*Engine Shown With Optional Upgrades

Sale!

LS3 427CI Short Block

Original price was: $7,995.00.Current price is: $7,495.00.

Take the guesswork out of your next high-horsepower build with the Proformance Unlimited 427 CI GM LS Compatible Short Block. Engineered specifically for the DIY home mechanic, this fully machined and internally balanced foundation saves you the hassle of building a bottom end from scratch. Capable of supporting up to 700HP, it comes fully loaded with our new PFU A356 aluminum block, a 4340 forged rotating assembly, and Mahle forged pistons—ready for you to bolt on your top-end components and finish the job.

Engine Build Specifications:

Build Your Dream LS Without the Machine Shop Hassle

For the do-it-yourself home mechanic, assembling an engine is a highly rewarding experience—but dealing with the meticulous tolerances, clearancing, and balancing of a short block can be a frustrating roadblock. Proformance Unlimited has the perfect solution. Our 427 Cubic Inch GM LS Compatible Short Block gives you a rock-solid, expertly assembled foundation ready for your choice of heads, cam, and intake. We’ve handled the exacting precision work so you can focus on the fun part: finishing the build and getting your vehicle on the road.

Designed to reliably support up to 700 horsepower, this combination is anchored by our all-new PFU Performance A356 Aluminum Block, which features heavy-duty billet main caps and MLS-ready decks. Inside, we pack it with a premium, fully forged rotating assembly built to handle serious abuse. Whether you’re building a pro-touring street machine, a classic restomod, or a track weekend warrior, this short block delivers the displacement and durability you need.

Short Block Specifications & Components:

Engine Block: New PFU Performance GM LS 6.2L Compatible A356 Aluminum Block (Features a 4.065″ bore, Billet Main Caps, straight-through cam tunnel, and MLS-ready decks)
Crankshaft: 4340 Forged 4.125″ stroke LS crankshaft (equipped with a 58x reluctor wheel)
Connecting Rods: 4340 Forged 6.125″ length I-Beam connecting rods fitted with high-strength ARP cap screws
Pistons: Mahle 2618 Forged Aluminum Pistons (11.0:1 with 72cc chamber)
Bearings: High-performance rod and main bearings (Clevite or King)
Balancing: Complete internal assembly balance performed by our expert engine builders
Take control of your custom engine project. Start with a proven, bulletproof bottom end from Proformance Unlimited, and build the 415 CI LS powerhouse you’ve always wanted.

** Due to variables outside our control—including final assembly and engine tuning—this short block does not carry a warranty. (Current build time is 6-8 Weeks)**