The High 5! Building a 500 Horsepower All-Motor 5.3L LS

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.

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.

• Summit Racing Pro LS Automotive Camshaft, Stage 4, P/N SUM-8711R1

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.

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).

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!

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.

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.

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).

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.

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.

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.

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!

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!