Editor's note: We've received fact-rich VETTE File submissions before, but Don Harr's write-up on his "Sharkee" '82 C3 lent new meaning to the term "comprehensive." Perhaps that shouldn't come as a surprise, considering that the San Jose, California, resident is both an avid racer and an engineering guru who specializes in performance-exhaust tuning. We'll let Harr take it from here.
When I first built Sharkee's body, I simply cut out the fenders and glued in Eckler's louvers. That was easy. But then I decided that the hood also needed louvers to provide a balanced style, especially with that long front end. I visited the local Chrysler dealer and told the guy in the parts department I wanted a couple of Viper louvers. We had to cut off the curved parts, then glue the remaining flat parts together. I also trimmed two louvers from each, leaving four instead of six.
My fiberglass man told me he could not insert them, though, because they were plastic and would warp in the California sun (due to the difference in shrinkage rates between plastic and fiberglass). So he made a mold off of the louvers to produce another set. That went on and on till the fourth set finally worked. The long-nose look was also enhanced by using a hood-extension piece (taken from a '75 Corvette hood) up near the windshield.
The flares were custom made off of the '82 fenders by cutting the fender lips off the car and remounting them exactly 2 inches farther outboard. We then reformed the open area with new fiberglass. This way, the flats on the fender edges were retained in full '82 style. All the flares can accommodate 11-inch-wide wheels with 315s on them, or big 15x10s with 325s in the back.
The steering knuckles were also ground down, the parking brake cables were rerouted on the trailing arms, the fiberglass spring ends were trimmed, and the lower rocker panel's forward end was trimmed down, too. The backspacing on the 17s is 5 inches, and they fit fine. Note that this keeps the offset normal, and the bearings don't get abused.
For me, it's better to be different. I think Bogart wheels have the right style for a competition car. This design, called the LS6, is a six-spoke racing wheel that weighs around 16 pounds. The three-piece construction allows for precise backspacing to work within the tight constraints Sharkee's wheelwells. I really packed them in, too. There's about 1/8 inch clearance to the edge of the rim.
Viewing the Dana 44 differential, which came stock on the '82 Corvette, you can see the additional welded bosses where the adjustable threaded rods are. On the inside are two "feet" on the ends that press up against the aluminum caps that hold the gears in place. With this additional support, the caps aren't torn away upon launching the car.
This mill was envisioned as a small-block version of the pinnacle of traditional Chevy power: the 454ci LS7. What I intended to do was capture the LS7's internal specs in my SBC. I measured the head-port lengths of both the big- and small-block heads, then evaluated the chamber sizes with reference to the length of the ports. I found I could "copy" the oval-port size into my small-block heads by using Brodix Trac 1X raised-runner 230cc ports.
The goal was high-velocity street-type heads for 2,000- to 6,000-rpm use. In the small-block, 230cc ports at 5.2 inches length (BBCs are 6 inches) and a Super Victor manifold proved to be just the right size for a 454 running in the midrange rpm zone. After flowing the heads (318 cfm at 0.600), I selected a 2.10-inch intake valve and a custom cam with 230/242-degree duration, 0.640-inch lift, and a 112-degree lobe-separation angle.
When it came to exhaust, I wanted to use custom headers and a side-mounted system-all while keeping the noise level acceptable. That isn't easy to accomplish when you have about 600 hp on tap. I knew that I'd have to use the largest Walker Super Turbo mufflers they make, 'cause they have a flow-through design and lots of packing.
In order to use these mufflers, I had to dump the spare tire and under-tank rack, and run an under-body dual system with a custom x-crossover. Then, to get the sidepipes working, I had my welder put in two Quick Time Performance electric cut-out valves. I have a lever switch on the center console that allows me to open the exhaust at any time, even secretly while the engine is off. This works great for surprising folks.
Here's the method I use for exhaust tuning:
1. Apply Alexander Graham Bell's formula for primary-pipe length according to the exhaust valve's opening point.
2. Use his second formula for the primary-pipe diameter.
3. Choose a tri-Y configuration for a broader tuning range of 3,000 rpm on the street.
4. Use ideal mergers to control turbulence.
5. Keep the collector diameter narrow and employ a merge collector to maintain velocity and further minimize turbulence.
6. Apply a heat-retention ceramic coating to keep the temperature up.
7. Use bullet catalytic converters to add just a bit of backpressure and keep the car smelling clean. Without them, too much scavenging at low rpm is likely.
8. Follow that with neck-downs to the exhaust piping and low-restriction mufflers (MagnaFlow, Borla, or DynoMax Super Turbo). Be aware that a 2.5-inch system with mandrel bends will support 500 hp. Sharkee's 600hp system uses 3-inch pipe all the way.
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