Baby Thunder '92 S10 4x4 with 1992 Corvette LT1 Engine, Stealth Conversions

This was built by GM wizard, Scott Leon, at the General Motors Arizona proving grounds. The detail and workmanship on this conversion are first rate and nearly all of the conversion was done with GM parts. The elbow from the throttle-body to the air-cleaner is custom made, and it is a work of art. It is actually made from a few accumulators for the air-conditioner. We can¬t begin to guess how many hours went into making that piece. Stealth Conversions now has a 90° rubber elbow that performs the same functions (see ducting on truck on page 1-4).

Even when using an LT1 engine, this swap is similar to what we recommend. However, the Corvette LT1 engine accessories (air conditioning, power-steering pump, alternator) and brackets must be used for this swap. The accessories used on the Camaro LT1 will not fit the S-Truck 4X4 chassis, but they will fit a 2wd chassis (see chapter 7).

This engine swap is slightly different than what we recommend in that the transmission and transfer case remain in their stock location. The driveshafts remain stock and the evaporator cover remains stock. No modifications were required on the firewall or transmisson tunnel. For cooling, two 150 watt (12 amps) GM fans were mounted in front of the radiator and the 1992 grille was modified for fan clearance. These appear adequate for moderate weather conditions. Remember, the only reason we recommend moving the engine rearward is for improved cooling. Moving the engine rearward requires modifications to the driveshafts, evaporator cover, firewall, transmission tunnel, and shift linkage, but we feel it is necessary with an air-conditioned V8.

Due to the air cleaner position, the 4.3 V6 radiator was offset to the driver's side a couple of inches, and a small battery, group size 70 replaced the larger, group size 78 battery.

Packed under the hood: fourwheel anti-lock takes up lots of space, Stealth Conversions

The engine compartment of "Baby Thunder" is packed full of options and accessories. The fourwheel-anti-lock-brake module takes up a good amount of space. The cruise control, remote oil filter, and the remote power steering reservoir take up even more space. The hose fittings on the air-conditioning compressor were tig welded to route the hoses downward through a small amount of available space. This swap was no small feat.

Due to the "forward" positioning of the engine, the stock 4.3 V6 radiator tank did not allow room for the LT1¬s upper radiator hose. The side tank on the 4.3 S-10 radiator was replaced with the side tank from a 1990-1991 Pontiac Grand Am, GM part #52452789, and a couple of radiator hoses were spliced together to make the upper hose.

If the engine was set back 1 inch, and the radiator mounted forward 1/2 inch as we recommend, a stock 4.3 V6 radiator could probably be used, and a pair of thin 12" electric cooling fans could be installed behind the radiator, as was done on the truck shown on page 1-16. In addition, if the engine was offset towards the passenger's side, an offset oil filter adapter (see page 3-10) could be used instead of the remote oil filter, freeing up some more space. Still, another option is to use the cooling system that was installed on the LT1 powered Blazer shown on page 1-24 and 1-25.

A throttle-body from a 1993 Camaro LT1 engine was installed onto the 1992 Corvette engine. This was done because the throttle-body used on the Corvette has no provisions for the transmission¬s throttle valve cable and cruise control. Those cables are attached to the traction control module that comes standard on all LT1 Corvettes.

Underneath this Baby Thunder is essentially a Syclone with an LT1 engine, Stealth Conversions

Underneath "Baby Thunder", the truck is essentially a Syclone with an LT1 engine. The Syclone uses a full time 4-wheel-drive transfer case from the all-wheel-drive Astro Van or Oldsmobile Bravada. The Syclone, Typhoon and Oldsmobile Bravada also use a different torsion bar crossmember which hangs a bit lower than the standard 4X4 S-Truck torsion bar crossmember, and allows room for a 3 inch exhaust pipe. The transmission crossmember is also unique to the Syclone, Typhoon, and Oldsmobile Bravada. The front driveshaft is also different than a standard 4X4 S-10 in that it uses a constant velocity joint instead of a U-joint. The Syclone also uses a console-mounted Corvette floor shifter with cable actuation, which makes the shifter hook-up easier.

2-1/4" headpipes join into a 3" catalytic converter from a 1994 full-size truck with the 454 V8. We recommend using 2" head pipes on the 4X4 V8 swap because of the tight clearance, but GM's Scott Leon is far more skilled and patient than your average muffler shop.

Notice the license plate, which says "MANUFACTURER" on the bottom. If it didn¬t say that, we would have tried to take credit for building the truck.

From the rear, the truck looks nearly stock, even with the 1993 Corvette tires and wheels. The tires are Goodyear GSC, 255/45ZR17 front, 285/40ZR17 rear. The rims are 8.5x17 front, 9.5x17 rear, and they bolted on with no adapters. The 4-wheel-drive S-10 trucks use different wheel offset than the 2-wheel-drive trucks, so these wheels will not bolt onto a 2-wheel-drive truck unless adapters are used.

The rear suspension was lowered slightly by removing a leaf spring. This also softened the ride slightly. The rear brake drums were replaced with aluminum drums from an IROC Camaro. These changes saved about 30 lbs.

The rear bumper is from an S-10 Blazer and the handle for the spare tire carrier was modified slightly for access to the spare tire. These details are what separates a complete factory type conversion from the novice. This also shows how making a simple change like replacing the bumper can be more work than expected.

The truck weighs 3456 lbs, with a weight distribution of 64/36, front/rear. A GMC Syclone, which is essentially the same vehicle, but with a turbocharged and intercooled 4.3 V6 engine rated at 280 horsepower has a published curb weight of 3526 lbs. The Syclone comes with a tonneau cover and special ground effects body parts which add a few pounds, but it is interesting to note that the Corvette LT1 engine with aluminum heads actually weighs about the same as a 4.3 V6 with a turbocharger and intercooler. The turbocharger and intercooler weigh at least 50 lbs.

This truck is a blast to drive. It is smooth, quiet, and very fast. It runs the 1/4 mile in 13.9 seconds at 98 mph. The all-wheel-drive transfer case makes it possible to do full throttle starts without wheel spin—even in the rain! The LT1 engine idles smoothly and pulls solidly right up to the redline (6000 rpm). Because of the traction, the full throttle 1-2 shift is quite harsh. For example, our ZZ3 powered truck spins the tires on full-throttle 1-2 upshifts, and with Baby Thunder, the four tires grab so hard that it feels like the rear suspension bottoms out during full throttle 1-2 shifts as your head bangs against the headrest during the shift. It's actually kind of fun!