BluePrint Builder Series LS427/625HP Standard Edition EFI Crate Engine and 4L65/70E Trans Combos BLS427K4L7

BluePrint steps up to a 625-horsepower, 427 cubic-inch LS combo here, paired with a 4L65/70E automatic and a polished front accessory drive. It is built with forged pistons and a forged crankshaft, producing 565 lb-ft of torque from an 11.0:1 compression ratio.

Who this suits

This is aimed at a swap builder who wants more displacement and output than BluePrint's smaller LS small-block combos while staying with an LS-based control system and an automatic transmission. The long block ships with an unlocked ECU for local dyno tuning, an LT4-style 87mm drive-by-wire throttle body, a stock-style LS3 intake manifold, and 42-pound injectors feeding from a return-less fuel rail.

What to check before ordering

The 427 is sized to Chevrolet's 7.0L/427 LS engines, built from 2006 through 2015, so confirm your vehicle or chassis falls in that window. A retro-fit oil pan sized for most 1955-95 GM front-engine, rear-drive V8 cars comes with the kit, which matters if you are swapping this into an older body. BluePrint does not recommend this combination for dry-sump oiling or pollution-controlled vehicles, and specifies 91-93 octane fuel with its own BPP710 oil, and points buyers toward its matching air intake kit to keep the mass air flow reading on target.

Common questions

Is the ECU locked to factory settings? No, BluePrint ships it unlocked so a local dyno shop can refine the tune.

Do I still need to buy a flywheel? No — the 4L65/70E automatic uses the flexplate that comes in the box.

What transmission controller comes with it? The 4L65/70E's own electronic unit; the converter is tuned for a 2,200-2,400 rpm stall.