We all know that making big power with an LS is as easy as adding boost, right? In fact, the recipe for huge power is to add cam, springs, and boost. Of course this assumes a number of things like large enough injectors and pump, intercooling and the proper tune (hopefully with E85).

What about the enthusiasts who want to go the all-motor route?

I can hear the turbo crowd cringe, but the reality is that not everyone wants boost. So, we decided to illustrate what it takes to exceed 500 (flywheel) horsepower with off-the-shelf components on a 5.3L LS engine.

We all know that making big power with boost is easy, but what about all-motor LS power? (Image/Richard Holdener)

Why Choose a 5.3L?

Sure, it would be much easier to produce the desired 500 hp with almost any run-of-the-mill 6.0L (LQ4, LQ9, LY6, etc.). In fact, all it takes is the right cam on a 6.0L, but the problem with the bigger motor is they are more expensive and harder to find. Bigger is certainly better, but so too does it require a deeper wallet.

By contrast, wrecking yards are literally full of base 4.8L and 5.3L engines. On my last trip, I counted over a dozen LR4 and LM7 combos just begging for new homes. Noticeably absent were any 6.0L and 6.2L engines—or any aluminum motors for that matter!

When it comes to availability, the 4.8L and 5.3L LS reign supreme, and since bigger is better, why not start with the 5.3L?

Learn more about each LS engine displacement:
* 4.8L LS Engine Guide: Block Specs, Swap Resources & Build Info
* 5.3L LS Engine Guide: Block Specs, Swap Resources & Build Info
* 5.7L LS Engine Guide: Block Specs, Swap Resources & Build Info
* 6.0L LS Engine Guide: Block Specs, Swap Resources & Build Info
* 6.2L LS Engine Guide: Block Specs, Swap Resources & Build Info
* 7.0L LS Engine Guide: Block Specs, Swap Resources & Build Info

500 HP 5.3L LS Engine Block

Truth be told, our test motor did not come from a junkyard, but instead was supplied by the good folks at Strictly Performance. The boost-ready motor was perfect for the intended purpose (we originally planned to run a Big Bang Test on it), but prior to running boost (actually during), we took the opportunity to test out the big Stage 4 cam from Summit Racing.

Unlike our typical starting point that involved a trip to the junkyard to find a greasy, grimy, high-mileage motor of questionable potential, this long block started out life as a rebuilt unit from Strictly Performance. (Image/Richard Holdener)

Though new (or rebuilt), the Strictly Performance 5.3L featured a stock iron block and cast crank combined with production Gen. 4 rods (which we’ve previously taken to 1,543 hp!) and hard anodized, cast pistons.

Think of the short block as a boost ready stock bottom end…sort of.

Designed for power adder use (my original plan was to do a Big Bang with it), the 5.3L from Strictly Performance featured a stock iron block, a cast crank, Gen. 4 rods, and hard anodized cast pistons. (Image/Richard Holdener)

500 HP 5.3L LS Cylinder Heads & Valvetrain

To help make power, the SP 5.3L also featured a set of ported 706 heads. Katech provided the porting for the 706 heads, though the porting program retained the factory valve sizes. Given our sizable cam choice, the Katech 706 heads were also treated to a dual valve spring package from Brian Tooley Racing, stock rockers, and hardened Trend Pushrods (7.35 inch).

For this test, the SP 5.3L LS was equipped a dual-spring upgrade from Brian Tooley Racing, combined with the stock rockers and hardened pushrods. (Image/Richard Holdener)

The 5.3L from Strictly Performance was finished off with the same components you might find on any junkyard motor, including a truck oil pan and pickup, front and rear cover, and matching valve covers. While swapping out the LS9 cam used for a previous test, we also replaced the factory damper with an eight-rib unit from ATI to later work with a Vortech Supercharger.

While the SP 5.3L differed slightly from your run of the mill junkyard 5.3L, the mods performed to the motor would certainly work just as well on any 5.3L LS. Simply having a 5.3L is one thing, but having a 5.3L that exceeds 500 hp is another animal altogether. The 5.3L from Strictly Performance already had one advantage, in the form of the Katech ported 706 heads.

You see, the route to improved performance goes through the Big Three, otherwise known as the heads, cam, and intake!

The 5.3L from Strictly Performance featured a set of Katech ported 706 heads that retained the factory 706 valve sizes. (Image/Richard Holdener)

500 HP 5.3L LS Camshaft & Intake

With additional head flow already at our fingertips, all we need to do was address the intake and cam timing. Wanting big power, we selected a Stage 4 cam from Summit Racing, part number SUM-8711R1.

To help improve our chances of eclipsing the 500 hp mark, we selected a Stage 4 cam from Summit Racing. The Summit Racing Pro LS Stage 4 cam offered a .625/.605 lift split, a 234/247 degree LSA an 113+3.5 LSA. (Image/Richard Holdener)

Part of the Summit Racing Pro LS Cam lineup, this Stage 4 option offers a .625/.605 lift split, a 234/247 degree LSA, and a 113+3.5 LSA. Consider this at or near the limit of available piston-to-valve clearance when it comes to running it with a piston that does not have available valve reliefs! The cam not only allowed plenty of breathing to take advantage of the extra airflow offered by the ported Katech heads, but also plenty of rpm to help reach our desired 500 hp mark.

The motor was originally run with the factory truck intake, but our quest for power eventually pushed us to try something much better. (Image/Richard Holdener)

Finishing off the terrible trio was a FAST LSXR intake manifold and matching 102mm Big Mouth throttle body. Considerably more powerful than the factory truck intake, the FAST model offers more peak power along with a healthy torque curve (courtesy of its long runners).

We replaced the factory truck intake and throttle body with a FAST LSXR intake. The FAST intake has also proven itself much more powerful than the truck intake. (Image/Richard Holdener)
Working with the FAST intake was the matching FAST 102mm Big Mouth throttle body. (Image/Richard Holdener)

Finishing & Dyno Testing the 500 HP 5.3L LS

With our FAST LSXR intake and throttle body, ported Katech heads, and Summit Racing Pro LS Stage 4 cam, the SP 5.3L was really coming together.

FAST also supplied the required 75 pound injectors and billet-aluminum fuel rails. (Image/Richard Holdener)

The finishing touches included new lifters, plus fuel rails and 75 pound injectors from FAST, along with a set of 1-7/8 inch, long tube Hooker Headers. The headers were run with collector extensions to help simulate a complete exhaust, but mostly to enhance torque production down low.

All testing was performed with a set of 1-7/8 inch, long tube Hooker headers feeding a pair of 18 to 20 inch collector extensions, which help low-speed torque but sacrifice no peak power. (Image/Richard Holdener)

The basic SP 5.3L was given a break-in procedure long ago, and required only tuning to start making some serious power. Running a Holley engine management system, we dialed in the air/fuel mixture (12.9:1) and timing curves (29 to 30 degrees total at the horsepower peak).

We were eventually rewarded with peak numbers of 508.6 hp at 6,700 rpm and 435.7 lb.-ft. of torque at 5,700 rpm.

Knowing the tune was a critical element in our quest for 500 horsepower, we dialed in our SP 5.3L combo a Holley HP management system. (Image/Richard Holdener)

The specific (peak hp) output of 1.568 hp per inch was impressive, but so too was the fact that the modified 5.3L offered a broad torque curve. Torque production exceeded 400 lb.-ft. from 3,800 rpm all the way out to 6,700 rpm!

Naturally the new combo required proper tuning. The author utilized a Holley HP management system to tune the AF and timing curves on the modified 5.3L. (Image/Richard Holdener)

Not only did the HCI 5.3L offer impressive peak power and torque numbers, it delivered a broad, usable curve you could enjoy without having to ring it out for all it’s worth! After the test of this 500 hp, all-motor 5.3L, there were literally High Fives all around!

When it comes to maximizing the power output of a LS motor, you need to employ what can best be described as the Big Three! Sure, you can make some big power gains with the right cam on your average junkyard 5.3L, but to really make power, you will need to throw in a good intake and ported heads. In this case, we combined a healthy cam profile (meaning far from stock converter friendly) in the form of the Summit Racing Stage 4. The big cam was combined with ported 706 heads from Katech and a Fast LSXR intake and 102mm throttle body. The big three naturally received a set of long-tube (1-7/8 inch) headers to maximize exhaust scavenging and optimize power production. Once tuned, the modified 5.3L from Strictly Performance belted out an impressive 508.6 hp at 6,700 rpm and 435.7 lb.-ft. of torque at 5,700 rpm. Far from a top-end only combo, the 5.3L offered 400 lb.-ft .of torque from 3,800 rpm to 6,700 rpm. (Dyno Chart/Richard Holdener)
Because the motor had been run previously with a much smaller (factory LS9) cam, we replaced the mild LS9 with our Summit Racing Pro LS Stage 4. Off came the water pump and truck damper to provide access to the front cover. (Image/Richard Holdener)
Removal of the cover provided access to the three bolts securing the timing chain behind the factory oil pump. Note the motor was positioned with Number One piston at TDC (dots lined up on cam and crank pulleys). (Image/Richard Holdener)
Removal of the three cam gear bolts allowed access to the four bolts securing the cam retaining plate. On high-mileage LS motors, make sure to check the condition of the O-ring seal on the back of the plate—junkyard scavengers know what we’re talking about here. (Image/Richard Holdener)
Off came the plate to allow removal of the LS9 cam from a previous test. Since the lifter trays were new, it was possible to simply spin the cam to push the lifters in place for the swap. The new trays will secure the lifters in place to facilitate the cam swap. Take care when doing this on high-mileage motors, as the lifter trays often will not hold the lifters in place and, if they drop, you have to disassemble the motor to fetch them. (Image/Richard Holdener)
Out came the LS9 cam and in went the Summit Racing Pro LS Stage 4. We took the liberty of oiling the cam journals and lobes prior to assembly. Note the lifter retaining tools used on this cam swap. (Image/Richard Holdener)
After the cam swap, we installed the front cover and positioned it with the damper. The stock damper was later swapped out for an ATI unit. (Image/Richard Holdener)
Run on the dyno with the FAST LSXR intake, Katech-ported 706 heads and Summit Racing Pro LS Stage 4 cam, the Strictly Performance 5.3L produced 508.6 hp at 6,700 rpm and 445.7 lb-ft of torque at 57,00 rpm.

Keywords
5.3L LS, FAST, Holley, LS Engine, Pro LS
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Author: Richard Holdener

Richard Holdener is a technical editor with over 25 years of hands-on experience in the automotive industry. He's authored several books on performance engine building and written numerous articles for publications like Hot Rod, Car Craft, Super Chevy, Power & Performance, GM High Tech, and many others.