S10 Swap, Part 3. Project ZZ3—OUR QUICKEST TRUCK


Project ZZ3, Fastest Stealth Conversion's S10 V8 Swap

Note: The engine shown in this truck is no longer available from GM. It has been replaced by a slightly more powerful engine called a ZZ4. It is no longer possible to do this exact swap because some of the parts are no longer available. We continue to show this truck because it shows what can be accomplished while still being legal. We believe that similar performance can be achieved with smog-legal aftermarket performance parts. Today, it is possible to purchase smog legal high-performance cylinder heads, camshafts, intake manifolds. A 350 Truck TBI engine with the Edelbrock performance package (aluminum cylinder heads, camshaft -- with matching computer chip -- and intake manifold) is probably the most comparable smog-legal package.

The engine package installed in this 1987 truck is the "5.7 liter High Output Camaro Conversion" (GM part #10185077) which is rated at 308 horsepower in smog legal trim for the 1982-1987 Camaros and Firebirds. It was developed by GM Motorsports Engineer Mark McPhail for the 1982–1987 Camaro/Firebird. Because California smog laws allow engine swaps as long as all of the emissions controls are installed and operating, this engine package (which requires the 700-R4 transmission) is also legal in 1982–1987 S-Trucks (more information on smog laws is in chapter 14). By the way, this is JTR's truck. It's a real truck (a GMC, not a Chevy!).

The engine in this engine package is the ZZ3 345 horsepower High Output "crate" motor. The ZZ3 has aluminum heads, aluminum intake manifold, high lift roller cam, forged steel crank, 4-bolt mains, "pink rods", and hypereutectic pistons with a compression ratio of nearly 10:1. The package includes a cold air induction dual-snorkel air-cleaner from a 1983–1985 Camaro with the L69 engine, dual catalytic converters from a 1990–1992 Camaro with the 350 TPI engine, a Holley fuel pressure regulator, specially calibrated carburetor secondary rods, and special transmission parts that increase the shift firmness and improve the durability of the 700-R4 transmission when used with the ZZ3 engine. The parts list and instructions is too long to put in this manual and is available from GM as part #24502463. The information on the transmission modifications is very important because it makes the package work so well with proper shift points and firmness.

ZZ3 345 horsepower High Output "crate" motor, Stealth Conversions

The "smog equipment" is not totally responsible for reducing the horsepower rating from the ZZ3's original 345 down to 308 (37 horsepower). According to GM engineers, the Camaro's low hood line requires a short air cleaner which is responsible for about 8 horsepower. The Camaro's H.O. exhaust manifolds are responsible for another 20 horsepower, compared to dyno headers. The dual catalytic converters reduce output less than 10 horsepower, and the smog pump consumes less than 1 horsepower. The S-Truck has room for a taller air cleaner (from a Monte Carlo SS), but the exhaust manifolds required for the S-Truck chassis may drop a few horsepower compared to the Camaro H.O. exhaust manifolds, so overall, the Camaro H.O. conversion package in the S-Truck is very comparable to the Camaro's 308 emissions legal horsepower.

To make the finished installation look simple and uncluttered, we intentionally chose a truck without air-conditioning and we set the engine back 1-1/4". This required reshaping the transmission tunnel with a hammer, and it required massaging the firewall for the automatic transmission shifter on the steering column. Additionally, we installed a set of headers for evaluation purposes (We prefer the cast-iron exhaust manifolds which are now on the truck!). Even with the engine set-back 1-1/4", the big HEI distributor required no firewall modifications. This conversion took a very long time to complete. Making it look easy, was hard.

We always install an MSD™ Soft Touch™ Rev Control to our stick-shift vehicles but it was also installed onto the ZZ3 truck. With previous bad experiences caused by "over-enthusiastic" drivers damaging engines, we didn't want to risk hurting the H.O. engine. The rev limiter costs less than $100, and we believe it should be installed on every high-performance engine. It's amazing to us how some people, after driving our vehicles, would comment on the "high speed misfire." What they were really telling us is that the rev-limiter saved another engine from damage.

Dual exhaust underneath ZZ3 truck, Stealth Conversions

Underneath the ZZ3 truck is a 2-1/4" dual exhaust system. Dual catalytic converters were a part of the 5.7 liter H.O. Camaro Conversion package, and were legal in this application (The headpipes and converters from the Camaro package will not fit the S-Truck V8 conversion. This truck has custom made headpipes, and universal replacement high-flow catalytic converters). Flowmaster two-chamber mufflers are used, and an exhaust crossover pipe behind the catalytic converters smooths the sound out the tailpipes.

To reduce the heat going into the passenger compartment, the headpipes are wrapped with Thermo-Tec® exhaust insulation wrap, and Thermo-Tec® aluminized heat barrier is attached to the underside of the cab, above the exhaust.

Originally it was decided to keep the truck as light as possible for best performance. The truck had few options, and the aluminum heads and intake manifold used on the ZZ3 engine saved about 60 lbs compared to a "normal" V8 engine. An Edelbrock long-style aluminum water pump (the only long-style auminum water pump on the market that will work with the stock Camaro accessories) dropped 6 lbs off the front end, a 1993 Camaro LT1 gear reduction starter saved another 9 lbs. To improve weight distribution, the battery was relocated behind the right rear wheel. Aluminum brake drums off an IROC Camaro saved another 9 lbs.

Without power steering and power brakes, the truck weighed less than 3000 lbs with the 20 gallon tank full of fuel, so with over 300 horsepower, it should have been a fun and wildly fast truck.

Wildly fast?‹Yes! Fun?‹Not really.

The power overwhelmed the stock 4-cylinder shocks, front springs, and lack of anti-sway bars. The manual steering was too heavy and too slow. The non-power assist brakes took too much effort. And perhaps most frustrating of all was that without a limited-slip differential, it would spin the right rear tire all too easily, severely limiting acceleration.

In other words, there was still more work to do!

Suspension parts from a 1996-2000 ZQ8 equipped 2WD S-10 truck were installed on the 1987 truck. The ZQ8 parts list includes stiffer shocks, 1.3" diameter front swaybar, rear sway bar, front and rear springs, a quick ratio steering box. The parts are listed in the Chevrolet Performance Parts Catalog, which is available from your Chevrolet dealer.

Bell Tech Drop spindles and lowering blocks also help lower the truck. Power-steering and power-brakes were added, along with the rear-wheel anti-lock brake system from a 1989 S-Truck. The power steering and power brakes made the truck easier to drive, and the suspension parts made the truck handle better, but the ZQ8 parts made the ride stiffer. Some people like the stiffer ride, some people don't. If you want sway bars that are stiffer than the ZQ8 parts, Hotchkis Performance makes front and rear sway bars that are similar to the ZQ8 parts, but thicker and stiffer.

To improve drivetrain strength and traction, a 4.3 S-Truck rear axle assembly (7-5/8" ring gear compared to the stock 7-1/2" ring gear) and an Auburn limited-slip differential were installed. The limited-slip differential dramatically improved the truck's ability to accelerate out of corners without spinning the inside rear tire. With street tires, the Auburn limited-slip differential dropped the 0-60 mph time to 5.7 seconds, compared to 6.3 seconds without it.

Even though the above suspension and brake modifications added weight, the truck became fun! It corners, it accelerates, and it stops with the best of them. The engine makes the truck so fun that the MSD™ Rev Limiter is constantly being put to use. At a steady 65 mph, the lightweight truck gets 22 mpg with its 3.42 gears. But because of the happy feet we get driving it, the fuel consumption has been averaging about 14 mpg.

Our best 1/4 mile run on street tires was a 13.9 at 105 mph on a 100 degree F day with the headers, but without the limited-slip differential. With slicks, the limited-slip differential and cooler weather (but with the cast-iron exhaust manifolds, power-steering, power brakes, and swaybar) a 260 lb magazine editor ran a 13.3 second quarter mile at over 102 mph. Four years later, with a quieter (more restrictive) exhaust, an engine-driven fan, and more weight (heavier tires and wheels, hard tonneau cover, body mods, sound-deadening, rear bumper, etc), the truck only ran 98 mph in the quarter mile. Because the truck does not have a tach, all runs were done with the shifter in drive, shifting at about 5300 rpm. The GM engineer who developed the ZZ3 package says it would run faster if shifted at 5800 rpm.