No Roof, No Problem: 1,105 HP C6 Corvette Grand Sport Goes Topless

For some of us, going topless doesn’t mean being asked politely to put our shirt back on. Some of us, but not all of us, prefer to refer to “going topless” as a reason to pop the top on a car like this Corvette C6 and hit the next race track, highway, or a hellacious hill climb. It’s the ultimate excuse to let the cool night breeze flow through our hair or whatever stray strands are still left up there, that this.

C6 Convertible

One Hot Corvette Summer

Bought in 2018 from the Corvette Warehouse, Bill’s desire to own a C6 stemmed straight from necessity. The guy already owns a C3, C5, and a C8. So what’s one more little Vette in the shed, right?

But for Bill, it’s more than just collecting Corvettes. It’s about connecting, and reconnecting with his roots. From the moment he encountered the film Corvette Summer when he was a boy, Bill’s infatuation with the venerable vehicle evolved into the extreme.

Now, as for how Bill got into racing, let’s say that would require its own separate article. Just know that racing a ’68 Camaro against anything encountered on the asphalt was a staple for much of his youth. And when the whole family and career portion of his life finally set in, finances and free time shifted gears away from project cars semi-permanently. Note the “semi” portion of that last line, people. It’s pretty important.

A C6 Reborn to Race

By the time this 2010 Chevy Corvette Grand Sport ended up in Bill’s driveway, he had already gotten to a point where he could afford to dive headfirst back into modding and racing GM machines. And so he did, knowing full well that things could go sideways at any moment.

As far as Bill was concerned, this convertible Grand Sport was never meant to rock a stock LS3. It was never meant to have a head & cam combo with a supercharger running on E85, either. Yet build it, he did. A first attempt that yielded an impressive 819 horsepower at the wheels and a huge smirk on its owner’s face.

But Bill and his team at 820 Performance of Fort Worth, Texas, knew they were working on borrowed time. The stock block and heads on the LS3 were never intended to withstand that level of abuse. At least not routinely. This is precisely what happened when the original LS3 lifted a head, thus torching the entire block.

But a magical thing happens whenever someone pushes a machine (or its engine) to the limits. Even with the utter destruction of the entire powerplant dangling in the balance, plans for a better build begin to foster a fresh future.

Some consider it the “Phoenix Cycle” for automotive enthusiasts and race car teams. This is how the C6 got the internals and tuning it needed. Control, on the other hand… let’s say that’s still on the “must add” list.

C6 Convertible

Built Today, Gone Tomorrow

The biggest obstacle to the current build has been power management. Bill’s C6 has so much low-end torque that it blows tires off in every direction imaginable. Despite switching to a MoTeC ECU, followed by some intense recalibration tuning sessions, things are still a bit dicey even today. The toggling of traction control during launches may help, but even that struggles to hold this bounder back.

Curious about how this stage of the build has been progressing as of late, we inquired about this tricky traction control system. Bill tells us that he is currently leaving at 60-percent throttle before bringing full power back in. A risky move when leaving the line, but lightning strikes when that grippy Mickey Thompson race rubber hooks up.

This car is built to be a contender in the True Street Class and possibly Small Tire Class… but still driven on the street, to car shows or even drag events… – Bill Parker.

C6 Convertible

We’re not exaggerating when we say this C6 convertible is quick. Currently, Bill runs in Daily and Outlaw Daily race classes. A single dry shot from Nitrous Express delivers the additional oxygen his C6’s heavily reinforced LME LSR motor craves.

With 986 lb-ft of torque at the ready and 1,105 horsepower at the wheels, this Vette’s best eighth-mile ET stands at 5.40 seconds at 127 mph. At the same time, Bill’s best 60-foot time sits squarely at 1.35 seconds. And remember, that’s with him dialing everything back on the torque end.

C6 Convertible

Looking Back, But Focused Forward

With 47,398 miles on the odometer, and a 2-year build still being budgeted out, Bill Parker’s 2010 Chevy Corvette Grand Sport is more of a handful than ever. Despite all that, it remains the 54-year-old’s hope to get this C6 to a point where it can run in True Street and even Small Tire classes. 

Finally, it is worth noting that this convertible Corvette is still completely street-legal. Bill is eager to point out that his C6 still has a full interior, working AC, and a banging stereo system to boot, complete with a 12-inch subwoofer and booming bass. These are all very uncommon items to find in a vehicle racing in classes where gutted race cars are the norm. Maybe taking that top off did help a bit after all…

Build Details


Make/year: 2020 LSR Block

Current cid: 400

Bore/Stroke: 4.125 in. x 3.625 in.

Crankshaft: Callies Compstar 8 Counterweight

Pistons: Diamond

Connecting rods: Callies Ultra Billet H Beam

Compression ratio: 10.0:1

Engine built by: Late Model Engines of Houston, Texas

Camshaft make: Custom grind from Cam Motion

Cylinder heads make/type: Frankenstein M311



Engine tuner: Modified By KC

Injector size: 1700cc

Pump(s): Fore Triple Pump

Intake manifold: Holley

Throttle body make/size: Katech 103 mm

Headers: Kooks

H/Xpipe: Kooks

Mufflers: Factory Z06

Pipe size: 3 inch


Nitrous Oxide System: Nitrous Express

Wet or Dry: Dry

Jet size(s): 54

Supercharger System: Vortech Superchargers

Headunit Model: A&A YSi

Intercooler: Custom air to water


Type: RPM Power Glide

Clutch / Converter: Freak Show

Shifter: B&M

Stall speed: 3,800 rpm


Type: Ford 9-inch

Gears: 3.50:1

Axles: G Speed

Differential: Spool


Front upper/lower control arms: Stock

Front shocks/struts: Mencer Coilover

Front sway bar: None

Steering box: Power 

Rear upper/lower control arms: Stock

Rear shocks: Mencer Coilovers

Rear springs: Mencer

Rear sway bar: PFADT


Front: Weld S77 17 x 6-inch Custom candy copper powder coat

Rear: Weld S77 15 x10-inch Custom candy copper powder coat

Tires, front:  Mickey Thompson front runner radial 26x6x17

Tires, rear (street/strip): Mickey Thompson pro radial 275/60-15


Front: Aerospace Components

Rear: Carlyle Racing


Color: Arctic white

What condition was it in when you bought it? Very good

Body modifications: Simpson parachute mount for a 4,000-lb rated ‘chute

Hood: Factory Grand Sport w/ Track Spec hood vents

Spoiler: Carbon Fiber flush mount


Roll bar/cage: RPM 6-point cage, custom powder coated in candy copper to match the wheels

Other safety equipment: 5-point harness

Other interior mods: Corbeau Seats, parking brake handle delete for MotionRraceework parachute handle

Gauges: Custom switch panel for the MoTeC


Best 1/8-mile ET: 5.40 seconds

MPH: 127

60ft. time: 1.35 seconds

Horsepower: 1,105 rwhp

Torque: 986 lb-ft

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About the author

Micah Wright

Raised on LEGOs by grandfathers who insisted on fixing everything themselves, Micah has been a petrolhead in training since age four. His favorite past times include craft beer, strong cigars, fast cars, and culinary creativity in all of its forms.
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