Watch and listen as a Mast Motorsports-built LSX 440 Black Label engine with a customer-specified camshaft and Mast Motorsports single-plane LS7 4500-flange intake manifold makes more than 700 horsepower!

This particular build displaces a whopping 7.2 liters, or 440 cubic inches. The Mast X-block was bored to 4.185-inch, and supports a Callies forged 4.000-inch stroke crankshaft and Callies forged connecting rods. The 12.0:1 compression ratio is achieved through the use of forged Diamond Racing pistons, and the final dyno numbers are an impressive 707.9 horsepower and 597.8 lb-ft of peak torque.

The star of the show in this build is without a doubt the Mast Black Label CNC-ported LS7 305cc cylinder head. These heads use the Gen IV LS7 valvetrain and intake manifold architecture and are designed to fit on any short-block with a 4.125-inch or larger bore.

Intake valves spec out at a whopping 2.250-inch and are angled at 12 degrees for improved airflow, while the exhaust valves check in at 1.600-inch. Flow numbers on these castings exceed 300 CFM from .400-inch lift and 400 CFM from .800-inch lift on up, while exhaust flow at 1.000-inch of lift tops out at 263 CFM on a 4.125-inch bore – which extrapolates to even more flow on the larger bore this engine uses.

“Our heads and intake work extremely well together. The engine we used in this build was a hydraulic roller camshaft, and when used with a solid-roller camshaft with more aggressive timing events, the induction package is good for well over 800 horsepower,” Mast’s Chris Durrett tells EngineLabs.

Mast’s LS7 4500 single-plane EFI manifold was the top choice to ensure enough airflow into the engine. The two-piece manifold is designed using the latest in computer software and arrives fully ported and hand-blended for maximized intake port velocity and airflow. 

“We used a Wilson 4500-series throttle body on top – that thing is a beautiful piece and it’s the first one we’ve ever used. It worked out really, really well for us here. The engine also has a Holley HP EFI system, along with Injector Dynamics fuel injectors. The Holley system tunes very easily,” says Durrett.

The LSX engine platform has proven to be very versatile – it’s relatively rare to see one in a naturally-aspirated application, and the Mast Motorsports team is at the front of LSX engine development – as proven here.