generate 11.6 psi of boost pressure. The supercharger also uses the air-to-water crossflow intercooler tucked in the engine's V. It lowers the temperature of intake air, making it denser, further boosting power.

The Mercedes station wagon, like all E-Class vehicles this year, will use electronic braking, making it the first large-scale use of the technology. It lets the brake pedal work with sensors, a computer, an electrically driven pump and high-pressure reservoir, and some ingenious valving. The computer takes inputs, such as speed and ride quality, and controls four fast-acting valves, one per wheel, as they adjust brake pressure.

Although exact pricing has not been set as this was written, odds are it will be somewhat more than the price for the E55 AMG sedan, which goes for $88,220.

Roadster or rocket?

With 604 hp under the hood churning out 738 lb-ft of torque from 2,000 to 4,000 rpm, the two-seat SL65 AMG is the most powerful roadster Mercedes has ever built. The 6.0-liter, 32-valve V12 uses twin turbochargers, but the 4,500-lb car is electronically limited to speeds of 155 mph or less.

The car carries active body control that uses high-pressure hydraulics to adjust the suspension to the driving conditions. The system is said to reduce body roll, dive, and squat. The car also has a retractable hardtop roof. The price for this Teutonic beauty is, hold your breath, a mere $179,720.

An automatic transmission in a sports car? But it's a seven speed.

The SLK55 AMG is the first SLK to be powered by a V8 engine. In this case, it's a 5.5-liter powerplant that produces 355 hp and 376 lb-ft of torque, enough to get it from 0 to 60 mph in 4.9 sec. The modified engine has nearly equal bore and stroke measurements, making it a so-called "square" design. This is considered ideal by many auto engineers because it strikes just the right balance between piston speed, primarily a function of stroke, and valve size, a function of piston diameter.

For smooth, vibration-free performance, each engine is spin balanced, and connecting rods and forged aluminum pistons are installed in weight-matched sets. The engine also uses silicon-aluminum cylinder sleeves to cut back on piston-ring spring tension to improve efficiency. But they aren't pressed into the engine block. Instead, the aluminum block is cast around them. This melts about 20% of each sleeve, bonding them to the block and improving heat dissipation and rigidity.

And although the sports car has an automatic tranny, an anathema to most car enthusiasts, it is a seven speed and comes with Mercedes' version of clutchless, pushbutton shifting. The extra gears give a wider spread between top and bottom gear ratios and mean less rise in engine speed between gears.

Isn't this special?

Porsche has sold 78,000 Boxsters in North America since the car was introduced eight years ago. So for this year, Porsche introduced its second generation of the two-seat roadster, including the Boxster S, which stands for special but could stand for sportier. The S version carries a 3.2-liter, opposed six-cylinder engine that generates 280 hp and 236 lb-ft of torque, and a six-speed manual transmission. It gives the car a top speed of 166 mph.

(The standard Boxster carries a 240-hp, 2.7-liter engine with 199 lb-ft of torque.) The S also has a slightly wider stance than last year's Boxster, more powerful brakes, and the latest vehicle control and handling technologies from Porsche. It also boasts a larger interior to accommodate tall drivers. It retails for about $53,100.

Turbo-ute to the rescue

The Cayenne from Porsche is one of the fastest sport-utes around. But add a bigger engine and twin turbochargers (and tack almost $50,000 onto the price of a straight Cayenne), and you get an even faster and more powerful vehicle, the Cayenne Turbo. This $89,300 SUV gets 450 hp and 460 lb-ft of torque from its 4.5-liter V8. The only transmission available for the all-wheel-drive SUV is Porsche's clutchless Tiptronic system. To keep handling and performance on par with the rest of the Porsche rear-wheel-drive offerings, most torque is sent to the rear wheels. In fact, unless conditions are out of the ordinary, 62% of the torque delivered to the road goes through the rear wheels. Top speed for the Cayenne Turbo is 165 mph.

If all that's too tame, Porsche can send your Cayenne Turbo to Tequipment, its team of engineers who develop racing gear specifically for Porsche. When they're finished, your SUV will have 500 hp and 515 lb-ft of torque. Though your top speed will only be 2 mph higher at 167 mph, the hyperhoppedup SUV will get there more quickly. Zero-to-60 for the Turbo version is 5.2 sec, and for the Tequipment Turbo, it's 4.9 sec. The beefier Turbo also gets upgraded brakes and suspension.

Pony cars for 2005

Mix the Ford 2005 Mustang with Saleen racing technology and you get the S281, a 325-hp four-seater with headturning good looks. The 4.6-liter (281 cu in.) V8 uses three valves per cylinder — two for intake, one for exhaust — to improve engine breathing. For better exhaust, the Mustang carries a variable exhaust system with twin mufflers. Vacuum-actuated valves open above a specified back pressure, sending some exhaust through a second set of tail pipes aimed at the ground.

If you need more power, the supercharged version, the S281 SC, cranks out 400 hp and 420 lb-ft of torque. The supercharger uses a twin-rotor blower capable of pushing 2,300 cc of air into the engine on each revolution and boosting manifold pressure by 7 psi. This lets the blower turn more slowly and at a lower temperature, which lets it get by with a smaller, lighter intercooler. If you still need more power, the S281 E (for extreme) will likely have 500 hp. It will carry a racing version of the S281 V8 that has been supercharged and outfitted with upgraded hardware. And unlike the other S281s, which use a five-speed transmission, the E version has a heavy-duty six speed and a high-performance flywheel/clutch.

Prices seem almost reasonable with the S281 selling for about $39,000, the SC version for $43,000, and the E version for $54,000.

Street legal road machine

With a top speed of 205 mph, the Porsche Carrera GT is one of the fastest production cars on the market. But with a $440,000 price tag, it's the stuff of dreams. The GT's 5.7-liter V10 engine produces 605 hp and 435 lb-ft of torque, enough to take it from 0 to 60 mph in 3.9 sec, if you're quick enough on the pedals and the six-speed transmission. To get the most out of that power, Porsche kept the GT light, using carbon-fiber composites, aluminum, magnesium, and high-strength steel for the suspension and body. Porsche engineers also used ceramics for the brakes and clutch. The brakes rely on ceramic composite discs that weigh half of what their metal counterparts do, yet perform better and last longer. Similarly, the clutch plate made of a carbon-fiber and silicon carbide composite are smaller and more wear resistant. Although luggage space is only 2.2 cu ft, Porsche provides a set of luggage sized for the trunk and finished in leather that matches the seats. If you're interested, better get your order in: The company plans to make just 1,500 GTs this year.

A mid-engine exotic from the U.S.

The Saleen S7, a 750-hp mid-engine supercar, is said to go from 0 to 60 in 2.8 sec and top out a little north of 200 mph. In an amazing display of power and brakes, the S7 can zoom from 0 to 100 mph and then come to a controlled stop in just under 11 sec. The power for that maneuver comes from a 7-liter V8 with dual turbochargers that puts out 700 lb-ft of torque. The aluminum engine block carries titanium vale retainers, beryllium exhaust valve seats, and an aluminum throttle body. The ball-bearing turbos add 5.5 psi to intake air and dual electric feed pumps feed fuel into the engine at up to 52 lb/hr. The 41-in.-tall car weighs about 3,000 lb and carries a $555,000 price tag. And for those long trips, trunks in front and back provide 5.47 cu ft of space, and the car comes with a threepiece set of luggage designed to fit.

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