That's the result of a recent twin-engine marine project at Borowski Race Engines.

Actual Borowski-built marine engines photographed in our shop.

Big-block power, built for the water

High-performance marine engines have to deliver more than an impressive peak number. They face long periods of sustained load, demanding cooling and operating conditions, and a very different duty cycle from a typical street car. Our approach starts with application-focused component selection, careful machining and assembly, and engine-dyno testing before the engines head for installation.

This matching pair uses 548 cubic inches of Chevrolet big-block displacement and Whipple 3.8L supercharging, with custom blue-finished supercharger packages.

What went into these builds?

• Big-block foundation: customer-supplied Dart Big M blocks, machined and assembled by Borowski.
• Rotating assembly: Callies Compstar 4340 forged crankshafts with 4.250-inch stroke, Callies Ultra H-Beam 6.535-inch connecting rods, and JE forged flat-top pistons for a 4.530-inch bore.
• Cylinder heads: custom-assembled Dart Pro 1 aluminum BBC heads with CNC work, 2.300-inch intake / 1.880-inch exhaust valves, 360cc intake runners, and 121cc chambers.
• Valvetrain: custom-ground COMP hydraulic roller camshafts, Johnson hydraulic roller lifters and Scorpion 1.7-ratio rocker arms.
• Supercharging and fuel: Whipple marine EFI packages with 3.8L superchargers and integrated intercooling hardware.
• Preparation: complete machining, assembly and independent engine-dyno evaluation.

Two engines. Remarkably close dyno results.

Both engines were evaluated on our engine dyno on October 23, 2026. Their corrected peak output figures were:

Corrected engine-dyno peak figures; peak horsepower and peak torque occur at different engine speeds.

Engine 1: 1,169.1 horsepower at 6,500 rpm, with peak torque of 1,068.2 lb-ft.
Engine 2: 1,161.1 horsepower at 6,400 rpm, with peak torque of 1,066.5 lb-ft.

Combined, those two independently measured peak horsepower figures add up to 2,330.2 horsepower. That's an easy number to remember, but it is not a measurement of power delivered to the water: actual boat performance depends on the complete installation, drivetrain, propellers, hull, conditions and other factors.

Why dyno testing matters

Peak output makes the headline, but the shape of the power and torque curves is equally useful. Engine-dyno testing gives our team an opportunity to review performance, monitor operating data, and compare the completed engines before they are installed in a boat. With a twin-engine package, closely matched output is especially valuable.

Planning a marine engine build?

Whether you're refreshing an existing performance boat or planning a new high-horsepower package, Borowski Race Engines can help with the machining, parts selection, assembly and dyno testing. Tell us about your hull, current powertrain, drive system and intended use so we can discuss an engine combination suited to your project.

Discuss your marine engine project
Contact Borowski Race Engines  |  815-725-2727
BorowskiRace.com

Illustrative project summary. Exact specifications and dyno figures shown relate to this completed pair; future engine configurations and results will vary. Customer identity and boat-identifying information intentionally omitted.