Choosing which engine to build for your project Camaro is serious business. After all, the engine is an expensive part of your build and it’s not something you want to waste money on by not getting it right the first time. In deciding which way to go, the first order of business is getting a firm grip on how you plan on driving the car. If it’s just going to be a cruiser, then something in close-to-stock form is the way to go. If drag racing is your thing, then building a mill that spins high should be the target. However, if you’re like us, then you might have your sights set on whipping around an autocross or road course. In this realm, horsepower numbers need to be set aside and the focus put on the real star of the show: torque. And not just any torque, but low- and mid-range twist. Gobs of luscious torque in the lower half of the rpm range is what gets your car moving and helps you accelerate out of a corner.
Our second-gen project, Orange Krate, is destined to spend a good amount of it’s time pegging the g-meter at various driving events, so we knew that we wanted its engine to have more than just a heaping spoonful of torque. We also realized that it would be seeing plenty of street miles as well, so building some lumpy and obnoxious engine was a non-starter. When we think great power combined with silky sweet street manners, we come up with one platform: the GM line of LS engines. As a bonus, this performance comes wrapped in a lightweight package that can still knock down great mileage numbers when teamed up with the Tremec TKO-600 five-speed overdrive trans we’ll be running from Hurst Driveline Conversions.
With the choice to go LS clear, we just needed to decide on which particular engine to go with. We wanted torque, and nothing makes torque better than displacement. Currently, the biggest aluminum block offered by GM, besides the astronomically priced LS7, is the 376ci (that’s 6.2L for those stuck in metric land) block. Since we’re building from scratch, we also figured we could ratchet up those cubes by going the stroker route. After all, a stroker crank costs only a few bucks more than a forged 3.62-inch factory stroke version, and the extra cubes equates to more torque potential. For a displacement target, we decided to go with a 416, which is a 4-inch stroke teamed with a 4.070-inch bore. Now we’ve see people turn LS3s into 427s by going with a 4.125-inch stroke, but on a factory sleeve, that’s pushing things to the ragged edge and requires a crazy short piston. Again, our plan for Orange Krate is to heap on tons of really hard miles and we felt it was a good idea to trade in some cubes for peace of mind and longevity. So with a plan in mind, and a truck full of parts, we headed over to Turn Key Engine Supply in Oceanside, California, to ratchet together a powerplant for our ’71 project car.
The starting point for our 416 stroker was this block from GM Performance Parts (PN 12621769, $1,350). For our build, Turn Key Engine Supply simply honed out the bores to 4.070 and we were good to go.
After laying out all the parts, we started mating the Wiseco pistons (PN K464X7, $780) to the SCAT Ultra Q-Lite connecting rods (PN 2-350-6125-2100-QLS, $450) using the included spiral locks. The 6.125-inch, 4340 forged H-beam rods came with special doweled caps for a precision fit and included ARP 8740 fasteners.
This process was repeated eight times, and then we went about file-fitting and installing the ring packs. Organization here is imperative since it’s a real “buzz kill” to find out your pistons are on backwards. The extra hole in each SCAT rod was something we hadn’t seen before. According to SCAT it reduces weight without compromising strength. The Wiseco 2618 alloy slugs came with coated skirts, chromoly pins, and are specifically designed to clear the reluctor wheel in stroker applications like ours.
The first part to find its way into our GMPP block was this hydraulic roller stick from COMP. We want good power, but street manners are also important, so we came up with a cam profile of 235/251 with lift of .621/.624 and a 113 LSA.
Most of our displacement gain came from increasing the stroke, and the key part was this SCAT forged 4340 standard-weight crank (PN 4-LS1-4000-6125-58, $950). Features include straight shot and chamfered oil holes, Nitride hardening for better wear, and lightening holes in all the rod throws. Before shipping, it was also micro-polished and fully inspected at SCAT.
With the SCAT crank in place, we went about securing it in place with a main stud kit from ARP (PN234-5608, $227).
Then, one by one, we slid the piston/rod assemblies into place after giving each bore a light coat of oil. The Wiseco Flow-dome design mirrors the face of the valves and doesn’t shroud them or create a tall dome that impedes combustion. Incoming charge past the intake valve and outgoing exhaust past the exhaust valve doesn’t get caught in the void underneath the valve and flows smoothly past it.
The ARP fasteners included with the SCAT rods were then torqued to 75 ft-lbs. You can also spot our crank’s 58x reluctor wheel, which we chose so our engine would be compatible with the GMPP computer and harness kit we’ll be running.
With stroker engines, one of the bigger killers is piston rock at bottom-dead-center (BDC). The basic premise is that the piston must still be at full diameter when it reaches BDC even if some of the skirt is hanging out the bottom of the bore. This way the piston won’t wobble and tear itself apart as it’s forced up the bore and past the sharp edges at the bottom of the cylinder. It’s important that the piston skirt is at full diameter at BDC and the necessary taper must be introduced at a point above this. Reducing piston rock also keeps the rings perpendicular to the bore and for better oil control.
To handle our stroker’s oiling needs, we installed this pump from Moroso (PN 22120). Besides putting out large volumes of oil, the forward-facing bolts are inset to the face. This makes running a double-roller timing chain much easier since there’s no need to shim out the timing cover. In our case, we’re running GM sprockets along with a stronger chain from COMP.
Our oil pan utilizes the pick-up tube (GM PN 12558251) and windage tray (GM PN 12558253) from a ’93- 02 LS1-powered Camaro. To clear the 4-inch stroke of the crank, we spaced the windage tray down by using three washers at all of the attachment points. We also needed to clear (ie, grind) the back of the windage tray a bit so that the Canton pan could come forward and line up with the bolt holes.
This pan from Canton (PN 13-270A, $545) offers tons of frame clearance along with great oil control. It has a 6.5-quart capacity and incorporates a fully fabricated aluminum construction. The key feature of this pan is the twin trap-door baffling system. The purpose of this system is to keep oil around the pick-up during high-g cornering. In addition to the trapdoors, the Canton pan also has a removable anti-slosh baffle.
Eventually this engine will be running Vintage Air’s Front Runner system, so we figured now was the perfect time to install the ATI Super Damper included in the kit. To secure the damper, we used a very large ARP bolt (PN 234-2503, $29). Unlike the factory offering, it can be reused over and over.
Before the heads could go on we needed to install the lifters along with the GM plastic lifter trays. We went with offerings from COMP (PN 850-16, $210) since they drop in just like the factory lifters and are easy on the wallet.
If you want to make good power, then you need a great set of heads. These CNC-ported L92 heads (PN SD8765, $799 ea.) from Scoggin Dickey Parts Center (SDPC) feature 70cc combustion chambers, stock valves, Manley locks, and titanium retainers. On the intake side, these heads flow 345 cfm at .600 and 350 cfm at .700 lift according to the gearheads at SDPC.
We then went about installing the SDPC heads using GM MLS gaskets (PN 12610046).
For head fasteners, we went with reusable—and stronger than the torque-to-yield bolts—head studs from ARP (PN 234-4317, $296) and torqued them to the specifications called for in the kit.
These are LS3-style heads so the rockers needed to be the proper type with offset intakes. These full roller pieces from Yella Terra (PN YT-6668, $498) are both lightweight and are some of the strongest rockers out there. The extruded, heat-treated, aluminum rockers are stud mounted and feature strong cross shafts for better stability at high rpm. Best of all, they fit without any grinding of the head or the rockers.
For an intake we decided to run a 102mm unit from FAST. This polymer intake is modular, so it’s easy to port match if you’re in the mood to whittle on some plastic. To keep the oil in the engine, and add a whole lot of style points, we picked up a set of these new cast-aluminum valve covers from GM Performance Parts. They came powdercoated silver and fully baffled. The kit even included GM gaskets and chrome bolts.
To properly feed our 416 LS3, we also installed set of FAST billet fuel rails (PN 146027-KIT, $193) along with some 46-lb FAST LS2-style low-impedance injectors (PN 30462-8, $396). The rails feature a larger internal diameter than factory rails. This helps dampen pulses and insures the injectors never run dry. The fuel rail kit included #8 fittings along with the proper O-rings.
And that’s a wrap! To get a nice money shot we tossed on a water pump, some coated headers, and GM throttle-by-wire throttle body. A new engine is a beautiful thing.
To see what our new mill would put out, we hauled it over to Westech Performance in Mira Loma, California, for some quality time on their Superflow 902 dyno. After filling the dyno’s tank with some of the best 91 octane California swill around, Steve Brule started running the 416 though the break-in runs.
Before firing up the 416, we poured in 6 quarts of Red Line SAE 5W30 high-performance oil, along with half a bottle of their break-in additive.
After a few pulls, Westech’s EFI tuner, Ernie Mena, had the 416 mill dialed in with a best pull of 612 hp and 566 lb-ft of torque. At 3,000 rpm, the torque was 431 pounds with peak at 5,200. When the engine was making peak horsepower at 6,400 rpm it was still pumping out 502 pounds of twist. That makes for a nice flat torque curve that should serve Orange Krate well.