What is a Stroker Engine | Stroker Motor Chart for Chevy, Ford, and Mopar
What is a Stroker Engine?
There is an old saying in the hot rod community that usually goes something like, “There’s no replacement for displacement.” Larger displacement engines can make more power. One of the oldest ways of increasing the size of an engine is by altering the stroke, creating a “stroker motor.”
How Do You Stroke an Engine?
At the most basic level, stroking an engine is accomplished by altering the distance the piston travels in the cylinder, called stroke, with a stroker crankshaft. What is a stroker crankshaft? Replacing the crankshaft allows the engine to have a longer stroke. The stroke of a crankshaft is defined as the total distance a piston travels within the cylinder bore of an engine. This travel, from bottom dead center (BDC) to top dead center (TDC) is based upon the measurement from the crankshaft’s pin offset centerline to the crankshaft’s main journal centerline multiplied by two. A higher distance value indicates a longer stroke.
Stroking an engine increases the side load on the rotating assembly. The crankshaft can’t fully rotate with the connecting rod at a certain point without contacting the engine block. Machining is usually necessary to provide adequate clearance of the rotating assembly. This is often accomplished by hand with a carbide cutter or other cutting tool. Additionally, increasing the diameter of the piston adds to displacement. The bore defines the diameter of the cylinder that fits the piston. Bore and stroke work in tandem to optimize the performance of an engine.
A stroker motor increases the distance the piston moves during the cycle. The result of stroking is a larger volume of air and fuel drawn into the cylinder. The amount of air the cylinders can hold is known as displacement. Measurements describing displacement are cubic inches, cubic centimeters, or liters.
The amount of force the piston exerts on the air/ fuel mixture is called the compression ratio. Different piston designs alter the amount of compression. Higher compression pistons create more power but require higher octane fuel and more durable parts to withstand the added stress. Stroke, bore, displacement, and compression interrelate and are fundamental to building a high-performance motor. Speedway Motors has a handy engine displacement calculator that shows engine size with various bore and stroke combinations to help nail down which displacement works best for your project.
Stroker Engine Pros and Cons
There are advantages and disadvantages to building a stroker motor. Here are some facts to consider.
Pros
- Increased power and performance
- Tailored powerband for specific applications
- Retains the factory appearance
- Improves low-end torque
Cons
- Can reduce reliability
- Burns more fuel
- It can be expensive to build
- Often requires other modifications, such as upgrades to the braking system
- It may decrease the value of some classic cars
What is a Stroker Crankshaft?
A stroker crankshaft increases the throw of the connecting rod. Stroker crankshaft designs take advantage of the maximum distance available within the cylinder. Machining the block in several places provides clearance for a stroker crankshaft. Additional machine work on the crankshaft allows a different crankshaft to work in an engine block. The key areas to modify are the main bearing journals and the connecting rod journals.
In some cases, a factory crankshaft from one engine can be fitted to a different engine block to increase or decrease the stroke. A fun fact is that nearly every factory engine is technically a stroker. The small block Chevy displacing 350 cubic inches started as a 265ci engine. Similarly, the small block Ford 302 started as a 221ci engine. The factory engineers simply changed the bore and stroke to create larger displacements. Dozens of different displacements are possible, but a handful are the most common. The easiest way to build a stroker is to use a kit that includes matched connecting rods, pistons, and the proper crankshaft. Explore stroker engine kits under our rotating assemblies to find the ideal kit for your next build.
A Note on De-Stroking De-stroking an engine is typically done to take advantage of characteristics or to meet displacement rules in racing. When an engine is de-stroked, it will attain higher RPMs faster and will be capable of reaching higher RPMs. This is most desirable for configurations that spend most of the time at wide-open throttle, such as endurance racing and drag racing. The downside of a de-stroked engine is a loss of low-end torque. Reducing the weight of a vehicle can offset the loss of low-RPM power.
Stroker Engine Combinations Chart
Download a copy of our stroker combinations chart for personal use or to share with friends!
Small-Block Chevy Stroker Engine Combinations
The small-block Chevy engine is the most mass-produced engine for several reasons. This engine can develop tremendous power, aftermarket parts are plentiful and inexpensive, and aftermarket companies have designed motor mounts to adapt the engine to nearly any vehicle. The most common build is the legendary Chevy 383 stroker. This stroker engine produces lots of low-end power and has excellent street manners. There are several ways to achieve the proper displacement. The “old-school” way was to use the crankshaft from a 400-small block with the main journals turned down to fit the 350-engine block. Today, aftermarket crankshafts are increasingly popular and are included in 383 stroker kits.
Variations of the small-block Chevrolet engine include factory 305ci, 350ci, and 400ci displacements. While it is possible to stroke a 305, this modification is generally frowned upon due to the limitations of the factory casting. Aftermarket crankshafts are available to build any number of different displacement engines. Be careful when selecting a camshaft for a stroker motor with a 350 engine block. Many designs will create interference between the rods and the cam.
A rare option for stroking the 400ci Chevy small block involves using a 350ci crank in the 400ci block. Known as a de-stroked engine, these are most common in racing applications. The combination produces an engine displacing 377ci that can hit higher rpm. The 400ci small block can use aftermarket crankshafts to displace up to 433ci.
Aftermarket SBC Engine (Raised Deck and Raised Cam)
Aftermarket companies now produce brand-new engine blocks with innovative features. The major difference is the location of the camshaft in the block. The raised cam design eliminates one of the key obstacles to building bigger stroker motors from small-block Chevrolet engines. Aftermarket 350ci and 400ci small-block engines are available in various deck heights to maximize stroke. Big block engines are also available with raised deck designs and can be found in factory form in some Chevrolet trucks.
Big Block Chevy Stroker Engine Combinations
The Chevrolet 454ci big block is a legend. Stroker kits maximize the amount of power this behemoth can produce. Rotating assemblies using a 4.250” stroke results in a 496 big block. Chevrolet made this engine in a tall deck version found in truck applications. Those blocks can use a 4.500” stroke and an overbore to achieve a maximum displacement of 572ci. A Chevy big block 632 version is available as a factory-prepped crate engine.
GM LT & LS Stroker Engine Combinations
General Motors replaced the aging small block design in 1997 with the all-new LS engine. It shares only a few parts with previous engine designs. Advantages of the LT and LS motors include more durable designs, weight-saving aluminum blocks in many applications, and a revision to the firing order to produce smoother operation.
The LT and LS engine series tend to share displacement sizes with the previous generations of small block V8s, but the crankshaft is different. Similar displacements are available for stroking the LT and LS engines. One of the most popular stroker conversions transforms the 7.0L to a 416 stroker.
Small Block Ford Stroker Engine Combinations
The engine of choice for Mustangs, Falcons, and tens of thousands of Ford trucks is the small block Ford in 302 cubic inches of displacement. Plentiful aftermarket parts and easy fitment in tight chassis make this engine one of the most popular to modify. The most common small-block Ford stroker is the 347ci when starting with a 302ci stock block. An aftermarket 347 stroker kit simplifies this build and matches components for durability.
With a taller deck height than the 302, the 351 Windsor shares many design aspects as the Ford 302. A stock 351 Windsor using the longest possible stroke and largest possible bore will yield 427ci, though many Ford enthusiasts will caution to stay with no larger than a 408 stroker using a stock block. Aftermarket “big bore” engine blocks can easily yield a 427ci displacement on up to 454ci.
Ford produced a 351 Cleveland engine that differs from the 351 Windsor. The Cleveland uses a different bell housing bolt pattern, heads, and timing chain cover assembly, among other differences. The Cleveland is a rare engine option, having only four years of production, but stroker kits take the stock displacement to 408 ci.
Big Block Ford Stroker Engine Combinations
The Ford 460ci big block V8 is popular for drag racers, classic trucks, and even speedboats. It can make nearly unlimited horsepower. Many high-performance Ford vehicles feature the big block V8. The big-block Ford can displace 552ci with a 429 stroker kit that includes a stroker crankshaft and matching rotating assembly to build massive low-end power.
The Ford FE-series was the premier performance engine in the mid-to late-1960s. The 390 FE is the most common factory displacement. Factory performance variants are found in a variety of mid-size Ford and Mercury vehicles. Stroker kits for the FE engine series can yield displacements of 445ci for 390 blocks and 455ci for 428 blocks.
Ford Flathead Stroker Engine Combinations
The engine responsible for the hot rod craze is still a popular option today. A fantastic way to get power increases from this antiquated design is a stroker kit. Aftermarket rotating assemblies deliver up to 304ci from the stock 8BA engine or the later 59A block.
Ford Modular Stroker Engine Combinations
Ford replaced the aging 5.0L 302ci pushrod V8 with an all-new design commonly known as the Modular engine displacing 4.6L (281ci). This engine takes advantage of single or dual-overhead cams with two, three, or four valves per cylinder, and can produce tremendous power. Stroker assemblies are available to stretch the 4.6L out to a 5.0L/5.1L of displacement.
Mopar Small Block Stroker Engine Combinations
Some of the most brutal street machines ever built rolled off the assembly lines at Dodge and Chrysler factories in the late 1960s. Many use variations of the company's unique small block engines displacing 318ci, 340ci, or 360ci. Aftermarket rotating assemblies can produce displacements up to 408 ci while providing excellent street manners.
Later 5.2L Magnum engines use many of the same components as the earlier engines. Aftermarket rotating assemblies can provide as much as 396ci displacements from the stock 5.2L engine. Even more displacement can come from the 5.9L Magnum engines. A Mopar 408 stroker crate motor is available to quickly add massive horsepower and torque to any project.
Mopar Big Block Stroker Engine Combinations
The Mopar big block originally displaced anywhere from 383ci up to 440ci. The most famous of them all was the 426 “Hemi” often referred to as the Elephant. Aftermarket parts are available to generate tremendous amounts of torque from these monster engines. The 383ci can gain as much as 113 cubes with a proper bore and stroke combination to build an engine displacing 496ci. The mid-size 400ci big block can displace an astonishing 512ci with the proper combination of parts. When it comes to all-out size, few engines will beat the 440ci stroked to a displacement of 543ci.
Gen III Hemi Stroker Engine Combinations
When Mopar replaced its aging V8 lineup in 2003, they jumpstarted a horsepower war that had laid dormant for decades. Starting with the 5.7L Hemi, variations of the Gen III engine grew to include the Hellcat and Demon engines that produce over 800 horsepower from the factory. Stroking these engines can make gobs of power and performance.
The early 5.7L engine can handle aftermarket rotating assemblies that displace 6.5L. The 6.1L engine has kits to increase displacement to 7.0L. Mopar’s infamous “392” engine displaces 6.4L in factory trim but grows to 427ci of displacement with aftermarket rotating assemblies. The “Hellcat” motor is already a beast, but a stroker kit can unleash even more power by increasing displacement up to 426ci.
Jeep Stroker Engine Combinations
The Jeep 4.0L is a straight-six design regarded as one of the most durable engines ever produced. Stroking this engine makes a powerplant ideal for off-road shenanigans. This is a popular modification that can be made with factory parts. The Jeep 4.0 stroker engine uses the crankshaft and connecting rods from a 4.2L AMC straight-six, an aftermarket camshaft, and fuel injectors from a 4.0L High Output engine. With a 0.030-inch overbore, the engine displaces 4.7L.
Stroker Engine Supporting Performance Parts
While we explained earlier under “What Is a Stroker Engine?” just what defines such an engine, building a stroker engine isn’t just about the rotating assembly and it’s longer stroke. With increased displacement comes the need for increased airflow (intake, camshaft, and cylinder heads). This means thinking above the traditional airflow needs of the base engine.
The ultimate limitation of any engine, including stroker motors, is the efficiency of the cylinder heads. A head can supply only a specific amount of air and fuel. No amount of displacement increase will alter how well the head flows. Larger intake runners and larger valves can increase the flow of the head to improve performance. A cylinder head upgrade should be part of any stroker engine build. Modern aftermarket aluminum cylinder heads offer significant performance improvements and save lots of weight.
Along with upgrading the heads, builders should upgrade the intake manifold and carburetor. A high-rise or mid-rise dual-plane design works great for street engines. Tunnel ram designs work best on the drag strip. A performance intake manifold is essential to realize the true potential of a stroker engine and is one of the first add-ons most builders make. No amount of flow improvement or displacement can make more power without adding more fuel. Today’s four-barrel carburetors are significantly better than older factory designs and are essential for getting the proper air and fuel mixture to the cylinders.
Let’s say a traditional small block Chevy uses a 170cc cylinder head, .480 lift cam, and a dual plane intake for street performance. Taking that 350 out to a 383ci stroker means that those heads, camshaft, and intake will not be able to support the higher airflow needs of that stroker engine now. So, adding a stroker kit to your 350 Chevy means it now will need more airflow via larger induction pieces. Something along the lines of a 200-220cc cylinder head, .580-.600 lift cam, and some sort of mid-rise single plane intake will support the extra cubic inches appropriately. Think of the airflow needs as a whole and purchase your supporting components to complement the larger displacement. This goes for your headers and exhaust tubing diameter as well.
Machining Considerations for Building a Stroker
Building a stroker motor is more complex than just ordering some parts and bolting them together. A significant amount of machine work and careful testing of various clearances is required. This part of the build is the most important because an error in the machining can cause a total engine failure.
While some builders have the tools and expertise to machine engines in their home garage, this is usually a step best left to a professional machine shop. A shop will ensure that the block and crank are free of defects and cracks, cylinder head mounting surfaces are perfectly flat and properly aligned, and crankshaft and camshaft bores are aligned and sized correctly for bearings. A machine shop or an engine builder will check the crankshaft and connecting rod bearing clearances, ensure consistent cylinder bore, and verify the overall fit of parts before assembling the engine.
Blueprinting refers to documenting the various measurements throughout the build. Blueprinting is time-consuming to accomplish but is vital to ensuring a proper build. Balancing the rotating assembly is an absolute must when building a stroker motor, so don’t skip that step.
Three Ways to Build a Stroker Motor
There are three ways to build a stroker motor for your project. The simplest and often least expensive method is purchasing a stroker crate motor. Stroker crate motors use matching parts and are pre-tested to ensure power output and reliability. Many crate engines we offer are stroker engines and many today even come with a factory warranty.
The second way to build a stroker motor is to use a kit. The kit features matching parts that require minimal machine work. This method is the best way to go when building less common stroker displacements. Kits are available for numerous engine sizes and can be found under our rotating assemblies.
The final way is to select individual components found within our cylinder block components section. This method can use factory performance parts, aftermarhttps://static.speedwaymotors.com/images/seven_18May16.jpgket components, and unique combinations to build a custom stroker motor. It is often the most expensive and difficult route and requires significant machining.
