Unleashing Power: Building a 500HP GM Stroker Engine – Exploring the Battle Between Old School Chevy Small-Block and Modern LS Series

MARCEL VENABLE . May 24, 2023 . Chevrolet

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What It Takes to Build a 500HP GM Stroker Engine

The debate rages between champions of the old school Chevy small-block and fans of the new-school LS series. Which camp do you fall into? When you really take a look at both power plants they’re not that different in the component category. As a matter of fact, many of the rotating internals share the same dimensions if you decide to hop up one of them.

Obviously GM improved some key features when it introduced the LS series engine in late 1997. The redesigned main caps and side-loading bosses improved the block’s strength; and the noticeable lack of distributor, traded for the individual coil packs devoted to each cylinder, made the LS look completely different, and it took a few years for hot rodders to learn how to build power with it. However, hands down, the one major improvement that the LS series has over the small-block Chevy is improved cylinder head design.

So the debate continues: Is the LS series better thanks to more modern technology and engineering? Well, I wouldn’t count out the ol’ small-block Chevy just yet. There’s no question that this engine design has received more research than a NASA rocket ever did. The small-block Chevy is a freak of nature, and it’s surpassed its original design limitations 10 times over. From the days of 265 ci, to today’s 500-ci monster motors, the small-block Chevy is a tough competitor to beat.

OK, I know what you’re really thinking, which one is better, or which one can I make more power with? Well, the answer really is both, because each design is capable of making more power than anyone could ever use, or should have on the street, and because of their production numbers and the availability of aftermarket speed parts, building a performance GM-based engine is the easiest and most affordable option today.

Now let’s focus on how to get the most out of a GM engine whether it’s based on a small-block Chevy or an LS. I’m sure that all of us motorheads know that increasing the displacement in any engine will benefit the horsepower output. There are many ways to increase engine displacement, but the least invasive method is to change the crankshaft’s stroke length. Referred to as “stroking the crank” or “building a stroker,” it’s by far the simplest way to increase the displacement of a performance engine and yield the biggest gains.

If you haven’t heard the term “stroker engine” before, then let me welcome you to world of the 21st century performance vehicle. But, I’ll bet that you have heard the term, so instead, here’s a little background information on one of the most popular engine modifications known to gearhead kind. Let’s start from the beginning: What is a stroker engine really, and why has it been so popular for most of the last 40 years.

Back in the day, drag racers and dirt track racers were in need of a low-buck way to increase horsepower. Racing is an expensive sport, and most spend a fortune on parts to make their vehicle faster. In the late-’60s and early-’70s, the Chevy small-block engine, or the SBC, was the reigning king of power plants in just about everything on four wheels. The SBC was offered in many different cubic inch sizes, including the ever-popular 350-cid passenger car model, as well as the 400-cid model found in some station wagon and truck models. The racer of this time had to be savvy and unafraid of experimentation to gain maximum horsepower from these engines.

It didn’t take long to figure out how to merge the two engines together. The 400 crankshaft had a stroke length over the 350’s crank, when it was installed into the 350 block, it increased the overall displacement size from 350 to 382.7 ci, which when rounded up turned into what we know as the 383 stroker. The result was an increase in the distance that a piston has to travel up and down in the cylinder bore, which literally increases engine displacement or engine size, creating extra power. This changed everything. As the saying goes, there is no replacement for displacement. From that point on hundreds of thousands have been built. It wasn’t long after that other engines were stroked, like Fords, Mopars, imports and even diesel engines. The mod became the poor man’s race engine and started the street performance revolution.

Throughout the years, many paid for the abuse they were inflicting onto their factory parts. Stock cast components were no match for the high rpm requirements. Parts began to fail, which opened the door for aftermarket companies to improve parts and increase the numbers of this sought-after combination. Stronger forged parts made their way into machine shops, as well as new piston and cylinder head designs, which increased numbers and soon surpassed the old square engine benchmark of 383 hp. In fact it’s not unheard of for engine numbers to surpass 500 hp, street driven on pump gas. The best part of this whole grand experiment is the fact that engine builders didn’t quit at 382.7 ci. It’s now pretty common to change bore size to a larger diameter or even increase the stroke to gain more cubic inches. Many aftermarket parts manufacturers now offer a variety of different sizes of crankshafts and connecting rod lengths that will change overall displacement size. One of the most popular engines to stroke today is the LS series engine which shares some of the same principles of the earlier SBC design.

We wanted to get a better idea of what makes a good stroker combination, as well as what it takes to build one. What we discovered is that there is a ton of information out there to digest and a few different options depending on what your truck already has. To give our readers a better idea of the options that are available, we decided to look into building a pair of the most commonly stroked engines. One is the conventional SBC with 383 cubic inches, and the other is the latest popular stroker combination, a 6.0L LS truck engine stroked out to 408 ci.

LS ENGINE: 2002 6L IRON TRUCK BLOCK STROKED FROM 364 CID TO 408 CID

1. In order to build a strong engine, you’ll need to start right at the block. We had this iron 6L LS block sonically cleaned and tested for cracks prior to the machining process over at Clovis Machine Shop in Clovis, CA. Next the block’s main crank journal and main caps were checked for square using an align-honing bar. The cylinders got a fresh hone job to ensure that the new piston rings seat properly. Then the deck height of the top of the block was squared down .005 and cleaned thoroughly before assembly began.

2. Big-horsepower engines place a huge load on the fasteners that hold them together. It’s essential to upgrade your engine’s fasteners if you plan on making power. ARP has been an industry leader in performance fasteners for more than 40 years. This engine stud and bolt kit has all of the proper mounting fasteners, providing the user with piece of mind when they stand on the throttle of their favorite truck.

3. When building an engine to run in a high RPM range, proper engine bearing clearances are a must—multiple sets of bearings may be required. Our engine builder, Peter Guy, explained that when he assembles a high-performance engine he measures and matches bearings from multiple sets of Speed Pro bearings before setting them in place in the block.

4. We chose an Eagle Specialty Products’ 4340 forged steel crankshaft with 4.000 stroke. This crank trumps the 3.60 stroke length of the stock 370-ci 6L engine and features a 24-tooth reluctor wheel on the crank. This model features Eagle’s ESP armor coating, a top-secret process that evenly coats the entire crankshaft with a mirror-like finish that allows the oil to flow over the rotating crankshaft without any measurable drag, resulting in less friction and less power-robbing heat. Paired with Eagle’s 6.125-inch long forged H-beam-style connecting rod increases the displacement up to 408 ci!

5. Rounding out the rotating assembly is a set of Eagle’s H-beam connecting rods installed with ARP’s rod bolts, and Mahle forged aluminum pistons. Mahle’s reputation for delivering the highest quality forgings is evident just by looking at the pistons in the box. The pins and round wire clips for all eight slugs are included. We ordered the entire rotating assembly as a kit, which allowed Eagle to receive the pistons from Mahle to balance all of the rotating parts together to ensure more performance and a longer service life. The rotating internal parts are paired as closely as possible by weight before they are spun on a balancing machine to match them together by their overall weight.

6. Next, our tech hangs the Mahle pistons to the Eagle H-beam rods. If you think that the pistons are a strange color, you’re right. That’s a phosphate coating that helps reduce heat temperatures and friction that can cause cylinder wall wear and cuts down horsepower.

7. Now that all of the pistons have been hung on the rods it’s time to fit the rings and slip them into the cylinders to match them to the crankshaft.

8. Moving on to the installation of the Trick Flow Specialties camshaft, the camshaft bearings were installed at Clovis Machine. To prep for the installation, assembly lube was applied to the bearings and the camshaft prior to installing them on the block.

9. Next, we began the installation of Summit Racing’s adjustable double roller timing gear set. This is equipped with multiple keyway grooves to advance or retard the camshaft’s timing depending on the specs. The nine-position crank sprocket allows the installer to advance or retard the cam in 2-degree increments or straight up if need be.

**10.** Our cam specs demanded the timing set run straight up, so after we installed it we moved on to the high volume oil pump from Melling that we ordered from Summit’s website. This iron pump may seem like a step backward since most LS series engines are equipped with an aluminum pump for reducing the weight of the rotating mass. But, what some folks don’t realize is that the aluminum pumps expand at high rpms and cavitate, reducing oil pressure and flow. Their iron counterparts never expand during high rpm sessions, maintaining constant pressure and flow to the engine’s vital parts.

**11.** Trick Flow Specialties’ cathedral port aluminum cylinder heads feature 225 intake runners and a total 65cc of volume for the combustion chamber. These are the perfect choice for a big cubic inch engine because they are equipped with 2.055 intake valves and 1.575 exhaust valves. Matching it to the Trick Flow hydraulic roller camshaft that features a .595 lift/242 duration cam on a 112-lobe separation allows for maximum performance with a good idle and easy start up, perfect for a fuel-injected engine. Trick Flow’s push rods and Harland Sharp’s 1.7:1 roller rocker arms were installed and torqued down to 22 ft-lbs at zero lash.

**12.** ARP’s cylinder head stud kit was also used on the iron block and installed with ARP’s assembly lube before being turned into the block. Then Fel-Pro’s perma torque MLS series head gaskets were slid over the studs and into the block’s deck surface. This set measured .0041-inch rather than the stock .0053 gasket giving us a tighter clearance height to the top of the piston. To make sure that we were in no danger of valve interference, our tech used some modeling clay on the top of the piston where he installed a cylinder head, push rod and rocker arm to rotate the engine over. After the valves made a cycle, he removed the head to reveal whether or not the valve/piston were in any danger by measuring the impression left in the clay.

**13.** A FAST intake system delivers fuel injection, but not just any intake manifold for this stroker will do, because we want to see the torque number shoot sky high. We used FAST’s LSX-RT intake with its 102mm Big Mouth throttle body. The long intake runners will ensure that this engine makes big torque numbers and the 102mm Big Mouth throttle body can deliver the airflow needed to make it work right. Don’t be fooled by its plastic look, using a composite material ensures that this intake resists heat that can cause fuel to vaporize prior to traveling into the combustion chamber. Cooler fuel means more horsepower, so we’ll take the plastic intake over an aluminum job anytime.

**14.** A set of FAST fuel rails and 44-pound FAST injectors allow this beast to drink its fill of fuel when needed.

**15.** One of the LS’s greatest achievements is improved engine seals. Fel-Pro’s gaskets were a big part of the LS series’ gasket design. It’ll be easier on you if you purchase an engine kit rather than trying to piece things together. Here is Richard Ruiz from PPC Customs as he uses a straightedge to help align the cover to the block when installing the gasket and the timing cover.

**16.** The stock LS series truck pan works well on the stock Silverado only. In our case this engine will be making its way into an early C-10 pickup. Holley performance has recently introduced a boatload of conversion items for LS lovers to place their favorite engine into their favorite truck. Richard installs Holley’s conversion pan and oil pump tube using a Fel-Pro gasket.

**17.** Insurance to combat balancer failure is made possible via a Professional Products SFI-approved harmonic balancer. Using a harmonic balancer installation tool, Richard installs the balancer followed by an ARP crankshaft bolt. With everything in place, our LS series long-block is now complete!

**18.** Having the right fuel delivery system is paramount to building big horsepower numbers, as well as keeping your engine alive. One of the key features of the LS series engine is the factory fuel injection. FAST is the pro of LS fuel injection and ignition management. Its XFI series fuel/ignition computer allows everyone from the DIY’er to the professional tuner to control all of the vital engine requirements.

**19.** For the XFI to work so well, a high-performance fuel pump is a must-have. We looked into Holley’s new line of electric fuel pumps, along with its filter/regulator, which allows street-driven use, delivering enough fuel to feed up to a 900–hp engine without sounding like an airplane. This new pump runs quietly and coolly, which increases lifespan.

**20.** The coil packs and plug wires are often overlooked on LS series engines, primarily because the series is still a new concept for most engine builders. Throughout the past few years, LS engine builders have been in the know about the way in which individual coils feed each cylinder to make more power with more stored energy. MSD Ignition has engineered this coil pack series to deliver a higher output than OEM versions. Pair them with MSD’s wires and you’ll have clean, consistent spark to ignite fuel.

**21.** Don’’ forget that the longer stroke and added compression of a stroker means that more load will be placed on the engine’s starter motor. MSD has developed this extreme torque starter from its Dyna-Force line that features an adjustable billet mount, which has been blueprinted for longer service use.

**22.** Now that the 408 has been assembled we brought it over to JMS Racing Engines in El Monte, CA. JMS has been in the performance engine building game for decades, and we knew that it would find every bit of horsepower possible. Placing the LS on the shop’s dyno allowed us to set up the FAST XFI computer system and see how much power we have!

Small-block Chevrolet engine: blueprint iron block stroked to 383 cid

**23.** Stroker builds are now common among performance engine builders, so pre-clearanced SBC iron blocks can be ordered by engine houses such as Blueprint Engines. This late-model, one-piece rear main seal unit has already been prepped for the 3.75-inch crankshaft and was shipped to our door via truck freight. The greatest thing about this purchase is the fact that this block is ready to be cleaned and assembled since all of necessary machine work has already been done at Blueprint.

**24.** For this engine, we used a Scat forged 4340 steel crankshaft, as well as its forged H-beam rods featuring ARP bolts for added strength. All of its forged cranks are machined in-house on its CNC equipment, including the rods that are weighted in-house and paired for balancing. We chose Ross racing pistons for the build.

**25.** Scat also produces this SBC flex-plate that we will use during the balancing process and for the transmission.

**26.** The rotating assembly was sent to Scat for professional balancing. Total Seal piston rings and Speed Pro engine bearings were added to the menu. Once they were happy with the balancing results, we packed up everything including a Fluidampr harmonic balancer and began assembly.

**27(a).** Having a handicap of 25 less cubic inches means our shootout idea is really going to be put to the test.

**27(b).** We asked a few engine builders what they recommended to give the 383 a fighting chance against its LS younger brother. Air Flow Research’s 195 series head (P/N 1040) was the winner. It gives the engine the extra flow needed to make big power. These heads feature 195cc intake runners and hold 65cc in the combustion chamber. When paired to an Edelbrock Performer air gap manifold (P/N 75013) and a Holley 750-cfm carburetor, this creates a nice recipe for a streetable yet powerful SBC engine that will make all the power we want.

**28.** The valve train combination for our magic recipe is Comp Cam’s K08-432-8 camshaft. This hydraulic roller cam is set on a 110-lobe center for easy starts for a carbureted engine. Comp lifters and pushrods and Comp’s Magnum 1.52 ratio roller tip rocker arms make things happen. To ensure things stay true, a Comp Cams timing chain rounds out the valve train.

**29.** Reliable ignition plays a major role for an engine that isn’t computer controlled, such as our SBC stroker, so we chose to use MSD Ignition’s billet distributor, ignition box and coil and plug wire set. This extra bit of insurance will make us feel better about the lack of computer control of the engine’s timing during a high-rpm scenario.

**30.** Fel-Pro performance series gaskets were used again for this build, as they were for the LS build. Fel-Pro’s reputation as a performance gasket has always been based on the performance of its products found in engines in almost every racing league. The robust seal needed to contain the extreme combustion pressures means longer life for a performance engine.

**31.** Oil circulation is made possible for this engine via a Milodon oil pan pick-up and a Melling oil pump and drive setup. Oil circulation is key to the SBC and the Milodon deep pan offers 2 extra quarts of oil over a stock pan.

**32.** To keep the engine cool, a Weiand short aluminum water pump is bolted to the block.

**33.** Topping things off are these great-looking, tall valve covers, which allow enough clearance for Comp’s Magnum roller rocker arms. An aluminum timing chain cover offers leak-free service when paired with a Fel-Pro gasket.

**34.** The completed 383 SBC engine package. The carbureted setup keeps that old school sound and style, while keeping it on par with the power of the LS. The old saying there’s no replacement for displacement isn’t a myth. After Mark at Rapp Racing assembled the SBC, we drove it over to Paul Phaff Racing for use of their dyno to see how close our little 383 SBC would do against the 408 LS.

Tale of the Tape

LS		SBC
408 cid	Displacement	383 cid
4.030	Bore size	4.030
4.000	Stroke	3.75
FAST XFI electronic fuel injection	Fuel system	Holley 750-cfm carburetor
560 at 5,800 rpm	Horsepower	554 at 6,300 rpm
557 at 4,600 rpm	Torque	536 at 4,500 rpm
$12,941.26	Cost (as shown	$9,698.80