The GM LSX engine is the quintessential expression of General Motors’ Gen IV small-block V8 architecture. Built on a tank-like cast iron block with six-bolt main caps and engineered for larger bore sizes and beefier strokes, the LSX powerplant delivers big power at all times.
This crate engine goes beyond the original small block and LS1 motor with greater durability and even higher horsepower, ideal for anything between muscle cars and high-end SUVs. Want to know what makes the LSX engine special and whether it should have a place in your business or your garage? Stick around and find out!
The LSX Engine: GM’s Gen IV Powerhouse Demystified
In its basic form, the LSX engine is a high-performance crate engine developed by General Motors (GM) as part of the broader LS engine brand. It is designed to excel in racing and high-performance applications due to a strong focus on power and durability.
As mentioned already, the LSX engine is a crate engine, which means that it is not installed in production vehicles from the factory, as it is only available as a crate engine for true enthusiasts and car builders.
LSX Engine Family Overview
The LSX engine is part of the GM engines’ Gen IV engine pack, which includes other LS engines from two generations, most notably the LS1, LS2, and LS7—all following a similar naming convention that helps identify their generation and performance tier.
What Exactly is an LSX?
What sets the X family apart is that it is designed to be a high-performance variant of the LS engine family, with features such as forged connecting rods, bellhousing bolt patterns, aluminum heads, cast iron blocks, and sodium exhaust valves.
The LSX family includes a decent range of engines, including the LSX 454, LSX 376, and LSX 427, all of which are designed for aftermarket heads.
LSX Engine Specifications: Cast Iron Power, Forged Steel Performance, and More!
- 4.065″ bore, 4.000″ stroke (454 ci)
- 437-776 hp, 444-680 lb-ft
- 10.7:1 compression, 6-bolt mains
- Hydraulic roller camshaft
From a structural perspective, the motor utilizes a 4.065-inch bore size and a 4.000-inch stroke, which is good for a displacement of 454 cubic inches.
With this larger bore size and considerably longer stroke, it allows for higher combustion volumes and higher horsepower potential compared to older LS engines. With a cast iron block and 6-bolt bearing caps, the LSX ensures strength and durability, which makes it perfect for high-performance builds.
How Much Power Does the LSX Make?
On premium gasoline, the engine pushes out up to a formidable 776 horsepower and680 lbft of torque, delivering the level of grunt and horsepower that muscle car lovers and engine swap builders look for. It is a true enthusiast’s delight as these impressive figures come from forged steel connecting rods and titanium valves designed to withstand serious levels of abuse.
It also features a 10.7:1 compression, which further balances horsepower output with reliability, while the 1.7:1 rocker arm ratio improves valve lift for better airflow. Add a hydraulic roller camshaft paired with variable valve timing, you are looking at an engine even the mighty LS series can’t touch.
What are the Essential Parts Powering the LSX Motor?
Even though the specs are indeed impressive, what’s even more remarkable is how these Gen IV engines expertly blend high-end materials like aluminum, cast iron, and forged steel into pure automotive bliss.
Here is what you need to know:
| Parts | Description |
|---|---|
| Engine Block | Cast iron block with 6-bolt bearing caps for superior strength and durability. |
| Valvetrain | Titanium intake valves + sodium exhaust valves for heat resistance and reliability. |
| Internals | Forged crankshaft and steel connecting rods are built for high push and horsepower. |
| Camshaft & Fuel System | A hydraulic roller camshaft paired with active fuel management for optimum efficiency and performance. |
LSX Engine Key Features at a Glance
- 6-Bolt Bearing Caps: Great block rigidity designed to handle high horsepower builds.
- Titanium Intake Valves: Lightweight, durable, and designed to withstand extreme engine wear.
- Sodium-Filled Exhaust Valves: Balanced heat dissipation reduces valve wear during high RPM use.
- Steel Crankshaft & Rods: Ensures maximum strength and reliability under severe load.
- Hydraulic Roller Camshaft: Eases off friction and improves valve timing precision across the range.
- Active Fuel Management: Dynamically optimizes fuel usage for a balance between power output and efficiency when most needed.
What are the Best Performance and Upgrades for the LSX?
There are various performance and upgrade options available for small-block LSX crate engines, but the most popular ones are designed to maximize both power and durability.
As such, the engine can be upgraded with a range of upgrades, including cylinder heads, camshafts, and intake manifolds (to name a few). Some people also modify active fuel management systems, while track-ready enthusiasts even do aluminum blocks for weight savings and better balance.
Cast pistons, bore spacing, hollow stem valves, forged titanium parts, and rectangular ports can all make major differences, which can make the LS series of engines seem slow. All in all, the LSX is an immensely tunable engine.
Is the LSX Emissions Legal?
It’s also worth mentioning that the engine is legal in some states, but may require additional modifications to meet emissions standards in others. The best thing would be to check your local DMV and ask for further information.
LSX Crate Engine: Contents and Compatible Vehicles
The X motor is available as a crate engine directly from Chevy Performance, and it tends to include a range of parts, including the engine block, cylinder heads, and intake manifold.
The engine can be installed in a range of vehicles, including muscle cars, trucks, SUVs, and even track-ready sports vehicles. Some people will even do sleeper builds and make their GMC Yukon Denali and GMC Sierra family SUVs way more fun to drive compared to using LS engines.
All in all, not many GM engines are as exciting as the LSX series, and the sky is truly the limit when it comes to what you can do with it.
How to Install an LSX Motor? – Step-by-Step Installation Guide
Now that you know what this motor is capable of, it’s time to consider installing one of these in your beater of choice. Here’s a list of the essential tools you absolutely need to install an LSX powerplant!
- Engine hoist or crane
- Torque wrench (for proper bolt tightening)
- Socket and wrench set (various sizes)
- Engine mount brackets and bolts
- Transmission jack (if removing or installing the transmission)
- Fuel line disconnect tool
- Wiring harness tools (wire strippers, crimpers)
- Funnel (for adding fluids)
No matter if you own a business, repair shop, or just are an average Joe with a car problem, these are the must-haves—without them, the installation would be unsafe or impossible, so keep that in mind.
Prepare Your Engine Bay – Bore x Stroke
Before installing your next small-block V8, make sure your engine bay is clean and free of old bits that might get in the way. Having enough space to work with is non-negotiable.
Because the LSX is part of the Gen IV small block family, understanding bore x stroke spacing and engine mount placement is critical for a smooth install and perfect compatibility, so do your research!
Gather the Right Parts
Make sure you have all necessary parts, as the crate engine by itself can often require additional modifications depending on the engine you are swapping it with.
For example, make sure to check the transmission adapter (if needed), new gaskets, and quality engine oil because the LSX’s 6-bolt main bearing caps and forged upgrades are hallmarks of the LS family’s commitment to high-end performance.
Mount the LSX Engine
An engine hoist is an absolute must-have! Once properly hooked up, carefully position the LSX motor into the bay.
Thanks to the Gen IV small block architecture and consistent LS designation, the LSX shares the bellhousing bolt pattern with many Gen III LS engines, which will make some swaps a lot easier.
Be sure to properly align the mounts and secure all the bolts, double-check every connection, check the transmission height, and inspect everything once more.
Connect the Wiring and Fuel Systems
With its impressive active fuel management and variable valve timing, the LSX evolved from earlier LS family engines into quite a techfest. Even though this does modernize the engine, it also makes it more difficult to successfully swap it.
This means that you’ll have to properly reconnect the harness and fuel hoses using the manufacturer’s service guides. Proper sensor hookups are also key for harnessing the full potential of these LS engines and achieving more power and efficiency without experiencing issues down the line.
Fill Fluids and Check Systems
Once you’ve successfully hooked up your new small-block V8, it’s time to add fresh engine oil and coolant per the appropriate LSX engine’s specifications.
With its forged crankshaft and hydraulic roller camshaft, proper lubrication is crucial to maintain longevity and push more power than any Gen III could ever dream of.
Test and Tune Compression Ratio
Start the engine and monitor for leaks or any unusual noises, especially on a cold start. The X’s advanced components and active fuel management respond well to tuning, but only if all of the hardware has been successfully dialed in.
No matter if you’re upgrading from Gen III or another LS family member, a professional tune will give you more power and grunt for your specific needs, fully leveraging the benefits of the LS designation!
Does Chevrolet Performance Make the LSX?
As with the Gen III, the Gen IV engine has also been developed in partnership with Chevy’s Performance subdivision, the birthplace of performance within the General Motors umbrella.
Chevy Performance offers a range of components and accessories for the LSX engine, including cylinder heads, camshafts, and intake manifolds, all of which have been made to the highest of standards with best-in-class compatibility.
Chevy Performance offers support and quite a solid warranty coverage for the LSX engine, including a 3-year or 36,000-mile limited warranty—similar to what they provide for other high-end small block LS engine series.
What does the LSX Engine Warranty and Support Include?
The aforementioned LSX engine comes warranty from Chevy Performance, covering defects in materials and workmanship, as is often the case with such engines.
However, it’s worth mentioning that Chevy isn’t likely to cover expenses tied to shady installation or lack of proper maintenance. Even though they do offer technical support with installation guides and troubleshooting services, you’ll still have to do your best to schedule maintenance chores.
With proper care and proper installation, these LS engines are designed to be durable and reliable, no matter what you use them for.
Wrapping Up: Why the LSX Engine Stands Out
In a world of LS engines, big power is almost always guaranteed, but few LS engines can actually give you the experience akin to the mighty crate LSX.
You can’t get these in your normal aluminum blocks Chevy Impalas and even high-performance offerings, as these big horsepower motors are only available as crate upgrades.
Compared to previous small blocks, the LSX is a significant step forward in durability and performance, but it does require scheduled maintenance just like any other.
So, if you or your business wants to reach big power with that iconic muscle V8 firing order, the LSX casting number under your hood is indeed a perfect choice.
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