Chevrolet Corvette

Before the arrival of Dodge Viper, Corvette used to be the dream of every American car lovers. The first Corvette appeared in 1955. In then it was powered by an underpowered inline six cylinder engine. The second generation, nickname "Sting Ray", appeared in 1963. High output "big block" V8, a much improved chassis and an aggressive styling brought it true success and reputation as the best sports car in the USA. In mid-70's we saw the third genration hit by oil crisis and lost a hundred horsepowers. Other areas did not improved much from the Sting Ray too. The forth generation in 1984 received a fuel-injected small block capable of 230hp, a much modernised appearance and chassis, all double wishbones suspensions, also the advanced ABS. Near the end of its life, C4's pushrod V8 was upgraded to the 300hp LT1, and at last the 330hp LT4, but the basic design was never changed.  

Nearly all Corvette used to be praised of powerful engine and electric performance, but at the same time was criticised as lack of handling goodness and ride comfort. As time went by, American get used to these characters and decribed them as "American spirit". They didn't care a Porsche 944S outhandle their dream car, just emphasis the time measured by the stop watch.  

The situation has changed, if not revoluted, since the arrival of the C5. Like the classic Sting Ray, the C5 was developed started from a clean sheet. GM's engineers went to the drawing board to create a completely new chassis, which is claimed to be 4.5 times stiffer than the poor C4. It's a back bone chassis, inside the transmission tunel there is a 5-in diameter torque tube rigidly connected between the engine and the rear-mounted transaxle. Chassis rails are made by hydroform process, a technique using liquid pressure to shape a metal tube with the advantage of uniform thickness in everywhere, thus improve rigidity / weight ratio.  

The stiffer chassis allows the suspensions setting to be softened, thus enhance ride comfort yet still make the car handles more stable than its predecessor. By using aluminium suspension arms, unsprung weight is vastly reduced thus once again improve ride quality. It also helps to cut weight.  

When talking about weight saving, the all-new LS1 engine must be mentioned. Strangely, GM still develop a new pushrod engine in the late 90's, and even use it to power its flagship sports car. Some people said the development cost of a new pushrod V8 is just a fraction of a new high-output multi-valve dohc V8, while Cadillac's Northstar is not supposed to be able to tune to about 350hp and 350lbft. Another opinion said a 5.7 litres pushrod V8 can maintain the torque-biased characteristic that Corvette lovers used to admire.  

The LS1 engine features aluminium head and block, the latter a first for Corvette and itself alone saves 40 kg. Lighter engine also improved weight distribution to 51 : 49 between front and rear, nearly perfect !  

The new V8 displaced 5665c.c., just dozens c.c. less than its predecessor. In-plane pushrod valve gear reduce friction and make it more compact. Electronic throttle enables a more effective traction control to be equipped, and even the optional "Active Handling Chassis Control System", a kind of electronic stability control. An easier visible new feature is a thermoplastic intake manifold, which saves weight.  

Weight saving also extend to the roof, which has a magnessium frame. Overall speaking, the C5 is 36kg lighter, yet the chassis is a lot stiffer, yet its width and wheelbase exceeds C4 by 25mm and 210mm repectively in order to improve handling.  

Looking from outside, the C5 is just an evolution from C4. It doesn't imply the revolution under the cost-saving composite body, but it also preserves the shape that many Corvette lovers want. One thing they may not notice is, the coefficient of drag is now lowered to a remarkable 0.29.  

Open the door, you'll find the door sill is lower. The seat might not be very supportive for such a fast car, but there is generous of foot room compare with TVR, thanks to the rear-mounted gearbox. Fire the engine and start going, the V8 has mountain of torque to soar your neck. Its noise is not in Ferrari's or Porsche's quality, probably because of the lack of rpm. Very fast, the C5 push all the way without sweat, reaching 60mph in 5.3sec, passing the ton at 11.5sec. It tops slightly above 170mph.  

Undoubtedly, handling and ride has been improved very much. In the past, every European car magazine criticised the C4 in this aspect without mercy, now their words become much more careful. "Reasonably good" seems to be the best phrase to describe the C5's handling and ride, as it is still not up to the level of the European bests, say, Porsche Boxster, Lotus Esprit and TVR Cerbera Speed Six.  

I personally like to mention the Cerbera Speed Six as its opponent. Similarly powerful, similarly priced and similar composite body make them logical rivals, just separated by the Atlantic ocean. Facing the TVR, Corvette's steering seems quite lack of the final feeling. It corners without the adjustability and compliance as the Cerbera, goes in straight line slower than the British lightweight too. Speed Six takes just 4.5sec and 10.2sec to 60mph and 100mph respectively, even faster than the electric Corvette. Its 24 valves straight six is high-revving yet smooth, deliver excitement that the torque-biased pushrod V8 cannot hope for.  

However, the Corvette is still the best choice in its price range for most people. It has the advanced equipments (ABS, Traction control, Stability control) and luxury items that the raw TVR never offer. It is an everyday car suitable to go to work, to the beach and also to have an exciting weekend drive. Moreover, Corvette is available in convertible version too. 

The above report was last updated on 18 Feb 99. All Rights Reserved.

Corvette Hardtop

Replace Corvette's removable roof with a fixed, glass-fiber roof incorporating a smaller rear window, delete the standard adjustable damping, the power seats, the power steering wheel etc. save the Corvette Hardtop 36 kg of weight. Besides, the chassis becomes stiffer. This makes the Hardtop to be fractionally faster accelerated ( Car & Driver reported 0.1 sec reduction to 60mph ) and has more sensitive steering feel. Of course, the standard sports suspension setup also plays an important role. 

In terms of top speed, the hardtop is actually slower, since the new roof replaces the smoothly sloping big rear windows with a tiny, suddenly dropping one. This deteriorates the drag slightly, thus reflects in top speed. 

Just like other stripped-out Porsche and Lotus, the Corvette Hardtop is cheaper than the normal version. 

The above report was last updated in 1998. All Rights Reserved.

Corvette Z06

Z06, what a cool name. Chevrolet Corvette used this name for the first time in 1963, representing a hotter, race-ready Sting Ray. Today, the Corvette Z06 is reborn in a more user-friendly form, not as racy as Mustang Cobra R but it is easily the hottest Corvette since the ZR1. Compare with the standard Corvette, it gets 35 extra horsepower yet weighs less, further with improved suspensions, tyres etc. to complete an exciting package.  

Z06 isn’t a response to Cobra R or Viper GTS. The former is too race-track bias and has to sacrifice a lot of comfort and style as a result. The Viper remains to be the King of American sports cars, but it is too expensive for most car lovers. In contrast, Corvette Z06 retains most of the good elements of the standard Corvette, such as comfort and keen price, offering it a clear advantage in sales number. 

However, horsepower and torque still matter most to the American, so do 0-60 and quarter mile time. While the Corvette has no hope to match the 8-litre V10-powered Viper, it must beat the Mustang Cobra R, which costs 10% more than the Vette. Thankfully, the LS1 all-alloy V8 is relatively new and has a lot of potential for development (its specific output is just 61 hp per litre, you know, Callaway has already improved that to 78 hp / litre or a total of 440 horsepower). Therefore it doesn’t need a magic to get extra punch. What it needs are higher flow intake manifolds, new cam profiles with faster timing and higher lift, increase of compression ratio from 10.0:1 to 10.5:1 and improved air flow inside the block to reduce piston back-pressure. These modifications raise the red line from 6,200 to 6,600 rpm, enhance peak power and torque to 385 hp / 6,000 rpm and 385 lbft / 4,800 rpm respectively. For your information, the standard Corvette has also been improved to 350 hp and 375 lbft recently, thanks to a similar intake manifold and revised timing to camshaft. 

Compare with Cobra R, Z06’s engine - now calls LS6 - has exactly the same peak power and torque, although the longer stroke of Cobra R enables more bottom-end torque. However, the LS6’s aluminium block has decisive weight advantage over the Cobra R’s cast-iron one. That translate to a front-to-rear weight distribution of 53:47 against 56.5:43.5. 

Being the hottest Corvette, the Z06 is only available in the form of Hardtop, which is slightly lighter yet stiffer than the Targa. Even so, an extra 16 kg has been ditched from the standard Hardtop, thanks to thinner windscreen, lighter tyres and an exhaust made largely of Titanium (the first road car using this).  

Despite of more power and less weight, Chevy still revised the gear ratios of the Getrag 6-speeder to enhance acceleration. Chevrolet’s official press release said the car is capable to reach 60 mph in 4 seconds flat, but their figures are usually too optimistic. Motor Trend timed 4.53 seconds, which is nearly half a second quicker than the standard Corvette they timed. Launch in a normal grip road, I believe 4.6 seconds is more realistic. 0-100 mph just marginally fails to qualify for the "Sub-10-sec Club". 

Suspensions have received thicker anti-roll bars, stiffer springs, plus revised camber settings. The tyres grow in size - the front from 245/45ZR17 to 265/40ZR17, the rear from 275/40ZR18 to 295/35ZR18, all are Goodyear’s new Eagle F1 SC, with improved pattern, stiffer side wall and reduced weight. Brakes haven't changed, but an odd-looking air intake is added to just in front of each rear wheel, which enhance rear brake cooling by 10%. 

You might expect the car to be electric fast, but bearing in mind that the standard Corvette is ALREADY very quick, and the Z06 is just 10% more powerful and 2.6% more torquey, it doesn't feel too much more punchy than the standard car. In fact, if not push the LS6 to high rev, it won't deliver more torque than the LS1, although the noise generated is always more sporty at any rev, thanks to the new exhaust and intake manifolds.  

Handling, on the other hand, has been improved. Body control is just rock steady, balance and poise is superb, although ride quality suffers a little bit on uneven surfaces. Steering is very neutral. Strong grip from the new tyres raises cornering limit to new height - how many supercars can manage 1g lateral acceleration? It can be driven incredibably hard. At the safety side, the second generation Active Handling Chassis Control System (GM's version of ESP stability control, developed by subsidiary Delphi) acts as the safety net without ruining driving pleasure. Its new software has improved the smoothness of intervention to the extent that many drivers can hardly notice. Of course, maximum lap time must be recorded with the electronic control switched off. 

Any flaws ? yes, as usual, the Corvette doesn't has a steering feel to match Viper or any Porsche. The 6-speed gearbox doesn't shift as good too. It requires effort and decisive actions. That's all. 

The Z06 Corvette pushes performance envelop to new level with minimal trade-off in comfort. It is far more easier to drive than Viper and Cobra R. In terms of agility and control, Porsche Boxster S is still the master, but the Z06 will leave it bite the dust. So, is Z06 the last word of affordable sports cars ? not yet. Skyline GT-R is nearly as quick while handles better, feels sharper, agile and have all controls setting up precisely. Z06 might be the best from the USA, but not world-beating yet. 

The above report was last updated on 8 July 2000. All Rights Reserved.

405hp Z06

The best American sports car gets better. With 20hp and 15lbft added, now it qualifies the "400-horsepower Club". Perhaps a membership of "10-seconds Club" (for 0-100mph) is also possible. For your information, the old Corvette Z06 did that in 10.5 seconds according to the test of Road & Track. 

Now I won't underestimate the GM small-block V8 anymore. This push-rod engine is awesome, generating the maximum power of 405hp at 6,000rpm and 400lbft at 4800rpm. That is in the same territory as Aston Martin's 6-litre V12. Its specific output raised to 71.5 horsepower per litre, probably a record for normally aspirated push-rodder. Among those 20 additional horsepower, about 10 comes from improved airflow to and out of the engine. This include a smoother air filter box and the deletion of precatalysts (improved underfloor catalysts can handle that). Another 10hp comes from increasing valve lift and by using lightweight hollow, sodium-filled valve stems. As you can see, these modifications benefit high rev breathing, so most of the extra punch arrives from 5,000rpm up. 

Suspensions also received continuing development, but the tweaks are too minor to be mentioned. 

The above report was last updated on 17 Sep 2001. All Rights Reserved.


Corvette 50 Anv
Corvette Z06
Front-engined, Rwd.
Front-engined, Rwd.
Front-engined, Rwd.
L / W / H / WB (mm)
4565 / 1869 / 1212 / 2655
4565 / 1869 / 1212 / 2655
4565 / 1869 / 1212 / 2655
V8, ohv, 2v/cyl.
V8, ohv, 2v/cyl.
V8, ohv, 2v/cyl.
5665 cc
5665 cc
5665 cc
345 hp
350 hp
405 hp
350 lbft
375 lbft
400 lbft
Suspension (F/R)
All: double-wishbone
All: double-wishbone
All: double-wishbone
Tyres (F/R)
245/45 ZR17 / 275/40 ZR18
245/45 ZR17 / 275/40 ZR18
265/40 ZR17 / 295/35 ZR18
1480 kg
1465 kg
1414 kg
Top speed
171 mph (c)
173 mph (est)
180 mph (est)
0-60 mph
5.3 sec*
4.9 sec*
4.5 sec*
0-100 mph
11.5 sec*
9.9 sec*

Figures tested by: * R&T

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