1992 Corvette Race Car, NASA road race prepped, Vorshlag Built

Price: US $7,400.00 Item location: Plano, Texas, United States
  • Make: Chevrolet
  • Model: Corvette
  • Type: Coupe
  • Trim: Race Prepped
  • Year: 1992
  • Mileage: 68,923
  • VIN: 1G1YY23P2N5112284
  • Color: White
  • Engine size: 5.7L LT1
  • Number of cylinders: 8
  • Transmission: 6-speed manual
  • Drive type: RWD
  • Interior color: White
  • Vehicle Title: Clear
  • Want to buy? Contact seller!
Description:

1992 Chevrolet Corvette Race Prepped

This listing is for a Vorshlag built Corvette race car which we campaigned in NASA road racing over the 2015 and 2016 seasons. This C4 Corvette is prepped to the limit of NASA time trial class TTC & PTC road race class. The LT1 engine was fully built by HPR to the limit of the rules, including: forged rods and pistons, balanced rotating assembly, new valvetrain, and a brand new stock camshaft. Fresh triple disc clutch and light flywheel (which removed 50 pounds from drivetrain) is attached to the stock ZF S6-40 6-speed transmission. This 1992 model car has been converted to 1995 GM computer and wiring harness MAF sensor for better EFI tuning.
Front brakes are upgraded to 1996 spec 13" diameter rotors with fresh PBR calipers and Carbotech XP20 pads throughout. Custom Vorshlag built twin Tilton master cylinder brake setup with balance bar replaced problematic OEM master cylinder and plastic brake booster. Fenders are flared for 18x12" wheels and 335mm tires at all 4 corners (which we can sell to you). Professionally built roll cage (which can fit tall people) with recent full repaint inside and out. This car is spotless and beautiful. Car is 150 pounds underweight (2900) for TTC/PTC class but includes a ballast rack for adding weight quickly. Includes a fresh set of Hoosier R7 race tires (only 3 track sessions on the set) and a spare set of identical SSR 17x9.5" wheels. This Corvette needs nothing - turn the key and go race!
details


Price: see current eBay auction!
Miles: Less than 50 track miles since full engine rebuild
Title: Clear Texas title (not registered/inspected)
Engine: Fully rebuilt/forged LT1 engine, 288 whp/354 wtq (de-tuned)
Drivetrain: ZF 6-speed manual, Dana 44, Rear Wheel Drive
Colors: Pure White interior, cage and exterior
Mods: Race prepped for NASA TTC, 17x9.5" SSR wheels, 3" brake cooling,
Cobra Suzuka GT seat, full roll cage/nets, lightweight flywheel and triple disc clutch.
FAST, fully prepped, and ready to race!
vorshlag built cage, interior, safety gear and exterior

This section details the roll cage, safety gear, seat, and other aspects of the interior of the chassis. We also show many details of the exterior of the Corvette below, showing the car being painted in August 2016. Every picture on this page can be clicked for a higher resolution image.

SAFETY - No expense was spared for safety and this Corvette has one of the nicest roll cages we have ever built. This NASA certified 6-point cage is built to the limit of the class and well within the NASA CCR specs using 1.75" dia x .120" wall seamless 1018 DOM steel tubing. The tubing was carefully fitted and 100% TIG welded to over-sized base plates welded to the frame. The main hoop and upper bars built for a tall driver (6'3") with a fixed seat mounted to a reinforced floor. No passenger seat is installed but it can be added easily (weight box mounted to reinforced OEM seat mounts).


INTERIOR - Factory dash is lightened on driver's side and replaced with a custom formed aluminum panel on passenger side (painted with texture black paint to reduce glare). Brand new Momo steering wheel and Halon style fire extinguisher on quick-release mount. Racequip window net, Scroth center net and Cobra/Scroth 6-point racing harness. 14" parabolic center rearview mirror, factory driver's side mirror, and 4" convex passenger side mirror. Factory gauges work and are easy to read, with water, digital oil temp and other details. Wired for AMB transponder (not included), OBD style port, digital volt meter, water proof cig lighter port and dual USB power ports in center stack. Roll cage painted body color with SFI padding and aluminum panels covering all frame access holes. Interior is spotless and very nice.

WEIGHT - This car was weighed many times during construction - the 2840 pound weight was with nearly a full tank and no ballast. We went to great lengths to get the Corvette stripped and well below the class minimum weight. This allowed us to add 150-250 pounds of ballast (depending on fuel level) on the passenger floor. This helped lower the Center of Gravity of the car. The rear glass window was replaced in 2015 by a pre-cut and molded plexiglass unit, droppng 35 pounds off the tail. This attaches to the rear deck via two QuikLatch push-button latches. The original clamshell composite hood and hinges are fully functional and easy to latch.


PAINT WORK - The factory paint was stripped, fully body-worked and painted in August 2016 by our friends at Heritage Collision in Sherman, Texas. They also sanded, prepped, primed and painted the full interior and roll cage.



After this 2+ month body and paint process, we brought the Corvette back to Vorshlag. There we fabricated dash panels, reinstalled the seat, then installed the roll cage padding. Our crew then built the false floor and rear aluminum panels.

The Artic White (no pigment) base / clear paint looks exceptional in person. We challenge you to find a cleaner, better looking, C4 Corvette race car anywhere, at any price.
suspension, brakes, wheels and tires

This section talks about the suspension and brake upgrades that were added to this Corvette. We also show the wheel and tire packages we have used and tested on this car in two different NASA classing configurations. One of the first systems we tackled on this build was the suspension, which we got dialed in fairly quickly and with nothing more than a set of Hoosier R7s and the springs we jumped into NASA TTC class with some effortless wins and big track record drops.

This C4 handles beautifully on track with the included springs and dampers

SUSPENSION - We built this car specifically to race in a NASA Time Trial "points" class called TTC. Running class limited the suspension changes we could legally make, so we concentrated on the most important of all - spring rate improvements. The front spring is a custom built composite VBP 1170 #/in transverse leaf spring, which radically firmed up the front end. The rear spring used was the stiffest factory C4 spring ever made - from the 1984 Z51 package - and it is rated at 500 #/in. The dampers had to be OEM, so we sent the Bilstein monotubes to Bilstein USA for a full rebuild to 1992 factory specs in late 2015. The car includes a 2nd set of more modern Bilstein monotubes, which we purchased new in 2015 and used for only 2 races.

WHEELS AND TIRES - This car came from the factory with 275/40/17 street tires on 17x9.5" wheels. Due to classing restrictions for TTC we ran this car primarily on a lightweight 17x9.5" SSR wheel and 245/40/17 Hoosier R7 race tire. The car comes with one very clean set of these SSRs and a nearly new set of R7s, but a second matching set of SSR wheels is included. We briefly ran this car in TT2 class on an 18x12" Forgestar wheel at all four corners. The testing we did (2 events) used a 335/30/18 Hoosier A6 race tire up front and a wider 345/35/18 rear size. We felt that the TTC suspension limits were not up to the task of the 100mm wider racing tires and undid these changes - a change in damper and spring rate would be needed to run these much higher grip level tires. The flared fenders we have on the car DO fit the wider 335mm tire at all 4 corners, so that upgrade is an option for use in higher NASA classes such as ST1/2/3/4. This set of custom spec'd 18x12" wheels can be provided for an additional cost - the car comes with the 245mm setup.

BRAKE SYSTEM UPGRADE SETUP - The brakes were tricky - the class "points" limited us to the "base trim level" brakes for a 1992-96 Corvette. This 1992 model came with 12" diameter front and rear discs, but after checking the factory manuals we found that the base 1995 and 1996 model Corvettes used an upgraded Z51/Z07 13" dia x 1.10" thick front rotor. We therefore upgraded to new 13" Centric premium front discs and rebuilt (and wider) PBR calipers for the Z51 package as well as added new 12" rear discs and calipers. We had excellent results with Carbotech XP20 pads and the car has a new set installed now. To keep things cool we fabricated a custom front brake cooling backing plate with 3" oval inlets. These are plumbed from 3" NACA ducts under the front bumper cover and through 3" hoses. We have not seen measured front caliper temps above 370°F in hard, sustained laps.

DUAL MASTER CYLINDERS - Even after the above brake upgrades, one lingering reliability issue with the brakes were short lived "rebuilt" brake master cylinders and brake boosters. After the 4th master failed, we switched to a custom dual Tilton master cylinder setup that we designed, CNC machined and assembled at Vorshlag. This setup bolts in place of the factory brake booster and master assembly, includes a pedal effort multiplier for better brake feel, and a cockpit adjustable Tilton balance bar. The factory ABS system was maintained and the new setup works VERY WELL and is reliable. With the larger discs, brake cooling, Tilton masters, Motul brake fluid, and Carbotech pads this car can brake with or better than the most modern Corvettes and delivers lap after lap of fade-free stopping.

Again, this car is built around a rigid NASA TC/PTC rule set, but could easily be run in HPDE events as-is, or with merely a shock and tire upgrade could be very competitive in the new ST4/TT4 class. We built the body to fit around 335/30/18 Hoosiers at all 4 corners, but a 275mm Hoosier would fit with inches to spare. We won a lot of races and obliterated TTC track records with this suspension setup.
drivetrain upgrades

The fully forged race engine is built within the limit of the NASA TT Letter classes, but that doesn't mean we skimped on anything. Forged H-beam Eagle rods and custom spec'd forged Ross pistons are connected to the balanced OEM crank with ARP rod bolts, making the bottom end bullet proof. The factory camshaft was pitted, and no longer made, so the gurus at HPR Engines had the stock cam measured and then custom built a replacement that shares the factory specs in every way. New OEM pushrods, valve springs, and upgraded retainers and keepers were added to the decked and rebuilt factory cylinder heads. This forged, balanced and blue printed engine was not inexpensive and should last for many seasons of racing.

The 1992 model Corvette was the first year of the LT1 engine, and had a unique speed density air metering system and a somewhat crude engine computer. After fighting with problematic computer and old engine harness, we upgraded to a rebuilt 1995 Corvette computer, a new OEM spec engine wiring harness, and MAF unit. The computer and MAF change were class legal but the correct rubber intake hose was no longer available so we used an aftermarket unit and took 1 point for a custom cod air kit. To make that point worthwhile we then modified the factory air box to triple the surface area for incoming air. A new MSD Optispark style distributor fires the Taylor 409 series spark plug wires. A custom aluminum, double thick, radiator was modified to fit the factory radiator ducting and provides cool temps under all conditions. The A/C compressor was replaced with a billet TPIS A/C delete kit, maintaining the factory belt routing.


The QuarterMaster 7.25" diameter triple disc clutch and pressure plate assembly includes a lightweight flywheel which shaved 50 pounds off the factory dual mass flywheel and single disc clutch. This alone makes the engine rev up and down VERY quickly, which makes shifting easier and frees up drivetrain losses. A McLeod hydraulic throw-out bearing was added and setup to actuate the triple disc clutch. The fresh engine and very lightweight clutch setup made 305 whp and 345 wtq, which had to be de-tuned to meet the class limit 286 whp. We added a vented Peterson oil / air separator and catch can plumbed to both valve covers.


There are $10,000 in receipts for the engine, clutch, wiring, computer, ignition system, cooling system, and other drivetrain components, all of which are very fresh. The engine has less than 50 miles on it since it was rebuilt. These power upgrades have been custom dyno tuned by True Street Motorsports, and the engine had to be de-tuned by nearly 20 whp for TTC class limits.

With unrestricted tuning the engine made 305 whp on a chassis dyno - using a factory camshaft, breathing through a stock throttle body, and exhausting through factory manifolds, catalysts, mufflers and piping. This engine could easily produce another 90-100 whp with an exhaust system and camshaft upgrade alone, and reworked cylinder heads could unleash even more. The road to ST4/TT4 would be an easy one.
contact info

This one-of-a-kind C4 Corvette road race car is now being auctioned on eBay. If someone asked us to build a similar C4 Corvette we would charge between $35-40,000 to make another. This car was fully painted in late 2016, then meticulously detailed and photographed, and has not been raced since. Feel free to call us (972-422-7170) or email (sales@vorshlag.com) with any questions about the car. You can setup a time to view the car during the auction.

This is one of those rare race cars that is being sold in a meticulously clean state, inside, out and underhood. It looks damn good as it sits, and even more amazing with the 335mm tire / 18x12" wheel combo. We would LOVE to keep this car and racing it next season (in TTC or TT4) but since we make almost no parts for C4 Corvettes, this car doesn't help us for marketing our business. Project Dangerzone recently ran a 1:21 lap at MSR-Cresson on the 1.7 mile CCW course on a 245mm Hoosier R7, carrying ballast, and does this easily and reliably.

The exterior matches the "bare white" images above, with the 5-spoke wheels SSR wheels and a white painted roof panel. We removed all of the racing decals prior to paint. All work on the car has been done at Vorshlag by our trained technicians, except for the custom dyno engine tuning and paint work. Payment accepted includes cash or cashier's check with a minimum $500 payment within 24 hours of auction close.