Salvage Yard Superhero

Part II: Topping off our bored and stroked 5.3L

Story Andy Bolig / Images Jeff Gardner - July 25, 2013 10:00 AM


1 The COMP LSr camshaft family was designed for today’s LS engines. As such, we installed the camshaft “straight up” with no advance or retarding the cam’s timing.


2 The flow bench revealed that our heads fell a little short of keeping up with our .600-inch-plus lift camshaft.


3 With just a little bit of bowl and short-side work, Jeff had our heads up to the task.


4 In assembling the heads, Jeff checked the installed height of the GM-supplied valves.


5 COMP Cams’ Elite Drag Race daul valve springs (p/n 26955-16) are engineered to improve durability and spring life for extreme-duty applications.


6 A Mr. Gasket head gasket (p/n 5713G) seals off the combustion chambers.


7 To keep them close, even under pressure, ARP head bolts were utilized.


8 COMP Cams offers a trunion rebuild kit (p/n 13702-KIT) for the factory rocker arms. This kit converts a stock GM rocker arm into a roller trunion rocker.


9 Our FAST LSXR 102mm intake is sure to breathe enough for each of those 500-plus ponies. Plus, it features lightweight construction, removable runners and it fits under most hoods!


10 Bigger is NOT always better and our street-driver only needed a 92mm FAST throttle body to meet our milestone.


11 We finished off the engine with various GM sensors, a set of 36 lb-hr FAST injectors and fuel rails and since the LS family of engines use a coil pack for each plug, a set of eight high-performance coils were installed from WeaponX, to be sure all that fuel burned in the cylinders!


12 Even fresh engines need protection, so we contacted Royal Purple for enough of their Engine Break-In Oil to protect our engine on the dyno.


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Our little engine that MIGHT comes together for a full-on dyno flog.

In Part One, we laid the foundation for our 500-horse small-block LS engine. We explained some reasons why we decided to go with an iron-block 5.3L engine, rather than a more-popular 6-litre version. We blurred the line between the two slightly by increasing both the bore and stroke of our engine, giving it 364 cubes instead of the factory-installed 324.

That additional power potential under the surface means that we needed to figure out a more efficient way of feeding each of those 500 horses. It takes more than a big opening to make power from a naturally aspirated engine; it takes vacuum, volume and velocity of air to make sure that fuel mixture gets burned completely. That is one of the benefits of LS-based engines.

The heads used on virtually every LS engine have benefitted from GM’s engineering at their powertrain facilities and, while they all can stand head and shoulders above many of their contemporaries, that doesn’t mean that every LSx head is a good fit for any engine in that family. Due to the bore sizing of our engine (3.800 inches), we were limited from using the latest and greatest rectangular-ported LS3 heads because of their requirement of a four-inch bore. We went with a bare casting of GM’s LS2/LS6 heads from Chevrolet Performance, as their cathedral ports work well and they would fit well over our increased, but not oversized, bores without shrouding the valves in the cylinders.

Above the heads, we needed to increase the amount of airflow with a FAST LSXR intake (p/n 146302). This intake is designed for car applications, so it will fit under the hoods of almost any car, and it is designed to handle up to the huge 102mm throttle bodies available for these engines, but our engine would easily suffice with their 92mm throttle body to keep both air volume and velocities high. We also opted for the additional fuel rails (p/n 146033-KIT).

Additional parts and pieces began coming together at Gardner Competition Engines and it was time to begin making all of the newly acquired components work together to reach our half-thousand of horsepower goal. As mentioned in Part 1, Gardner’s installed a COMP Cams’ 281LR HR13 grind (p/n 54-459-11) with .617-inch lift on the intake and .624-inch on the exhaust. To make sure that everything above the heads worked in unison with everything going on underneath, a matching set of pushrods, valve springs and retainers were ordered. The Chevrolet Performance lifters retained their rolling duties.

Not to leave anything to chance, Jeff Gardner put the bare head castings (p/n 12629049) on their flow bench just to see what kind of air they would be moving under power. At right around .500-inch lift, Jeff reports that the heads’ airflow “stalled”. Keeping in mind that our camshaft carries over .600-inch of lift, if we were to ever make use of all that the camshaft has to offer, even these great flowing heads would need a little bit of work. Jeff proceeded to clean up the bowls and entry into the combustion chambers to help them carry all of the airflow that our stroker engine would need.

As the engine started coming together, hopes were high that we would be able to obtain our 500hp goal and, with the increased size of our engine, we were not only confident in our little engine, but also that it could be done in a package that would be well suited for the street. As the engine fired up on the dyno for the first time, it became obvious that our little engine could produce. There’s no doubt that this LS-based engine is still a performance powerhouse. It settles into a nice, lumpy idle that assuredly lets everyone know that this little truck engine still hauls!

The Holley HP EFI unit brought the engine right into tune and with minor adjustments to our particular configuration, we were up and running against the dyno. Our first pull put us over our 500 hp hurdle at 5,600 rpm and steadily rose until topping out at 6,300, with 518 hp. Torque at 3,500 rpm (where we began testing) was a strong 443 lbs-ft and carried until its peak at 5,100 rpm, where it topped out at 478 lbs-ft. We were happy in that we had met our goal, but we wanted to find out if there was more to be had in fine-tuning the Holley system.

Our second session with the dyno netted numbers that were only slightly higher averages than our first pulls and only by one or two, a testament to the accuracy of the Holley EFI wide-band capability in accuracy. Peak numbers remained the same and merely moved up or down a few rpm throughout the testing, which occurred from 3,500 to 7,000 rpm. Highest numbers for both horsepower and torque settled in at 520 hp at 6,200 rpm and 480 lbs-ft at 4,800 rpm.

Clearly, our little engine has proven itself. We were happy to see that with the right combination, horsepower numbers that were once relegated to race-only applications can now be realized on a regular basis on the streets of today. The best part is, with all the benefits built into the original foundation of the LSx engine platform, you can have all this available horsepower without giving up all the modern benefits of power accessories, drivability, repairability AND relative fuel efficiency!

Surely the small-block Chevrolet engine has secured itself through all of its previous generations as a reliable form of performance, and, as our little salvage yard superhero has shown, this latest generation is sure to stay.


Digital Horsepower

The automotive aftermarket is full of products engineered to increase performance. Camshafts, pistons, crankshafts and clutches all play a major part in making power. But the reality of today’s fuel-injected engines is that all of those components will never see their full potential unless you digitally fine-tune the engine’s diet of fuel.

Electronic Fuel Injection has come a long way in recent years and advancements like full-time wide-band sensing and faster componentry has provided the enthusiast with electronic fuel injection systems that are not only tunable, but quite capable.

We utilized a Holley HP EFI unit for our LS-based engine, but they also offer systems designed for TPI, TBI and also a retro-fit system for those upgrading from a carbureted engine in their ride. Standard features in the HP system include four programmable inputs and outputs, boost and nitrous control, timing retard, meth-injection control, fuel pump control and one to five bar MAP sensor capability for boosted applications. Their new V2 programming includes data logging, integrated boost control and available traction control.

Many of today’s EFI controllers are pre-equipped in their programming for many applications and the Holley HP is no different. There are drop-down menus for many applications and after inserting all the pertinent information about your particular engine, the computer chooses a tune that closely matches your engine’s needs. Upon firing the engine, the computer utilizes a self-tuning, which then brings your engine’s fuel needs even more closely into pinpoint accuracy. For those who choose to go even further and try and find each and every horse hiding under their hood, there are adjustable fuel and spark tables, as well as other tuning parameters.

The HP EFI controller is quite capable but, if you find that your needs also include electronic transmission controls, you can get all this and more in Holley’s Dominator EFI unit. Since we were concerned with only running the engine, we opted for the HP.

For Your Information:


Gardner Competition Engines

(440) 635-0495


K1 Technologies

(440) 497-3100



(800) 321-1364



(270) 782-2900



(877) 334-8355



(800) 999-0853


Mr. Gasket

(216) 688-8300



(517) 787-8172


Automotive Racing Products

(800) 826-3045



(519) 341-4125


Chevrolet Performance


Royal Purple

(888) 382-6300


Rock Auto

(608) 661-1376