The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →GM’s LS3 is a Gen IV, 6.2-liter (376-cubic-inch) aluminum small-block V8 best known for its factory-rated 430 horsepower. The current Chevrolet Performance crate specification lists 430 hp at 5,900 rpm and 425 lb-ft at 4,600 rpm; the 2008 Corvette production calibration was rated at 430 hp and 424 lb-ft. Its rectangular-port heads, compact dimensions, strong bottom end and available crate-engine support make it a popular street, restoration and swap choice—but the electronics and break-in procedure are part of the job.
1. It is a 6.2-liter Gen IV LS engine
Chevrolet Performance identifies the current LS3 crate engine as a Gen IV small-block V8 displacing 376 cubic inches, or 6.2 liters. The current crate part number is 19540155. “LS” identifies the engine family; LS3 is the specific 6.2-liter combination rather than a generic name for every LS engine.
As an Amazon Associate I earn from qualifying purchases.
| Specification | LS3 value |
|---|---|
| Architecture | Gen IV small-block V8 |
| Displacement | 6.2 L (376 cu in) |
| Current crate part | 19540155 |
| Maximum recommended speed | 6,600 rpm |
2. Horsepower depends on which LS3 calibration you mean
For the current Chevrolet Performance crate specification, the answer to “How much horsepower does an LS3 make?” is 430 hp at 5,900 rpm and 425 lb-ft at 4,600 rpm. GM Powertrain’s 2008 Corvette summary lists the production engine at 430 hp and 424 lb-ft at the same torque peak speed. The one-pound-foot difference is a calibration and documentation distinction, not a different displacement.
Recommended Free Tools
| Application | Power rating | Torque rating | Source context |
|---|---|---|---|
| 2008 Corvette production LS3 | 430 hp at 5,900 rpm | 424 lb-ft at 4,600 rpm | GM Powertrain historical summary |
| Current LS3 crate specification | 430 hp at 5,900 rpm | 425 lb-ft at 4,600 rpm | Chevrolet Performance product specification |
Use the crate rating when planning a new crate installation and the Corvette rating when documenting an original production car.
#1 Best Overall
- GM PERFORMANCE PARTS 19301326 Crate Engine - 6.2L LS3 430HP
- Dimensions in Inches (LxWxH): 42 x 42 x 31
3. Its bore, stroke and compression create the displacement
The LS3 reaches 6.2 liters with a 4.065-inch bore and 3.622-inch stroke. Its listed compression ratio is 10.7:1. The large bore supports the engine’s large rectangular intake ports and valve package, while the relatively shorter stroke is part of the combination’s ability to operate to the specified 6,600-rpm limit.
4. The aluminum block is light but heavily supported
The block is cast aluminum, reducing mass compared with an iron block, and uses six-bolt, cross-bolted main caps. Those additional cross bolts tie the main-cap structure into the sides of the block, an important part of the LS3’s bottom-end design for a high-output production V8.
Rank #2
- GM Parts Engines 5.7L Gen I
- Legal for sale and use in California
- These are 2-bolt mains with one-piece rear seal
- Not designed, nor intended to be used in any marine applications
- 350 cubic inch
5. The L92-style heads are a major airflow feature
LS3 cylinder heads are aluminum L92-style units with rectangular intake ports. They use 68cc combustion chambers, 2.165-inch intake valves and 1.590-inch exhaust valves. This head and port arrangement is one of the clearest differences between an LS3 and smaller-displacement LS combinations: the ports and valves are sized to move substantially more air than the earlier LS2 package.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
6. It uses a hydraulic roller valvetrain
The factory-listed camshaft and rocker specifications are:
- Valve lift: .551 inch intake and .522 inch exhaust
- Duration at .050 inch: 204 degrees intake and 211 degrees exhaust
- Rocker ratio: 1.7:1
- Valve-lifter type: hydraulic roller
That combination is intended to provide a streetable operating range while taking advantage of the LS3 heads’ airflow. Changing the cam, intake or cylinder heads changes the engine’s powerband and may require matching calibration and supporting parts.
7. The LS3 replaced the LS2 in the 2008 Corvette
GM Powertrain’s historical summary identifies the LS3 as the replacement for the Corvette’s 6.0-liter LS2 beginning with the 2008 model year. The upgrade was not just a displacement increase: GM cited the larger bore, higher-flow cylinder heads and intake, revised fuel injectors and valvetrain changes.
Rank #4
- Crate Motor Shoot-Out
| Comparison point | LS2-to-LS3 change described by GM |
|---|---|
| Displacement | LS3 increased from the LS2’s 6.0-liter size to 6.2 liters |
| Bore and airflow | Larger bore plus higher-flow heads and intake |
| Fuel system | Revised injectors |
| Valvetrain | Valvetrain changes were included in the new combination |
For a restoration, verify whether the goal is an original LS2 specification or an LS3-era replacement; the engines are not interchangeable in specification merely because both carry the LS family name.
8. A crate LS3 is not a plug-and-play engine by itself
Chevrolet Performance states that LS3 crate engines require an engine-control system and harness. Budget for those pieces with the engine rather than treating the long block as the entire swap.
Best Value
- PREVENT DRY STARTS – Prime the oiling system before initial startup, engine rebuilds, cam swaps, lifter replacements, oil pump replacement, or long-term storage recovery.
- FITS ALL GM LS ENGINES – Compatible with LS1, LS2, LS3, LS6, LS7, LSX, 4.8L, 5.3L, 5.7L, 6.0L and 6.2L Chevrolet and GM V8 engines.
- PROFESSIONAL ENGINE BUILD TOOL – Allows oil to reach bearings, lifters, rocker arms and valvetrain components before engine startup.
- COMPLETE KIT INCLUDED – Includes M16x1.5 adapter fitting, hose barb fitting, sealing washer and hose clamp for quick installation.
- IDEAL FOR LS SWAPS & REBUILDS – Essential tool for LS engine swaps, crate engine installations, performance builds, race engines and restoration projects.
LS3 swap electronics checklist
- Engine-control system compatible with the specific LS3 crate calibration
- Matching engine wiring harness
- Compatible sensors, throttle and fuel-system connections for the chosen installation
- A plan for integrating the engine controls with the vehicle’s starting, charging and instrumentation circuits
Before ordering, confirm connector compatibility, transmission and vehicle integration requirements, and whether the seller is supplying a complete engine or a long block. The exact ECU and harness combination depends on the vehicle and installation package; the crate-engine requirement itself is universal.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.9. Choose the engine package by the job, not just the 430-hp headline
The 430-hp LS3 is the baseline specification. Chevrolet Performance also identifies modified LS376 variants, but a variant’s exact output and included hardware must be taken from its own current product specification rather than assumed from the standard LS3 rating.
Complete crate engine versus long block
Listings use these terms differently, so read the included-parts list. A complete crate engine may be sold as a more installation-ready package, while a long block generally requires the buyer to transfer or purchase additional external components. Confirm the following before comparing prices:
- Whether intake, throttle body, fuel rails, injectors, ignition components and accessory drive are included
- Which oil pan and mount arrangement the package uses
- Whether the engine-control system and harness are included or separate
- Warranty terms, calibration compatibility and the exact part number
Match the package to the use
- Street or restoration: prioritize the documented calibration, emissions and vehicle-integration requirements.
- Swap: plan the control system, harness, mounts, oil pan, cooling and transmission interface before buying.
- Competition: compare the particular LS376 or other modified specification, its intended rpm range and the rules for the class; do not substitute the standard LS3 rating.
10. Break-in is an installation requirement
For a new LS3 crate engine, Chevrolet Performance’s guidance calls for 500 miles or 12–15 engine hours under normal conditions. During that period:
- Run the engine under normal, varying conditions rather than holding one speed for long periods.
- Avoid maximum rpm and prolonged high-load operation.
- At the end of the break-in interval, change the engine oil and filter.
- Inspect the drained oil and filter for abnormal particles before returning the engine to normal service.
The 6,600-rpm figure is the specified maximum recommended speed, not a target for break-in. Complete the initial checks, resolve leaks or warning lights immediately, and follow the installation guide for the exact oil and service procedure supplied with your engine.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
