There exists a middle ground between enthusiasts who want to build their engine up from a bare block, component by component, and those who want to simply write a check (or swipe a card, these days) and drop in a ready-to-go powerplant which requires a minimum of work to get their project up and running.

In this middle-ground, the enthusiasts want to pick and install some of their own parts, but don’t want the added burden of dealing with clearances and torque specs. Chevrolet Performance already caters to both ends of the spectrum, and now with its new line of LS3-based long-blocks, has something for the “middle of the road” enthusiasts as well.

“There are a lot of aftermarket performance parts out there,” says Bill Martens, Chevrolet Performance’s associate marketing manager. “But, only a few that are designed, engineered, tested, and backed by Chevrolet. Chevrolet Performance has released a long-block replacement version of several very popular Gen-IV LS engines.”

The new line of LS3 long-blocks will feature all the same components as the crate engine versions, but without the intake manifold, fuel system, ignition system, and exhaust manifolds.

Currently, the Chevrolet Performance team has released three variants of the long-block, which correlate to complete crate engine versions of the motors.“Each long-block assembly has identical content to the matching complete engine assembly, including the camshaft,” explains Martens. Each engine is complete, minus intake manifold, throttle body, fuel rails, injectors, exhaust manifolds, ignition system, and any accessories, providing you with a blank canvas on which to build your LS3-based engine.

The three variants currently available are the standard LS3 (P/N: 19420382) based on the production LS3 engine, with L92 rectangle-port cylinder heads, the production LS3 camshaft, and is rated at 430 horsepower and 425 lb-ft of torque, using all of the factory accessories.

Next is the LS376/480 (P/N: 19420384) which is the same assembly as the standard LS3, but with the Chevrolet Performance “LS Hot Cam” installed. The camshaft ups lift to .525 inch at the valve on both the intake and exhaust side, while moving to 219 degrees of duration at .050-inch of lift on the intake side and 228 degrees of duration on the exhaust, with a 112-degree lobe separation angle.

The entire lineup of LS3 long-blocks use the awesome L92-style rectangular-port cylinder head. These heads are stout performers out of the box and will work as-is for many enthusiasts.

Then, moving to the LS376/525 (P/N 19420386) model, the cam specs have again been bumped up to make more power and spin higher, making 525 horsepower at 6,200 rpm and 486 lb-ft of torque at 5,200 rpm, with the production accessories. The even more aggressive cam’s specs come in at the same .525-inch lift at both the intake and exhaust valves, but with a more aggressive duration spec. At .050-inch lift, we have 226 degrees on the intake lobe and 236 degrees on the exhaust lobe, along with a tighter lobe separation angle of 110 degrees.

All of the long-block variants are built out of entirely new components and will work well as both a drop-in replacement for an existing LS3-powered application or as a foundation for an aftermarket project.