5.3 LS Build Combinations: Recipes for 400-700+ HP
What is the Best 5.3 LS Engine?
A stock 5.3L LS is factory rated around 320 hp and 340 lb-ft of torque, give or take, depending upon the application and model year of the donor vehicle. That’s a great starting point in anyone’s build plans, but like any gearhead, we want more. The good news is that when it comes to a budget 5.3 LS build, you can make some great power without spending thousands of dollars to do it. The popular LS 5.3 junkyard build has been well documented all over the Internet and YouTube, so we’re going to focus on the best starting point for your build and then break down popular horsepower thresholds and what it takes to reach them.
So where do you start with your 5.3 LS performance build? Finding a cheap 5.3 LS build candidate is often as easy as hitting your favorite salvage yard. There are tens of thousands of GM vehicles ripe for picking. Start your budget 5.3 LS build off with one of these salvage yard finds and you’ll already be saving money you can put toward performance parts to hit that magic horsepower number you’re after. But what is the best 5.3 LS for your intended project? Hands down the most popular LS 5.3 junkyard build fodder is going to be an LM7 build. What’s an LM7? It is an iron block Gen 3 5.3 LS used in the 1999-2007 Chevy trucks, vans, and SUVs (8th digit of the VIN will be a T), which means they are very plentiful and cheap! From a marketing standpoint GM called them the Vortec 5300, and the plastic engine cover makes them easy to spot. A low buck LM7 build makes for a great budget LS project.
But what about other LS 5.3 junkyard build options? There are certainly other options out there, such as the 2003-2005 LM4 (8th digit of the VIN will be a P). The LM4, also a Gen 3 engine, is essentially the same as the LM7 but built in an aluminum block. If you’re considering boost or high horsepower use, the iron block LM7 is undoubtedly stronger, but if you’re looking to do a simple cam swap and want to keep weight down for your hot rod build, the aluminum block LM4 is a very suitable choice for that, so certainly consider an LM4 build if you’re not going to add boost. Both the LM7 and LM4 can be found with the superior 706 GM aluminum head castings as well, which is a nice bonus. If you aren’t worried about the iron block weight, doing an LM7 build gives you room to breathe if you decide on boost later
Moving into the Gen 4 5.3 LS engines you have a couple of options here as well, though you will have to address GM’s Active Fuel Management/Displacement on Demand headache with many of these engines, which are based on aluminum blocks, along with the drive by wire throttle body. You can delete the AFM with one of our AFM delete kits. GM’s LC9 5.3 LS is found in 2007-2011 full size trucks and SUVs (8th digit of the VIN will be a 3). The LH6 is another budget 5.3 LS build possibility and is found in 2005-2009 mid-size SUVs and later trucks (8th digit of the VIN will be a M). Either of these are viable options for a 5.3 LS N/A build plan. An LH6 build or LC9 5.3 build is popular for those on a budget just looking to make a nice 400-450 HP for a cheap LS 5.3 junkyard build. Any of these will work in a classic hot rod or muscle car using one of our LS swap oil pans for clearance.
The one Gen 4 5.3 LS we do not recommend using is the LS4. This is a FWD application used in 2005-2009 cars (think Monte Carlo SS, Impala SS, etc.) and has several factors that make swapping into a rear drive platform a hassle. One of which is bellhousing bolt pattern. Unless you’re looking to do some sort of crazy rear engine build or have an old Pontiac Fiero lying around, we highly recommend skipping the LS4 variant. If you have any concerns about just what you’re looking at under the hood of that truck or SUV at the salvage yard, our LS engine identification guide will help with its VIN code list, engine specs, and more.
How Much HP Can a 5.3 LS Make?
If you’ve been researching a 5.3 LS build for boost for any length of time you’ve no doubt spent considerable time watching YouTube videos and reading online magazine articles from Hot Rod and other reputable channels. You’ve probably seen the same Richard Holdener video we’ve seen showing a stock, high mileage 5.3 LS shrug off 24 pounds of twin turbo boost and stay in one piece; making 1,300 plus horsepower along the way. Stuff like that makes for great clicks/views and subscribers, but will it do a burnout? Well, the obvious answer is yes, what we really should be asking is, will it survive on the street in a real installation you have in mind. That’s debatable. So, how much hp can a 5.3 LS handle?
So, let’s just say that, yes, a 5.3 LS can make upwards of four digit horsepower if you really want to. Maybe the real question here should be how much HP can a 5.3 LS make and live a long healthy life under the hood of your project? For that answer we’re going to be much more conservative and say anything over 500 horsepower and you’re looking at major internal upgrades, adding boost, and more, all of which starts to heat up the wallet exponentially. You must be honest with your budget, your project needs, and your expectations. Do we all want a 1,000 hp 5.3 LS stroker build with twin turbos for bragging rights? Sure we do but having a heads/cam/intake 5.3 LS build making 500 plus horsepower in your classic Camaro or Chevelle is still going to make more than the factory big block ever put to the ground and your wallet will thank you for the savings (which can be used for brakes and tires to keep all that power under control!). A single turbo LM7 build is actually pretty easy on the wallet though, just make sure you have the fuel system and other bits to support it. To summarize, a stock 5.3 will make about 320 HP. It's possible to push 1000 HP from a 5.3 LS, but a great budget build will easily get you 400-500 HP.
What Fuel System Is Needed to Support My Horsepower?
Below you will find “recipes” for popular horsepower levels for a 5.3 LS performance build. It is surprisingly easy to scratch that 400 horsepower itch with little more than a cam swap when it comes to the budget 5.3 LS build, just note that at that power level you’re close to maxing out the stock injectors and fuel delivery system. In most cases we’re talking about a classic vehicle 5.3 LS swap, so the fuel delivery system will be a new purchase anyway (we offer a great line of application specific EFI fuel tanks for builds like these that include an in-tank fuel pump. Just add a regulator, and fuel lines to complete your LS swap fuel system.
The injectors though are a different story. Changing injectors to support more horsepower gets a little tricky due to the different injectors the 5.3 LS came with over the years. Depending upon OE application there are three different injector wiring connector styles and several injector heights. When shopping for EFI fuel injectors you’ll have to keep this in mind, as your original wiring, or aftermarket EFI wiring may require a specific injector connector type. You can find injector connector adapters available online or carefully swap out the connectors and terminals on your harness, but your best bet is to know what injector your harness uses and buy the proper injector from the start. For example, our LM7 LS engine swap harnesses use Multec 2 style injector connectors.
As for the height differences, sometimes this can be made up using fuel rail or injector spacers that can be used to make up the difference for short or long injector bodies. This is usually only a problem when using stock truck injectors on a car intake, or vice versa, but just know that injectors are often a stumbling block when putting together a higher horsepower 5.3 LS build. We recommend new aftermarket injectors versus trying to cobble together used injectors that may have different flow rates, as GM is famous for making small injector changes during production. A 1999 truck 5.3 injector may be different than a 2007 5.3 truck injector.
400 HP 5.3 LS Build Parts List
400HP 5.3 LS Build Parts List (view cost and availability)
Notes:
If you’re not looking to deal with changing valve springs you can opt for the “no springs required” or NSR version of the BTR Truck Norris camshaft. The NSR Truck Norris cam works with the stock valve springs and will save you a few bucks in your budget 5.3 LS build.
450 HP 5.3 LS Build Parts List
450HP 5.3 LS Build Parts List (view cost and availability)
Notes:
If you do not have the tools to install the trunnion upgrade kit, we do offer a more complete solution with trunnion upgrade hardware, valve spring compressor tool, and trunnion installation tool. This trunnion kit with tools makes the upgrade go smoothly if you’ve never performed this modification before.
The Trailblazer SS intake does not include fuel rails. You will either need to source the OEM fuel rail or use aftermarket rails like Holley’s LS truck intake fuel rail kit.
If you do not have a throttle body to transfer IAC and TPS sensors you can substitute the FiTech 92mm throttle body for the Holley one listed, as it comes complete.
500 HP 5.3 LS Build Parts List
500HP 5.3 LS Build Parts List (view cost and availability)
Notes:
This nitrous kit ships with 100, 125, and 150 horsepower jets, which is more than enough to make 500 horsepower at the crank. The kit will support up to a 175 HP boost with optional jetting. Many aftermarket EFI systems offer built-in control for nitrous systems.
600 HP 5.3 LS Build Parts List (Turbo)
600HP 5.3 LS Build Parts List (Turbo) (view cost and availability)
Notes:
The Hooker cast iron turbo manifolds work with Hooker's line of transmission specific exhaust crossover tubes to create a bolt on turbo exhaust.
For your cold side turbo build needs we offer 3-inch cold side tubing and 3-inch tubing couplers to make the connection from the turbo to the engine’s throttle body.
For a more efficient inlet charge (and more horsepower) adding an intercooler is a great option if you have the room to mount it.
This VS Racing turbo features a 4-inch inlet. We offer conical air filters with a 4-inch clamp base for direct mount to the turbo.
600 HP 5.3 LS Build Parts List (Nitrous)
600HP 5.3 LS Build Parts List (Nitrous) (view cost and availability)
Notes:
This nitrous kit ships with 100, 125, and 150 horsepower jets, which is more than enough to make 600 horsepower at the crank. The kit will support up to a 175 HP boost with optional jetting. Many aftermarket EFI systems offer built-in control for nitrous systems.
700 HP 5.3 LS Build Parts List
- Elgin Sloppy Mechanics Stage 2 Cam
- Pac 1218 Valve Springs
- PRW Trunnion Upgrade Kit
- GM Balancer Bolt
- Full LS Gasket Set
- Speedmaster 1997-2003 Head Stud Kit
- LS7 Roller Lifters (order two quantity)
- LS7 Lifter trays (order four quantity)
- GM Replacement Timing Chain
- VS Racing Nex Gen 7875 Turbo
- VS Racing 50mm Wastegate
- Hooker Single Turbo Exhaust Manifold Kit
700HP 5.3 LS Build Parts List (view cost and availability)
Notes:
The Hooker cast iron turbo manifolds work with Hooker’s line of transmission specific exhaust crossover tubes to create a bolt on turbo exhaust.
For your cold side turbo build needs we offer 3-inch cold side tubing and 3-inch tubing couplers to make the connection from the turbo to the engine’s throttle body.
For a more efficient inlet charge (and more horsepower) adding an intercooler is a great option if you have the room to mount it.
This VS Racing turbo features a 4-inch inlet. We offer conical air filters with a 4-inch clamp base for direct mount to the turbo.
Helpful Tools for Your 5.3 LS Build
The LS engine family is an easy engine to work on, but there are a few special tools that always make things go more smoothly out in the garage, be it mocking up an LS swap, or just handling a cam swap in the car. These are some of our picks that will help get the job done and keep things moving forward.
