Mini-trucks are typically associated with being the primary modes of transportation for farm workers and delivery drivers' not the stuff hot rods are made of. Japan may have invented mini-trucks, but America perfected them. GM currently offers small pickups from both of its truck lines—Chevrolet and GMC—each model sharing an essentially identical platform, with only minor trim pieces setting them apart. These little pickups offer affordable utilitarian fun, and, fortunately for the "I can't afford a new full-size pickup and refuse to drive anything but a Chevy" crowd, used ones can be bought for a song. So why doesn't every faithful Bow Tie fan have one of these little tykes? Because they lack the ummph that makes driving a real truck fun. GM chose to equip its mini-trucks with only four-bangers and V-6s, all of which are seriously lacking in the torque/testosterone department.
Thankfully, the V-8 power Gods are watching over the Chevy faithful and have provided a way to snap a small-block into these trucks to make them run with the best of their big brothers. Legend has it that in spite of the relatively tight package, the S-trucks are willing to accept a V-8 and retain all factory accessories, like A/C and power steering, to keep the little big-power pickup comfortable. We sent a group of fearless power mercenaries into the engine-swapping netherworld in search of information on these S-10 V-8 cruisers. They returned, presenting us with a single copy of the Chevrolet S-10 Truck V-8 Conversion Manual from JTR Publishing, stating this was all we would need to complete our quest.
JTR is a small publishing company in Northern California that has researched this swap for over a decade and performed several V-8 conversions in order to test its theories. The JTR manual is now in its 14th edition and covers every aspect of the swap and every modification you'll need to perform to drop a small-block into your small truck. Fortunately for you, the manual can be purchased from Summit Racing (PN JTR-S10, $28.69), so hiring unreliable spies won't be necessary. If you're considering stuffing a V-8 into your S-truck, or just looking for a few ways to improve or modify it, then this is the bible for you.
What's It Going To Take?
Swapping a V-8 into your S-truck will not be cheap or easy, but it will be worth it. JTR told us that too many swaps are never completed because the truck's owners either expected a quick turnaround or were looking to save a buck. Both of these items can be left off your "Things to do" list when planning for this swap. If you properly prepare for your swap and collect the components needed ahead of time, the swap will be completed and you'll be driving your V-8 powered mini-truck in short order. JTR has found that the best and easiest V-8 conversions always begin with a complete engine and transmission, exhaust manifolds with head pipes, and all accessories extracted from the same donor car. While swapping in your own custom-built, fire-breathing small-block is possible, JTR recommends using a stock engine and all of its factory components to make your first swap easier. Keep in mind that your S-truck's stock anemic four-banger may only be making about 100 hp, and swapping in a stock 205hp Camaro engine will make that little truck run like a stallion.
The first unavoidable truth is that swapping in a V-8 will add weight to your truck, with most of it over the front tires. Since the factory S-truck's suspension was never designed to cradle an iron V-8, it will welcome the addition of stiffer coilsprings and new front shock absorbers. GM offers a performance suspension upgrade for '94 and newer two-wheel-drive S-trucks under RPO ZQ8, which includes new front and rear performance springs, Bilstein shocks, a new steering gear, new front and rear sway bars, and all the attaching hardware. This package is known as the S-truck Extreme Sport Suspension and is sold under GM Performance Parts PN 12371217. Without this suspension upgrade, your V-8 S-truck will handle terribly and probably bottom out on every bump. Four-wheel-drive S-trucks can be improved after the swap by installing aftermarket shock absorbers and tightening the factory front torsion bars to reestablish the correct ride height. An iron-headed small-block and 700-R4 trans will add approximately 200 pounds to the nose of your already heavy 3,600-pound (average 2WD weight) pickup. In addition, the V-8 puts more weight ahead of the front tires while moving 20 pounds of rear weight forward, lightening the rear end, which furthers complicates traction problems.
Cooling and exhaust are two of the biggest problems associated with swapping a V-8 into the S-truck. Fortunately, JTR has found some factory components to make the swap as hassle free as possible. While there are currently several aftermarket manufacturers offering swap kits using headers designed to fit the S-truck chassis, JTR has tested most of them and claims that headers may require some extra fabrication/modifications or they just won't fit. JTR has found that the factory exhaust manifolds from a low-performance '82-'92 Camaro/Firebird TBI 5.0L V-8 make the swap easy.
When searching the scrap yards for these iron nuggets, be careful not to pull the manifolds from a TPI or L69 5.0 HO engine or from a Corvette because they won't fit. The best news is that the TBI exhaust manifolds are cheap and plentiful in scrap yards everywhere. When removing the manifolds, be sure to also keep a section of exhaust head pipe from the donor Camaro so the muffler shop has a starting point for the new exhaust system. The S-trucks have enough room beneath the bed for a muffler shop to mount dual-performance mufflers side-by-side vertically, so you can run true dual exhaust out the back. Keeping a V-8 powered S-truck cool can be tough if it is not properly addressed during the swap. The good news is that a stock, high-efficiency Corvette radiator can be bolted in with little modification. JTR has tested four different aftermarket custom-built radiators, with moderate success, but found that the '85-'89 Corvette HD radiator is the best at cooling a V-8 S-truck.
This aluminum radiator features plastic side tanks and is quite similar to the stock radiator used in all '87 and newer S-trucks, which is why it fits and cools so well. It's very light, weighing about 10 pounds, and its high-efficiency aluminum core cools extremely well, even in an A/C-equipped truck.
The Corvette radiator is also very thin, offering a inch more clearance between the fan and radiator when compared to a typical 2-inch-thick brass radiator most custom shops would build for this type of swap. A inch may not sound like much, but JTR claims it makes a huge difference in cooling effectiveness because the engine-driven fan can have more pitch, which increases airflow through the radiator. The -inch gain in clearance requires some hammering on the radiator core support so that the side tanks sit far enough forward (see photos). The Corvette radiator is also equipped with an automatic transmission oil cooler, which helps because there is very little room to install an auxiliary cooler in front of the radiator. JTR recommends using either an 18-inch-diameter aftermarket flex fan or, after modifying the core support further (see photos), running a factory clutch fan to cut down on highway fan noise.
Things That Can Break
If you're wondering whether the stock rearend would hold up behind a torquey V-8, the answer is probably no. GM's weak-duckling 7- -inch rearend came standard in most S-trucks, and if you're swapping in a V-8 you should track down an '88 or newer 4.3-liter V-6 S-truck and swap its 7-5/8-inch rearend into your truck. Or, better still, if you can find a '95 or newer S-truck equipped with the high-output L35 V-6 and five-speed trans at the junk yard, they were equipped with a much stronger 8- -inch rear that can take lots of abuse. The 8- -inch rearend can be quickly identified by the way its axle tubes get larger in diameter where they meet the center section. The driveshaft will need to be shortened when installing the 8- -inch rearend. Beware that all S-truck rearends are not interchangeable. S-truck 2WD housings are 4 inches narrower than their 4x4 counterpart, and the ZR2 4x4 Off-Road option featured wider wheels, so its rearend is an additional 4 inches wider—making it 8 inches wider than a 2WD housing.
A new rearend will give you strength, but you're bound to experience traction difficulties after swapping in a V-8, due to the lack of weight over the rear tires in all S-trucks. GM knew of its traction problems and added a horizontal shock absorber to S-trucks equipped with a V-6 and ZQ8 suspension package to control wheelhop. This worked so well that the horizontal shock was later installed on all V-6 five-speed S-trucks built after 1996, making it a relatively easy part to find used. The horizontal shock brackets can be added to earlier trucks by simply drilling a few holes and bolting them on. However, the horizontal shock will interfere with the factory muffler if it's left in the stock location, so a shorter muffler must be installed.
Good or bad, most states have followed California's lead when mandating their own emissions standards. Currently, it is legal to perform engine swaps in California if certain criteria are met. Most importantly, the new engine you're swapping in must be from a GM vehicle of the same year or newer than the vehicle you're swapping it into. The new engine must retain all of its original, functioning emissions equipment, and any aftermarket performance equipment that has been installed must have a California E.O. number assigned to it to keep your swap legal. You also can't swap a heavy-duty truck V-8 (trucks over 6,000 pounds GVW) into your S-truck because HD truck engines had less stringent emissions standards than light-duty trucks, but passenger car V-8s are OK.
In order to get your engine swap approved, you need to go to a Referee Station and pay about $30 to have your vehicle inspected. The referee will inspect your installation to see if you used the same or newer year engine. He'll check operation of all the emissions equipment, and if it passes inspection he'll slap an "Engine Identification" sticker on your doorjamb, meaning a legal record of your approved engine swap is always on the vehicle. Contact your local DMV office and ask for the number of a Referee Station near you. The person answering the phone may ask why you need to go to a referee, and your answer should be "engine change." If you say "engine swap" or " V-8 conversion," you'll confuse the employee on the other end of the line who has the power to cause you hours of endless grief, so remember to only speak in language they're familiar with.
There Is More
We've had the opportunity to drive several V-8 powered S-trucks, and, when done properly, the trucks run so well and are so comfortable that you'd never know it was anything the factory didn't intend. The benefits of using a stock engine really shine with the ease of starting and smooth running a V-8 S-truck displays. With the factory A/C and power steering intact, your V-8 powered mini-truck can be comfortable and fun to drive. JTR claims to have knocked down as much as 20 mpg in its V-8 powered S-trucks but, of course, that's in direct correlation to how heavy your right foot is. And believe us when we tell you that the way your V-8 S-truck will accelerate sure doesn't lend itself to grandma-style merging onto the freeway. There is much more information on performing these swaps available than we were able to touch upon here. There are also several sources for V-8 swap parts, including Advanced Adapters, Hooker Headers, Russ's Rods, Stealth Conversions, and Southbay Motorsports Designs, all of which offer parts, kits, or information to help with converting the little S-trucks.