'08 Corvette, Current Daily Driver
The Porsche was listed on eBay,
Rennlist, and 6speedonline, so it was only a matter of time before the next owner was overwhelmed by its good looks. With
that in mind, I started shopping for a 2008 Corvette. Many friends thought I should pick the 505hp Z06 model, which was
performing exceptionally well on both the drag strip and the road race track. But the Z06 commanded about a $25,000
premium, and all I could think about is what I could do with a base Corvette and $25k worth of modifications. Besides, where's
the fun in buying a car and then just driving it. I like to make things, or at least modify things such that they are more to my
liking. The base Corvette model gave me more room to play.
Along with a new steering rack design purported to provide
more feel (see Porsche page for my C5 complaint) Chevrolet added two significant new options for the '08 model year; a new interior
upgrade incorporating leather for the dash and door panels, and the "dual mode" exhaust. In the olden days we
called this exhaust feature "cutouts", which brought to mind the type of street racing teenage hoodlum sanitized by the
movie American Graffiti, so that term will not do in these politically correct days. But it works the same! There are two
selectable exhaust paths, one conventionally muffled and the other bypassing the muffler. The sound difference is significant!
The only other option I specified
was the new-for-2008 Jet Stream Blue exterior color. Very attractive in person, it is difficult to photograph because the color
varies quite a bit with your viewing angle as well as the angle of the sun. Bright camera flashes cause a bright green glow at the
points of reflection that the naked eye never sees. The effect is captured below despite all my efforts to avoid it.
My new project joined the as-yet unsold Porsche in February of '08.
Driving these cars back-to-back underscores how completely different too similar-sized sports cars can be. The Porsche feels nimble,
eager to change direction, with abundant feedback through the steering wheel. The Corvette, despite being hundreds of pounds
lighter, feels numb and ponderous by comparison. But oh, the Torque!!! Corvette clutch take-up is precise, and the shifter
is smooth and solid. And on my favorite test pavement, the two cars post nearly identical speeds. It boils down to what
moves you as a driver. If you like the Vette, the 911 feels anemic and twitchy. If you like the Porsche, the C6 feels like
piloting a powerful warship. I kept the Vette!
The Z06 model addresses five main
design factors; more power, bigger brakes, different suspension components, wider bodywork to cover much bigger tires, and substitution
of light weight materials to minimize the overall car weight. I planned to address those five factors in my own way, and at less cost
than the $25,000 premium Chevy charges for the Z06. One Z06 component I was not interested in duplicating was the aluminum
frame rails, which have two drawbacks. One, so far nobody has worked out a way to weld a steel roll bar to an aluminum frame.
Roll bars are both desirable and mandatory for some classes when running a car on the race track.
Second, a Pratt and Miller program manager explained to me how
they tested a base coupe, convertible, and Z06 for torsional stiffness. To understand this, picture clamping the front and back of the
car in two separate, giant vices. Then, hold one of the vices still while twisting the car by rotating the other vice. What
P&M found is that the Z06 model was the most flexible of the three, while the base coupe was the stiffest. Apparently, the
structural supports Chevy added to the Z06 did not compensate for the fact that aluminum is more flexible than steel. Torsional
stiffness results in better behavior on the race track.
OK, so I have my base coupe, and it's
time to nudge it up to, and beyond, the Z06 performance envelope. If you have read my other car pages, you can guess what I did
first. After reviewing all the data I could find about supercharger systems, I selected a Vortech "t-trim" kit designed and
sold by A&A Corvette. This kit is well engineered and complete, and the t-trim blower has a CARB EO number, which is essential
for parts used on public roads in California. Also shown in the picture below is the thick DeWItts radiator I installed in place of the much
thinner factory unit. It gets hot at Thunderhill in summer, 90s and 100s, so this engine cooling improvement should circumvent
overheating problems at the track.
The picture below right reveals the intercooler peeking through the new grille. This
picture also reveals that I've now covered the second Z06 factor - wider bodywork. I ordered the full set of Z08 body conversion parts
from Gene Culley, founder of GM Parts House. Gene put together a
kit with every panel, seal, screw, and trim needed to convert a base coupe to Z06 body panels. I looked to favorite body-man Ryan at
RJ's Paint Shop in Pleasanton. I've used RJ's for al my paint work, stating with
the new hood I needed after adding the supercharger to my previous Corvette. RJ does excellent work at a very fair price.
The significantly wider fenders with the original
relatively narrow tires resulted in a clown car look. I really liked the 10-spoke wheels I had on the 911, so I hunted down a set of 10-spoke
Forgeline wheels, 19" x 13" in the back and 18" x 10.5" in front. There aren't many tire options in the sizes I needed,
but my previous experience with Michelin PS2s made them an easy choice.
With the power and wide
wheels/tires/bodywork covered, it's time to massage the brakes and suspension. The base model handled amazingly well straight
from the factory, but my experience suggested that there was room for improvement, especially in the area of race track capable braking
performance. I enjoy experimenting to gain knowledge, so my first choice was a set of adjustable shocks. Callaway/Eibach
coilovers looked like the best balance between adjustability and affordability. Other setups at the same or lower price point offered more
limited adjustment capability, or none at all. The Eibach shocks provide independent adjustment for compression and rebound, each
with 10 steps. The coil springs (which fit over the shocks, hence the name "coilover") are easily changed to stiffen or soften
the suspension as desired.
I turned to StopTech for upgraded brakes.
The front calipers are fitted with 6 pistons each, while the rears, having less work to do, provide 4 pistons per caliper. Fourteen
inch slotted rotors are fitted on all four corners. The most recent modification was to replace the factory antiroll bars with adjustable bars
from Pfadt. At this point I figured the car was ready to roll.
Sometimes aftermarket parts can bite you.
Thinking back over all my years in the hobby, it seems as though I've been bitten a lot! I commuted 65 miles per day in the car
as shown in the pictures above. The rear suspension developed a groan that I could not pinpoint. It was not an alarming sound,
just annoyingly persistent. One day, as I got near home on my evening commute, I heard (and felt) a loud bang from the rear of the car.
I immediately pulled over to investigate. There were no mangled parts dragging on the ground and no dripping fluids. In
fact, everything appeared to be normal, so I finished the ride home.
Removing the right rear wheel revealed
the damage - the shock absorber broke into two pieces. Fortunately, the remaining stubs retained the coil spring such that the car did
not drop down onto the tire. That would have been expen$ive! Eibach warranteed the broken part, but I decided not to tempt
fate again. The coilovers were sold and I'm currently running the original shocks and springs. I'm not sure what's next, but plain
old nonadjustable, but very reliable, Bilsteins are looking pretty attractive.
Other than the numb steering and a somewhat lifeless feel
compared to the 911, I'm really enjoying this car. It is plenty quick enough for a daily driver. I have seen 1.25g on banked
freeway on-ramps, and the brakes are phenomenal. So what's next? Well, I mentioned that there are two cars on my 'want to own
someday" list, one of them being the Porsche. The other, along with being a very capable sports car, is capable of making
sounds that are music to a gearhead's ears.
Click here for a hint. (Note: 2.5 MB Windows Media video)