Summit Racing™5.3 L 450HP Chevy LS Motor Is The Ultimate Crate Engine
Looking for significant power on a budget? We review the Summit Racing Chevy LS 5.3L 450HP crate engine and why it's the ultimate swap.
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Building a high-performance engine is often a battle between your budget and your horsepower goals. For years, car enthusiasts have had to choose between rolling the dice on a high-mileage junkyard motor or emptying their savings account for a custom-built race engine. There hasn't been much middle ground for the mechanic who wants reliable, serious power without the exorbitant price tag and months of waiting on a machine shop.
Enter the Summit Racing™ Chevy LS 5.3L 450HP Long Block Crate Engine (Part Number SUM-150153). This isn't just a stock replacement; it is one of Summit Racing's popular crate engines, with an actual displacement of 5.3L (323 cubic inches).
It is a meticulously remanufactured power plant designed to bridge the gap between affordability and high-end performance. By combining a seasoned GM block with free-flowing aluminum heads and a perfectly matched cam, Summit Racing has created a solution that drops right in and wakes up your ride immediately.
Whether you are breathing new life into a tired 1999-2007 Chevy truck or hunting for the perfect heart for your next muscle car restomod, this engine ticks every box. The engine is remanufactured and comes with a 2-year unlimited-mile warranty, giving buyers peace of mind. It offers the legendary reliability of the LS platform with a massive bump in output that you can actually feel in the seat of your pants.
In this guide, we are going to tear down the specs, analyze the components, and explain precisely why this 5.3L long block might be the best "bang for your buck" crate engine on the market today.
Summit Racing™ Chevy LS 5.3L 450HP Long Block Crate Engine
Summit Racing™ remanufactured 5.3L LS long-block crate engines are rated at 450 HP and 420 lb-ft. Torque
Overview: What is the Summit Racing™ SUM-150153?
At its core, the SUM-150153 is a Gen III GM LS-series engine. However, calling it "stock" would be a massive understatement. Summit Racing has partnered with the engine-building experts at ATK to optimize the ubiquitous 5.3L platform for street performance.
The concept is simple: take the most robust factory components, pair them with modern aftermarket upgrades, and assemble them with professional precision. The result is a "long block" crate engine. For the uninitiated, a long block includes the engine block, rotating assembly (crank, rods, pistons), camshaft, and cylinder heads. It arrives assembled and timed, leaving you to bolt on your intake, exhaust, and accessories simply.
This approach eliminates the two biggest hurdles in engine building: the need for specialized machining tools and the risk of assembly errors. You aren't measuring bearing clearances in your dusty garage; you're uncrating a professionally built motor that is ready to run.
The Numbers Game: 450 Horsepower and 420 Torque
Let's talk about the figures that matter most. This engine is rated at 450+ horsepower and 420+ ft.-lbs. of torque. To put that in perspective, a stock 5.3L LM7 engine from the early 2000s typically produced around 285 to 295 horsepower. In fact, dyno test results show that a 5.3L LS engine can produce around 350 hp in stock trim, highlighting the significant performance difference achieved with these upgrades.
We are talking about a 50% increase in power over the stock configuration.
What does 450HP feel like?
In a full-size Silverado or Sierra, 450 horsepower transforms the truck from a sluggish hauler into a genuine sleeper. Merging onto highways becomes effortless, and towing capability is significantly bolstered by the increased torque curve.
If you are dropping this into a lighter project car, like a Camaro, Nova, or Fox-body Mustang, 450 horsepower provides thrilling acceleration. The engine's ability to rev quickly through the RPM range adds to the excitement, delivering a responsive and engaging driving experience.
It's enough power to break the tires loose on command, yet manageable enough for daily driving. The torque figure of 420 lbs.-ft. It is equally important; it ensures that the engine doesn't feel "lazy" at low RPMs, providing that instant grunt that V8 owners crave.
Technical Deep Dive: What's Inside?
To understand how Summit Racing achieves these numbers while keeping the price tag at $3,849.99, we need to look at the specific recipe of parts they've used. The work involved in assembling and upgrading a 5.3L LS engine, such as camshaft and head work, intake swaps, and tuning, plays a crucial role in boosting horsepower and torque. Summit Racing offers extensive aftermarket support for the 5.3L truck engine, including camshafts, cylinder heads, and forced induction options, making it easier for enthusiasts to achieve their performance goals.
The Foundation: Seasoned OE LM7 Block
The build starts with a seasoned OE LM7 5.3L iron block. You might wonder, "Why not a new block?" In the world of performance, a "seasoned" block is actually desirable. These blocks have been through thousands of heat cycles, which relieves internal casting stresses.
This makes them incredibly stable and less prone to shifting or cracking under high load compared to a "green" (brand new) casting. The Summit Racing 5.3L crate engine features a cast-iron engine block and aluminum cylinder heads.
The block is bored to 3.800-3.820 inches and decked to ensure a perfect sealing surface for the head gaskets. For added durability, the block comes with brass-installed freeze plugs. The engine's internal components are carefully balanced (engine balance) for smooth operation and longevity.
Specific components have been changed or upgraded from the original OEM versions to improve performance. Critical components, such as camshaft bearings, are clocked during assembly to ensure proper alignment and function.
The Cylinder Heads: Aluminum #799 or #243
This is where the magic happens. The engine comes equipped with OE aluminum cylinder heads, specifically casting numbers #799 or #243. Enthusiasts know these as the "LS6 style" heads. They feature 64cc combustion chambers and 2.00-inch intake/1.55-inch exhaust valves.
These heads flow significantly better than the standard truck heads found on older 5.3L engines. The improved airflow is the primary reason this engine can support 450 horsepower naturally aspirated. The added benefits of upgraded heads include increased power and efficiency, especially when combined with other performance upgrades.
Summit Racing provides various performance upgrades for 5.3-liter engines, including internal components and external parts such as headers and intake manifolds, to further enhance the engine's capabilities. By using factory castings rather than expensive aftermarket heads, Summit keeps the cost down without sacrificing the necessary airflow.
The Camshaft: The Heart of the Beast
You can have great heads and a solid block, but without the right camshaft, the engine won't perform. This crate engine utilizes a Summit Racing Pro LS Roller Camshaft.
- Lift: .550 in. Intake / .550 in. Exhaust
- Duration: 222° Intake / 232° Exhaust (@ .050 in.)
- Lobe Separation: Engineered for a balance of power and idle quality.
This cam profile is aggressive enough to produce a noticeable, choppy idle (that muscle car sound we all love) and strong top-end power. However, with a .550 lift, it isn't so aggressive that it destroys valve springs or makes the vehicle a nightmare to drive in traffic. It hits the "Goldilocks" zone of performance and drivability.
The Rotating Assembly
Inside the block, you'll find a robust bottom end designed to handle the increased output:
- Crankshaft: OEM GM 3.622 in. stroke, internally balanced with a 24-tooth reluctor wheel.
- Connecting Rods: OE GM forged powder metal 6.093 in.
- Pistons: Hypereutectic flat top pistons with Moly rings.
- Rear Main Seal: 1-piece rear main seal for improved reliability and ease of installation.
The one-piece rear main seal is crucial for preventing oil leaks and ensuring long-term durability of the engine.
The compression ratio sits at a healthy 10:1. This is high enough to maximize thermal efficiency and power but low enough that you can still comfortably run pump gas without constant fear of detonation.
Who is this Engine For?
The versatility of the LS platform is legendary, and this specific crate engine caters to two distinct groups of automotive enthusiasts. The Summit Racing 5.3L crate engine is designed for use in 1999-2007 Chevy trucks and is also ideal for LS swap projects, making it a great choice for a wide range of LS swap applications.
1. The Truck Enthusiast (1999-2007 GM Trucks)
If you own a Chevy Silverado, Tahoe, Suburban, or GMC Sierra from the "GMT800" era, your truck likely has a tired high-mileage 4.8L or 5.3L engine. The original engine can be easily replaced with the Summit Racing 5.3L crate engine for a significant performance upgrade. This crate engine is the ultimate replacement. Because it is based on the Gen III architecture with a 24x reluctor wheel, it is largely a bolt-in affair for these trucks. You get a fresh engine and a massive performance upgrade in one weekend.
2. The Restomod Builder (LS Swaps)
For those building a classic car, the 5.3L offers the best value in the LS ecosystem. Crate engines, like the Summit Racing 5.3, provide a convenient and cost-effective solution for restomod and swap projects, as they come pre-assembled and ready for installation.
While the 6.0L and 6.2L engines are popular, they command a massive price premium. This 5.3L, with its upgraded cam and heads, produces power figures that rival stock 6.0L engines but at a fraction of the cost. It's the perfect candidate for swapping into C10 pickups, G-body cutlasses, or even classic imports.
Installation Tips and Critical Considerations
While this is a "drop-in" crate engine, achieving the advertised 450HP and ensuring longevity requires paying attention to a few details during installation.
- The engine comes with a timing cover and other essential covers, such as the front cover and valve covers, pre-installed for convenience and protection.
- Harmonic balancer included: The harmonic balancer is included with the engine, so you won't need to source this critical component separately.
1. Tuning is Mandatory
You cannot run this engine on a stock ECU tune. The camshaft duration and increased airflow will confuse a stock computer, leading to poor idling and potential engine damage. You will need a custom dyno tune or a reputable mail-order tune to unlock the full potential and ensure safe air/fuel ratios.
Tip: ECU tuning is required for optimal performance after making upgrades.
2. Injector Upgrades
The stock injectors from a 1999-2002 truck (usually around 25 lbs./hr.) are likely too small to support 450 horsepower. Summit Racing recommends upgrading to at least 36 lbs./hr. Fuel injectors to ensure the engine doesn't lean out at high RPM.
3. Oil Pan and Pickup
The engine ships with a 1999-2007 Chevy Truck LM7 oil pump pickup tube installed. If you are putting this in a truck, you are good to go. However, if you are swapping this into a car and using a different oil pan (like a low-profile Holley pan), you must change the pickup tube to match your specific oil pan. Failing to do this will starve the engine of oil.
4. Valve Covers
The product notes specifically warn against reusing valve covers with plastic baffles, as old debris can dislodge and damage the engine. Invest in a clean set of valve covers or ensure your metal-baffled ones are spotless.
5. Plugs
Be sure to use the correct plugs, including spark plugs and any required sealing plugs, during installation to ensure proper engine performance and compatibility.
6. Throttle Body Upgrade
Consider upgrading the throttle body to improve airflow and boost horsepower and torque, especially if you are aiming for high-performance results.
7. Forced Induction Support
The 5.3L engine can support forced induction setups like superchargers or turbos with proper tuning and supporting modifications.
8. Additional Performance Upgrades
Performance can be further enhanced with aftermarket upgrades such as headers and a high-performance intake manifold.
Why Choose Crate Over Junkyard?
The "junkyard LS" is a popular internet trope. "Just grab a 5.3 from a van for $500 and slap a turbo on it!" While that works for some, it's a gamble. You don't know the maintenance history, you have to pull it yourself, and you have to clean years of sludge.
With the Summit Racing SUM-150153, you are paying for peace of mind.
- Warranty: It is backed by a 2-year, unlimited-mile warranty. Good luck getting that from a salvage yard.
- Convenience: It arrives clean, machined, and assembled.
- Reliability: New bearings, rings, seals, and oil pump mean you won't be pulling the engine back out in six months because of a spun bearing.
Specifications:
- Make: CHEVROLET
- Engine Type: V8
- Engine Size: 5.3L/325
- Engine Family: CHEVY SMALL BLOCK GEN III/IV LS V8 GAS
- Cylinder Head Type: Stock configuration
- Fuel Type: GAS
Application Notes: Exhaust and injector upgrades are recommended for optimal performance. ECU tuning is required. This engine includes a 1999-2007 Chevy Truck LM7 oil pump tube. If an aftermarket or different OEM oil pan is used, the appropriate oil pump tube must be changed to match the pan. Do not reuse valve covers with plastic baffles; there may be leftover debris that could damage the engine. Not intended for marine use.
Customer Sentiment: What are People Saying?
With a rating of 4.25 out of 5 stars from over 40 reviews, the community consensus is strong. Customers frequently praise the noticeable power gains over stock. Many reviewers highlight that the "chop" from the cam sounds aggressive, but cleans up nicely with a proper tune.
The critique usually centers on the need for supporting mods (tuning, injectors, torque converter), which is standard for any performance engine build. The value proposition, getting 450HP for under $4,000, remains the consistent theme in positive feedback.
Shipping and Availability
One of the distinct advantages of ordering through Summit Racing is the logistics. Shipping a 400+ lb engine block is no small feat. Summit offers free shipping on this item to a commercial address or your local freight terminal, which can save you hundreds of dollars compared to smaller engine builders.
Note: Always check the "Estimated Ship Date" on the product page. High demand for these units can sometimes lead to wait times, so planning your build schedule accordingly is wise.
Conclusion: The Best Value in Horsepower?
The Summit Racing™ Chevy LS 5.3L 450HP Long Block Crate Engine represents a sweet spot in the aftermarket, offering a perfect balance of performance, reliability, and affordability. For enthusiasts who have decided to upgrade their project cars or trucks, this engine delivers significantly more power than a stock replacement, while avoiding the risks associated with used engines. Plus, it comes at a fraction of the cost of a custom-built racing crate motor, making it an attractive option for builders and drivers alike.
For the project car builder who wants to turn the key and go, or the truck owner who needs to tow with authority and rip onto the freeway, this engine is a proven solution. It eliminates the problem of guesswork in the build process, allowing you to focus on the best part of the hobby: the drive.
With a hydraulic roller camshaft and a 24x crank reluctor, this crate engine long block is designed for seamless integration into a variety of models, ensuring compatibility and ease of installation. Whether you're building a street machine or a weekend warrior, Summit Racing Equipment has you covered.
Summit Racing's Pro LS line takes performance to the next level with forged internal components, making it ideal for high-power builds and forced induction applications. For those looking to push the limits, Edelbrock E-Force GM Truck and SUV Stage 1 supercharger kits and Hot Side Turbo Combo Kits are available, supporting power levels up to and over 1,000 HP.
If you're aiming for turbo applications, Summit Racing's kit configurations can handle over 1,200 HP, thanks to 4340 forged steel cranks, H-beam rods with ARP 2000 bolts, and other premium components. To ensure everything runs smoothly, aftermarket ECU tuning systems like the Holley Terminator X MAX allow for proper tuning of performance parts and forced induction setups.
If you're ready to transform your ride, Summit Racing Equipment makes it easy to get started. From crate engines to flywheels and tuning systems, they offer everything you need to remove the hassle from your build. Optional upgrades and configurations are available to suit your specific needs, and their team is ready to help with any issue or question you might have.
Don't let a problem hold you back. Email Summit Racing today or sign up for updates to stay informed about the latest products and availability. Whether you're building for speed, power, or reliability, Summit Racing has the parts and expertise to make your project a success.
Thank you for reading!
Your friend,
Todd
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