The debate between LS and HEMI engines is a cornerstone of the automotive performance world. Enthusiasts often pit these two architectures against each other when planning a high-horsepower build, weighing factors like cost, parts availability, power potential, and overall character. Both platforms can reliably achieve 550 horsepower with the right combination of components, but the path and price tag differ. This article provides a detailed, itemized cost breakdown for building a 550 hp LS engine using Trick Flow parts versus a 550 hp HEMI engine using Mopar Performance parts, along with insights into why each component matters and how it affects your budget.

Overview of the LS and HEMI Architectures

General Motors’ LS engine family, introduced in 1997, revolutionized the aftermarket with its lightweight aluminum or iron block, simple pushrod design, and robust factory internals. Its widespread adoption means parts are plentiful and relatively affordable. The LS thrives on cylinder head flow and camshaft timing, making Trick Flow’s high-flowing heads and matched components a natural fit for a 550 hp target.

Chrysler’s HEMI engine, particularly the third-generation 5.7L, 6.1L, and 6.4L variants, features a hemispherical combustion chamber design that offers exceptional flame propagation and power density. Mopar Performance supplies OEM-grade parts engineered for durability and output. While the HEMI is heavier and often more expensive to build than the LS, it delivers a distinct powerband and sound that many Mopar loyalists prize.

Reaching 550 hp requires careful selection of parts that work in harmony. Below we examine each engine build component by component, with pricing based on current market averages from reputable sources like Summit Racing and JEGS.

Building a 550 HP LS with Trick Flow Parts

Engine Block

For 550 hp, an LS iron block (6.0L LQ4/LQ9 or 5.3L with an appropriate stroker kit) is a cost-effective choice. A used, machined iron block running 4.000–4.030-inch bore will cost around $1,500 after inspection, hot-tank, and honing. Aluminum blocks (LS3/LS7) are lighter but push the budget higher. Estimated cost: $1,500

Forged Crankshaft

A forged 4340 steel crankshaft with a 3.622-inch stroke (stock LS1 length) is strong enough for 550 hp and beyond. Many builders opt for a Callies or Eagle unit. Estimated cost: $800

Forged Pistons

Forged aluminum pistons (often Mahle or Wiseco) with a dish to maintain a 9.5:1–10.0:1 compression ratio work well with Trick Flow heads and a moderate cam. Estimated cost: $600 (set of eight with pins and rings).

Connecting Rods

Forged H-beam rods (6.125-inch length for LS builds) provide ample strength. Estimated cost: $700 (set of eight).

Trick Flow Cylinder Heads

Trick Flow’s 225cc or 255cc LS heads flow over 300 cfm out of the box, supporting 550 hp with ease. They come assembled with CNC chambers, Manley valves, and dual springs suitable for a mild cam. This is the single largest expense in the build. Estimated cost: $2,200 (pair, assembled).

Intake Manifold

A high-rise single-plane intake like the Trick Flow LS Street Burner or a suitable LS6/LS3 manifold works well. Estimated cost: $400

Camshaft

A hydraulic roller cam with around 230–235 degrees duration at .050-inch and .600+.600 lift is typical for 550 hp. Estimated cost: $350 (billet or core with lifter set).

Fuel Injectors

High-impedance 45–60 lb/hr injectors handle 550 hp on gasoline. Estimated cost: $300 (set of eight).

Exhaust Headers

Long-tube headers with 1.875-inch primary tubes are critical for scavenging. Estimated cost: $500 (mild steel coated or stainless).

Engine Management System

A stand-alone harness and ECU (Holley Terminator X or similar) provide tuning flexibility. Estimated cost: $1,000 (harness, ECU, sensors).

Total LS Estimated Cost: $8,450

This total covers the rotating assembly, heads, cam, intake, fuel, headers, and engine management. It does not include labor, machining, gaskets, fasteners, cooling, or accessories. Most engine builders will add another $1,500–$2,000 for assembly and machining, bringing the total to around $10,000–$10,500 for a ready-to-run long-block.

Building a 550 HP HEMI with Mopar Performance Parts

Engine Block

The HEMI block (from a 6.1L or 6.4L SRT) is heavier and more expensive. A used iron block machined for forged components costs around $1,800. Aluminum HEMI blocks exist but are rare and costly. Estimated cost: $1,800

Forged Crankshaft

A 4340 stroker crank (4.050-inch stroke for 392 cubes) is common for 550 hp builds. Estimated cost: $900

Forged Pistons

Forged pistons with a dish for about 10.0:1 compression support 550 hp on pump gas. Estimated cost: $700

Connecting Rods

Forged H-beam rods rated for 700+ hp. Estimated cost: $750

Mopar Performance Cylinder Heads

Mopar offers cast aluminum cylinder heads with 270+ cfm flow out of the box. These heads are CNC-ported and optimized for the HEMI combustion chamber. Estimated cost: $2,500 (pair, assembled).

Intake Manifold

A Mopar Performance single-plane or high-rise dual-plane intake suits this power level. Estimated cost: $450

Camshaft

A hydraulic roller cam with 230–236 degrees duration at .050-inch and .600+.600 lift is typical. Mopar Performance offers grinds specifically designed for their heads. Estimated cost: $400

Fuel Injectors

50–60 lb/hr injectors handle 550 hp. Estimated cost: $350

Exhaust Headers

Long-tube headers for the HEMI (1.875-inch primary) are slightly more expensive due to tighter chassis clearance and lower production volume. Estimated cost: $600

Engine Management System

A Holley Terminator X or a Mopar-specific ECU (like the factory PCM reflashed) works. The stand-alone option costs about $1,200. Estimated cost: $1,200

Total HEMI Estimated Cost: $9,350

Again, this excludes machining and assembly labor. With those added, a long-block HEMI may approach $11,500–$12,000.

Direct Cost Comparison

Component LS (Trick Flow) HEMI (Mopar Performance)
Engine Block$1,500$1,800
Forged Crankshaft$800$900
Forged Pistons$600$700
Connecting Rods$700$750
Cylinder Heads$2,200$2,500
Intake Manifold$400$450
Camshaft$350$400
Fuel Injectors$300$350
Exhaust Headers$500$600
Engine Management$1,000$1,200
Total$8,450$9,350

The LS build comes in roughly $900 less than the HEMI build. The difference stems from higher base block costs, premium Mopar cylinder heads, and slightly more expensive management systems.

Performance and Reliability Considerations

Cost is not the only factor. The LS’s lighter weight (by about 80–100 lbs) benefits handling and acceleration in many platforms. The HEMI’s heavier rotating assembly and unique combustion chamber can produce higher torque at lower RPM, which may suit street-driven cars better.

Both builds require careful attention to the cooling system, oiling modifications (especially on HEMIs with timing chain issues), and professional tuning. Trick Flow heads are known for excellent mid-lift flow, while Mopar Performance parts are engineered to tight OEM tolerances. Forged internals in both builds will happily handle 550 hp with frequent use if properly maintained.

Which Engine Should You Choose?

Budget-Conscious Builders

The LS platform offers the lowest entry cost and the widest aftermarket support. Trick Flow provides proven components that have powered countless LS builds to 550 hp and beyond. If your project car is a Fox-body Mustang, a third-gen F-body, or a classic Chevy, the LS is the logical choice.

Mopar Enthusiasts

If you are building an older Chrysler, Dodge, or Plymouth—or you simply want the sound and heritage of a HEMI—the Mopar Performance route delivers an authentic experience. Mopar Performance parts are backed by the factory and designed for street/strip reliability. Expect to pay a premium for that legacy.

Aftermarket Support and Future Upgrades

The LS ecosystem supports easy upgrades to 600+ hp with only a cam and head swap. The HEMI, while capable, often requires swapping the intake or headers for additional gains, and parts availability can be more limited. For long-term budget planning, the LS offers a cheaper path to higher power levels.

Final Thoughts

Both the LS and HEMI engines can produce a reliable 550 hp. The LS build using Trick Flow parts is approximately 10% cheaper in component costs compared to the HEMI build with Mopar Performance parts. However, the choice goes beyond dollars and cents. Consider the vehicle it will live in, your commitment to a particular brand, and the availability of skilled tuners in your area. For a detailed look at LS vs. HEMI head flow numbers and dyno data, check out this Hot Rod LS build guide and this MotorTrend HEMI build article.

No matter which path you choose, investing in quality parts from trusted manufacturers like Trick Flow and Mopar Performance ensures you get the performance you pay for. Your final expense will depend on every decision from engine mounts to exhaust tips—but with the numbers above, you now have a clear baseline for your 550 hp project.