Hardcore Horsepower’s 692 HP 406ci Chevy
A 406 cubic inch small block is one of the most popular choices for Chevy powered sportsman drag racers seeking strong reliable power at reasonable cost. Careful planning and the right mix of parts can push the power close to 700 HP without exotic or costly components. Variations include the option to take the motor to 415ci, 421ci or even 434 cubic inches if so desired. Still, a lot of racers seem to favor the 406 even though it’s not a great deal more expensive to build the larger versions.
People claim that they can build these engines for as little as 5-grand and likely they can with second-hand parts and already owning a few parts like a block and an intake and such. That’s all well and good if you don’t care about durability and you’re willing to risk the consequences. We can’t call this a budget engine, but it’s pretty reasonable for the amount of power and long term durability it delivers.
Hardcore Horsepower owner Mike Petralia has been a proponent of 400-Chevy based small block motors for a long time; and why not? The larger bore encourages superior breathing with today’s high flowing heads and you can get them with either 350 or 400 mains depending on how solid you want to make the lower end. Mike campaigned a 406ci ’82 Camaro in the highly competitive PSCA 10.60 index class for several years so he knows the best combination of parts for max power and longevity.
Based on his extensive experience Hardcore Horsepower paves the road to strong reliable power with a compatible mix of parts chosen to narrow the gap between affordable cost and big power. In the final analysis, this particular engine delivered 692 HP and 559 lb-ft of torque. While not a rock bottom low-buck creation, it’s not a mega-dollar over-the-top LSX combination either. It's genuine first generation small block with power and durability to spare.
One of Hardcore Horsepower’s customers commissioned this brawny first generation small block for a ’94 Camaro with an automatic transmission. With the right car setup its capable of dipping into the nine second bracket while providing the durability to race a season or two without loss of performance. When planning these engines, Mike stresses fundamentals and preparation. With the right selection of parts and meticulous preparation he knows from experience that these engines will make big power and stay together. He likes these engines and is a firm believer that any good first generation small block is easily the equal or better than currently popular LS series engines that are typically more expensive to build.
Above: The foundation for this power player is a fully prepped Dart “Little-M” cylinder block which comes with all the important performance enhancements like 4-bolt steel main caps with premium ARP fasteners and priority main oiling passages. Mike performs all the standard prep operations like squaring the cylinder block and torque plate honing the 4.155-inch bores for proper skirt clearance with the JE forged pistons.Rock solid Scat crankshaft and connecting rods form the foundation for this high horsepower build. Careful parts preparation and meticulous checking and rechecking ensure a trouble free setup. Mike says the quench height was set at a modest .045 -inch and the piston to valve clearance was .120-inch on the intake valve and it never even touched the clay on the exhaust valve.
Above: Power starts with a set of 215cc Dart aluminum heads that have been CNC ported and opened up to 230cc by High Velocity Heads (HVH) in Knoxville, TN. The heads are angled milled to achieve 60cc chambers which deliver 14:1 compression with the JE domed pistons. They are outfitted with 2.08-inch intake and 1.60-inch REV stainless steel valves for good durability. The valves are anchored with 650-lb springs (open) and Ti retainers. The cam is a custom Comp Cams mechanical roller, steel billet core ground with the 4/7 swap.
Above: An SBC dual-idler gear drive was used to provide precise cam timing and high durability. On a similar note, durability and big power call for checking and double checking every component for possible conflicts. Mike discovered that the inner face of the Yella Terra aluminum rockers was contacting the spring retainers. He cured it by spot cutting the rockers in the Bridgeport. The Edelbrock Super Victor intake was ported and matched by High Velocity Heads and topped with a 2-inch HVH spacer and a 950 CFM Holley carburetor with drag race calibration.
Mike Petralia's Hardcore Horsepower