turbocharged & intercooled
hp per liter
seconds @ 98.5 mph
(from General Motors
Press Release) With the SS moniker on its front doors and
liftgate, GM Performance Division (GMPD) engineers made sure the ’08
Chevrolet HHR SS lived up to the heritage of those badges. The HHR
SS is not the first production SS model developed by GMPD, with such
standouts as the TrailBlazer SS and Cobalt SS Supercharged under its
belt, but it is certainly the most important since the group is now
responsible for the “go, stop and turn” credibility of all future SS
The HHR SS is powered by a turbocharged and intercooled 2.0-liter
Ecotec DI engine that delivers 260 horsepower (194 kW) and 260
lb.-ft. of torque (353 Nm) with the standard five-speed manual
transmission. It is rated at 235 horsepower (175 kW) with the
available automatic transmission.
Features such as “no-lift shift” and other driver-selectable
performance modes help the HHR SS achieve 0-60 mph performance in
6.3 seconds and cover the quarter-mile in 14.8 seconds at 98.5 mph.
The top speed is more than 150 mph, with the manual transmission.
“The HHR SS offers drivers a totally integrated performance driving
experience,” said John Heinricy, GM Performance Division executive.
“It was developed on some of the most challenging tracks in North
America and Europe, and has been tuned to deliver confident handling
and road manners, while also maintaining overall ride comfort.”
As with other GM Performance Division-developed vehicles, the HHR SS
was validated on Germany’s famed Nürburgring racing circuit, where
it set a new lap record of 8:43.52 minutes for its class, besting
the previous record of 8:54.38 held by the Opel Zafira OPC.
“It’s not often that you see a vehicle like the HHR at Nürburgring –
and you certainly don’t see one lapping the track as quickly,” said
Heinricy. “Frankly, the HHR SS is going to surprise a lot of
enthusiasts with its improved control and feel on both the street
and the track.”
2.0L Ecotec DI turbo engine
The Ecotec 2.0-liter
turbo engine produces 2.1 horsepower per cubic inch of displacement
(130 hp / 97 kW per liter) and is the most powerful engine in the
Ecotec family. Gasoline direct-injection technology helps the Ecotec
engine produce more power while maintaining the lower fuel
consumption of a small displacement port-injected engine.
With direct injection, fuel is delivered directly to the combustion
chamber to create a more complete burn of the air/fuel mixture. Less
fuel is required to produce the equivalent horsepower, especially at
normal cruising speeds, of a conventional port-injection combustion
system. Direct-injection technology works well with turbocharging
and helps deliver a great balance of power and economy.
Highlights of the HHR SS’s Ecotec 2.0L DI turbo engine include:
head with stainless steel intake valves and sodium-filled
engine-driven fuel pump
Mobil 1 synthetic
the steel crankshaft and forged connecting rods are
high-strength items that provide strength and enhance
durability. Oil-spray piston cooling helps reduce cylinder
temperatures and promotes longevity by delivering pressurized
oil that continuously lubricates the pistons, which reduces
friction. To enhance combustion, the piston tops feature a dish
shape that deflects incoming fuel toward the spark plugs.
To accommodate the
direct-injection system, the Ecotec 2.0L DI turbo has a unique
cylinder head and intake manifold. The cylinder head incorporates
mounting locations for the fuel injectors – items that are typically
mounted in the intake manifold on port-injection engines.
Specialized and extremely precise multi-hole fuel injectors are used
to meter fuel and deliver it in a finely atomized manner. They are
supported by an engine-mounted high-pressure fuel pump.
Apart from the mounting positions of the fuel injectors, the
cylinder head has conventional port and combustion chamber designs.
Large stainless steel intake valves and sodium-filled exhaust valves
are durable components designed to stand up to the high-performance
capability of the engine.
The unique cylinder head, fuel system, pistons and intake manifold
are the major components that differentiate the 2.0L DI turbo from
other members of the Ecotec engine family. Mobil 1 synthetic engine
oil is installed at the factory. Synthetic oil was selected for its
friction-reducing capabilities and high-temperature performance.
Turbocharger and charge air cooler
Pumping up the HHR SS’s
2.0L Ecotec engine is an intercooled turbocharger system. The turbo
blows pressurized air into the combustion chambers to enhance
horsepower and torque, while the system’s intercooler circuit cools
the turbocharged air charge to maximize its effect. The turbocharger
is sized to deliver a significant horsepower boost and almost no
spool-up lag. Maximum pressure is almost 20 psi.
Because the pressurized air pushed by a turbocharger becomes heated,
the HHR SS’s system employs an air-to-air intercooling system. With
it, the pressurized air passes through a heat exchanger mounted
behind the grille in the lower front fascia, where it is cooled
before it enters the engine. Cooler air is denser, enabling the
combustion chambers to draw in more air for maximum power. The
cooler air also staves off the possibility of detonation at higher
temperature, which allowed engineers to tune the engine for maximum
power and ensure consistent performance in all driving conditions.
Backing the turbocharged
engine is a standard GM Powertrain Sweden F35 five-speed manual
transmission; the optional automatic is GM Powertrain’s 4T45
electronically controlled four-speed. Semi-synthetic transmission
fluid is used for its capability of absorbing heat and resisting
breakdown during high-performance driving.
A performance-oriented feature referred to as “no-lift shift” allows
maximum performance with the manual transmission – upshifts can be
performed very quickly without lifting the throttle. An algorithm in
the engine’s controller enables this high-performance feature, which
helps maximize acceleration and gear changes.
A short-throw shifter with stiffened shifter bushings and modified
cables and attachments enhances confidence behind the wheel, giving
the driver a firmer, more direct and quicker shift feel. The manual
shifter also is located higher than other HHR models, placing it in
a more intuitive position for performance driving. An SS-specific
center console is wrapped around the short-throw shifter.
A limited-slip differential is available with the manual
Chassis tuning and brakes
Conveying the HHR SS’s
turbocharged horsepower to the pavement is an FE5 sport suspension
that includes a host of other chassis, steering and braking
revisions – and a set of gorgeous 18-inch forged aluminum wheels.
The elements pull together to give the vehicle surprisingly agile
ride and handling characteristics, as well as an enviable maximum
lateral acceleration rate of 0.86 g (with the manual transmission) –
grip comparable to many sports cars on the market.
The MacPherson strut independent front suspension uses SS-specific
gas-charged twin-tube struts, unique steering knuckles with
optimized geometry, 28 N/mm linear coil springs with specific damper
tuning, stiffer control arm handling and stabilizer bar bushings,
and a direct-acting, 23-mm solid stabilizer bar. At the rear, the
SS’s semi-trailing twist beam axle uses monotube gas-charged shocks
with specific damper tuning, a 24-mm solid stabilizer bar, stiffer
axle bushings and multi-rate coil springs (30-40 N/mm). StabiliTrak
electronic stability control and traction control are standard.
A unique electric power steering (EPS) system is tuned to match the
SS’s handling prowess. The rack-and-pinion gear has a quick 14.8:1
ratio, which is 20 percent quicker than other HHR models, and the
new EPS provides improved precision and a more viscous feel. A
smaller-diameter steering wheel enhances the quick, sporty steering
Four-wheel disc brakes with ABS are standard. They consist of
11.65-inch-diameter (296 mm) front vented rotors with 54-mm
single-piston calipers in the front and 9.84-inch-diameter (270 mm)
rear solid discs with 38-mm single-piston calipers. The standard
anti-lock brakes are connected to the StabiliTrak electronic
stability control system to enhance stopping and handling in
emergency driving situations.
The disc brakes are visible behind one of the HHR SS’s most
distinguishing features: a set of 18-inch polished forged aluminum
wheels. The wheels have a Corvette-inspired split-spoke design and
ride on SS-specific Michelin Pilot Sport performance tires that are
rated for all-season driving.