Fully assembled and sitting on the engine dyno, our new 383 stroker LS motor looks downright mean. Then again, looking cool is pointless if you’re not making serious horsepower, so follow along to see how we accomplished that goal.
In part one of our build, we introduced you to our 4.8L Vortec V-8 stroker engine project. At Superior Automotive Engineering in Placentia, California, the LY2 iron block was stripped down, cleaned, and precisely machined to its new, larger displacement: 383 ci. We left off just as the block was sprayed in a two-tone gray and red-orange enamel paint scheme, and now we’ll be moving on to install all the upgraded internal components we’ve been stockpiling.
So, you may ask, what exactly will we be using inside our new 383 LS motor? First, we’ve got the Eagle 383 rotating assembly you caught a glimpse of in part one (PN 12922, $2,299 at CNC-Motorsports.com). The package includes an Eagle 4340 forged-steel crank with optional oil-shedding ESP Armor coating, Eagle 6.125-inch forged H-beam rods, and Mahle 3.905-inch bore forged pistons with a -26cc dish and valve reliefs.
Next, we called up Comp Cams, which sent out an XFI XE-R hydraulic roller camshaft (PN 54-446-11, $399 direct from Comp), Hi-Tech pushrods (PN 8406-16, $189), short-travel race lifters (PN 875-16, $228), and Ultra-Gold rocker arms (PN 19024-16, $505). Comp also included a few other goodies, such as valve covers and a timing kit, but we’ll get to those later. FAST sent us its LSX 92mm intake manifold with a Big Mouth throttle body (PN 54039BK, $1,506), billet fuel rail kit (PN 54023, $220), and 36 lb/hr injectors (PN 303608, $331). Finally, RHS sent over a pair of Pro Action cathedral-port heads (PN 54302, $819 each at jegs.com), and ARP supplied all-new hardware for our engine and accessories.
After it was all assembled, the crew at Superior Automotive bolted the engine up to their in-house engine dynamometer. On the dyno, our new build was warmed up, broken in, and run at full-throttle to check power output. Read on to see the assembly process and find out how much power this 383 stroker LS engine made.
1. Part one of our build left us with a freshly machined and painted block. To begin assembly, the main bearings were installed and greased. Then, the Eagle crank with oil-shedding ESP Armor and longer 4.00-inch-stroke length was set in place.
2. More main bearings were placed on the main caps, which were installed atop the crank with new ARP studs. All hardware was carefully torqued to ARP’s specs: 60 ft-lb for the inner studs, 50 ft-lb for the outer studs, and 20 ft-lb for the side bolts.
3. Using a magnetic gauge and two flathead screwdrivers, Jorge Jabaz checked for any endplay or movement in the crank. Even a tiny amount of extra play could cause a catastrophic failure later, so confirming the crank is secure put our minds at ease.
4. Next, we began assembling the Eagle 6.125-inch forged H-beam rods and Mahle 3.905-inch bore forged pistons. Retaining rings were inserted on the sides of each piston, attaching it to the pin and connecting rod.
5. Once the pistons and rods were joined, all three sets of piston rings were gapped and installed, and we were ready to drop everything into the cylinders.
6. After greasing and installing bearings on each rod, a mallet handle and piston installation sleeve were used to press all eight pistons into the cylinders.
7. The rod ends were fit with more bearings, greased, and set in place around the crankshaft. The included ARP rod bolts were torqued to 63 ft-lb.
8. Cam bearings were installed, and the Comp Cams XFI XE-R hydraulic roller camshaft was slid into the block. The cam’s .595/.598 lift and 281/283 duration will give our build plenty of top-end power for the track, and its 112-degree LSA will retain a streetable idle.
9. With the camshaft installed, we bolted on a Comp Cams thrust plate (PN 5400TP-KIT, $99 direct from Comp), and then added a Comp adjustable timing chain set (PN 3158KT, $175). The cam timing was then advanced 4 degrees, which will lower our powerband slightly and improve off-the-line acceleration.
10. When installing and aligning the oil pump on an LS engine, you’ve got two options: buy the expensive factory installation tool from GM, or do what we did here. Ultra-thin 0.0015-gauge steel shims were used to align the gears while the bolts on the housing were torqued down, centering the pump.