When it comes to making big horsepower numbers with the LS and LT platforms forced induction seems to get the most attention. However, most enthusiasts would likely agree there is something special about a big cubic-inch naturally aspirated engine making almost 2 horsepower per cubic inch (1.89 to be exact). Scoggin Dickey’s engine building department, known as the SDPC Raceshop, recently shared video of its latest test mule that is a beast of a power plant.
Images and video courtesy of Scoggin Dickey Parts Center
For the past ten years, the SDPC Raceshop has produced high-horsepower engine combinations known for their reliability and proven performance. Although LS engine builds are still the most popular, the Raceshop has been busy developing and testing various Gen V LT engine combinations for several years now. They have even shown the Gen V LT platform is capable of 2,000-plus horsepower by combining the L8T iron-block and forged factory crankshaft with a pair of turbochargers. As much fun as boost is, the Raceshop team changed things up for this engine build and assembled a naturally aspirated combination.
Starting with an aluminum Gen V LT block, the factory sleeves were removed to make way for longer cast-iron sleeves in preparation for the 4.125-inch stroke crankshaft. The longer sleeves offer better support of the piston at bottom-dead-center in an application such as this that has a long stroke. While they were at it, the Raceshop machinists bored the new sleeves to a 4.125-inch diameter. Filling the cylinders are Wiseco pistons made specifically for this engine project. They feature a custom dome design developed by the Raceshop team along with vertical gas ports to help push the Wiseco GFX rings against the cylinder walls for a better seal. The custom pistons result in a compression ratio of 15:1. Completing the short-block assembly are 6.125-inch long Molnar forged-steel connecting rods. This combination results in an impressive 440 cubic inches.
When trying to make a lot of naturally aspirated horsepower the cylinder heads and camshaft are vital to success. For this LT engine, a pair of Chevrolet Performance COPO Camaro cylinder heads were put to work. The COPO heads were developed by the Performance Racing Center at GM Racing and are LT1 units that have been given a proprietary CNC porting treatment. The Raceshop team assembled the COPO heads with an SDPC dual-spring kit and stock rocker arms with an upgraded CHE trunnion kit.
Actuating the valves is a custom COMP Cams hydraulic roller camshaft that features 0.644-inch of lift on the intake and 0.630-inch of lift on the exhaust with durations of 258 degrees on the intake and 273 degrees on the exhaust at 0.050-inch, and a 113-degree lobe separation angle. Although this is a Gen V LT engine, the Raceshop makes use of some LS parts on it too. Instead of the camshaft being the normal single-bolt design to be used with the LT cam phaser, this engine uses a three-bolt cam along with an LS timing chain set.
Additionally, an aluminum timing chain guide from Late Model Engines also serves to block off the factory LT oil pump port so that an external oil pump can be used. In this case, a Petersen R4 pump is driven by the crankshaft off the front of the engine. Because it no longer uses the LT1’s cam phaser there is no need for the large LT timing cover either. This timing cover is a quality piece made by Texas Speed & Performance and is designed for Gen V engines using an LS timing chain set. It relocates the Gen V cam sensor to the correct location to produce the proper 4X signal.
Sitting atop this beast is a Holley Hi Ram with a 102 mm cable-driven throttle body. Although the Gen V LT engines come from the factory with direct injection, the Raceshop team switched this engine over to port injection with a set of FID 85 lb-hr fuel injectors in the runners of the Hi Ram intake, and an SDPC plug kit was installed to fill the DI holes in the cylinder heads. The switch to port injection was made so that a Holley EFI system could be used to control the engine.
On the SDPC Raceshop engine dyno this 440 cubic-inch LT1 roars to 7,800 rpm where peak power is just over 830 horsepower and 641 lb-ft of torque at 4,100 rpm. To help achieve this level of power the engine is fed a healthy diet of VP Racing Fuels Q15 oxygenated fuel. According to the Raceshop, this engine will likely find its way into one of their COPO vehicles for further testing and development. For more information and to have the SDPC Raceshop build your next engine visit their site.