Part 2: Building Big Horsepower For The Superburb
Some of you may remember the Jan. '07 issue, where we began assembling components for a stroked 383 Chevy small-block engine. The idea back then was to build a California smog-legal engine that could produce somewhere in the neighborhood of 500 rear-wheel horsepower on pump gas. Originally, we planned to drop this mill into a blue '92 Chevy 1/2-ton that was first shown in "The Lowdown on Four-Wheel-drive Conversions" (June '05). Unfortunately, in the passing years that particular truck was sold by its owner, Off Road Unlimited, before we had a chance to install and test the new engine. Like so many unfinished projects without a good home, Stover's Stroker was put on the back burner until a suitable donor vehicle was attained. Lo and behold, Four Wheeler's unfinished project SuperBurb popped back up on the radar. We discovered it beneath a thick layer of dust and cobwebs in the side yard of its former owner's parents' place in Malibu, California. Incidentally, the truck was for sale, so quick-thinking Stover purchased it with the intent of bringing it back to these pages. Over the past year and a half, we've received a ton of mail about the disappearance of both Stover's Stroker and the SuperBurb, so we're pleased to reintroduce both projects with an updated build strategy and even greater performance goals. In the coming months, you can expect to see us marry the two buildups, netting a super Suburban like no other.
New Project Criteria
1. 6,500-rpm redline
2. Good driveability
4. 500 rear-wheel horsepower, 500-lb-ft of torque
5. Longevity-we want it to last
1. Overland adventuremobile
2. Plenty of secure storage for equipment and gear
3. Dependable performance for multi-week trips
4. Self-contained camping with sleeping quarters for up to four adults
5. Classic styling with high-tech underpinnings
Back in 2004 the SuperBurb received a brand-new 383 HT GM Performance powerplant. That turnkey crate engine is still available today and offers high torque over a very broad and driveable rpm range (2,500 to 4,000). So why are we building a different stroker, you ask? Well, while the 383 HT is quite capable in its own right (340 hp at 4,500 rpm, 435 lb-ft of torque at 4,000 rpm), our sinister plan included 35-inch rubber, a 9,000-pound gross vehicle weight, and the ability to keep up with modern diesel pickups on longer hillclimbs. What can we say, we're power snobs.
The first step to any good engine buildup is blueprinting and balancing. Blueprinting, by definition, means taking the time to recheck and remachine if necessary, engine components to optimal tolerances to effectively achieve better durability. The balancing aspect requires engine builders to carefully weigh each and every component of the rotational assembly. The idea is to make the crankshaft counterweights equal to the pistons, wristpins, rings, and small end of the connecting rod. Most builders use spin balancers to evaluate rotational forces at a given rpm. Most connecting rods, pistons, and wristpins are all sold as a matched set to make the process easier. Larry Kleen of Mustang Ranch in Santa Clara, California, performed our blueprint and balancing job. This shot shows an area where Kleen added weld to the crankshaft counterweight to achieve proper balance.
This photo shows the nice cross-hatching Ganz made in the cylinder walls after boring out each cylinder. The cross-hatched pattern is made using a cylinder hone, and its purpose is to help retain oil to allow a faster seat between the piston rings and the cylinder wall as the engine breaks in. Honing is as much an art as it is a skill. Also notice the ARP head studs we secured for the buildup. ARP is the undisputed leader in high-quality fasteners. These studs provide greater clamping force and will not stretch over time like other lesser-grade studs.
We planned to run off-the-shelf products that the average guy can find in the Summit Racing catalog because we hope to inspire readers to build engines on their own instead of spending big bucks on turnkey crate motors. For this reason, we picked a readily available forged 4340 steel crankshaft from Eagle Specialty Products. Sold through Summit Racing, Eagle crankshafts are a great value per dollar for high-performance applications. They feature non-twist forging, go through a multistage heat-treatment process, and are stressrelieved and shot-peened for longevity. Every Eagle crank is also X-rayed, Magnafluxed, and sonic tested, so you know you're getting a top-quality piece. Other noteworthy features include cross-drilled and chamfered oil holes for improved lubrication, a 0.125-inch radius on rod and main journals for increased strength, and the journals themselves are precision-ground and micro-polished and have a target bobweight of +/- 2 percent, which greatly reduces balancing time. Our crank features a 3.75-inch stroke to help achieve our 383ci displacement.