The 5.7-liter Hemi V8 is one of the most popular and versatile platforms in modern performance. Its hemispherical combustion chambers, large bore spacing, and robust iron or aluminum block architecture give it a solid foundation for serious power. While the engine is strong out of the box, pushing beyond 700 horsepower demands a disciplined approach to component selection and engine building. This guide covers the best connecting rods, pistons, and every supporting modification needed to make that power live on the street or the strip.

Understanding the 5.7 Hemi Foundation

The 5.7 Hemi was introduced in 2003 and evolved through several generations. Early engines use a cast-iron block; later models (2009+) feature an aluminum block in many applications. Both blocks share the same basic architecture: a 3.58-inch stroke, 3.917-inch bore, and a 6.200-inch connecting rod length. The stock forged powdered-metal rods and cast hypereutectic pistons are fine up to about 500–550 horsepower. Beyond that, the bottom end becomes the primary weak point. The factory rod bolts stretch, the pistons crack under detonation, and the ring gaps close under high cylinder pressure. To reach 700+ horsepower reliably, every component in the rotating assembly must be upgraded.

Forging the Bottom End: Rods and Pistons

Connecting Rods

The rod is the critical link between the piston and the crank. At 700+ horsepower, peak cylinder pressures can exceed 2000 psi, and the rod must handle that force without bending or breaking. The stock rod beams are adequate for moderate boost, but aftermarket forged rods offer superior material, design, and fastener quality.

  • Manley H-Beam Connecting Rods – Made from 4340 chromoly steel, shot-peened, and offered with ARP 2000 or L19 fasteners. The H-beam design resists buckling under high compressive loads, making it ideal for supercharged and turbocharged builds. Manley rods require minimal clearancing in most 5.7 blocks.
  • Wiseco HD Pro Series Rods – Forged from 4330M premium steel, these rods come fully profiled and balanced. They feature a large pin bore for thicker wrist pins and are available in standard 6.200-inch or custom lengths. Wiseco’s precision machining reduces reciprocating weight while maintaining strength.
  • Callies Compstar Rods – A popular choice for high-rpm and forced-induction applications. The Compstar uses a specially formulated 4340 steel and is center-counterweighted for improved balance. The rod’s small end is bushed for proper pin oiling, and the big end accepts standard bearing shells.
  • K1 Technologies H-Beam Rods – Also 4340, these rods are a budget-friendly alternative that still meets the demands of 700+ HP. They include ARP bolts and are balanced in sets of eight. Many builders use K1 rods successfully in 800–900 HP turbo builds.

Pistons

Pistons must seal combustion pressure, dissipate heat, and withstand repeated thermal and mechanical shock. For 700+ horsepower, cast or hypereutectic pistons will fail. Forged pistons expand more, requiring tighter cold clearance, but they hold up to detonation far better.

  • Diamond Racing Pistons – Custom-manufactured to your specific bore, compression height, and valve reliefs. Diamond uses 2618 aluminum alloy, which is softer and more impact-resistant. Their offset wrist pin design reduces piston slap and noise. For boosted 5.7 applications, specify a thick ring pack and drilled oil rings.
  • JE Pistons – Available off the shelf in various compression ratios (9.0:1, 9.5:1, 10.5:1) for both naturally aspirated and forced induction. JE’s FSR (Fully Skirted Racing) design improves ring seal and reduces wear. Their proprietary thermal coating on the crown lowers head temperatures.
  • CP-Carrillo Pistons – Known for tight tolerances and high-strength 2618 forgings. CP offers a broad range of 5.7 Hemi pistons with specific ring packages for nitrous or boost. Their symmetrical dome and valve pocket design allow for large cam profiles without interference.
  • Mahle PowerPak Pistons – While less common in the Hemi world, Mahle’s 4032 alloy pistons offer lower expansion and better cold-start clearance than 2618. They are a good choice for street-driven 700+ HP builds where long life and low noise matter.

Ring gaps become critical at this power level. For a 700+ HP boosted 5.7, set the top ring gap to 0.024–0.028 inches and the second gap to 0.030–0.035 inches. Always measure and file rings individually to the cylinder bore. Use a strong aftermarket wrist pin—0.927-inch diameter is standard, but a larger 0.990-inch pin (with a proper bushing in the rod) provides extra safety margin for 900+ HP.

Rotating Assembly Balancing

Internal balancing is essential. The stock 5.7 crank is externally balanced with a heavy harmonic balancer and flexplate. Aftermarket rods and pistons shift the weight distribution. Have the entire assembly—crank, rods, pistons, pins, rings, and harmonic balancer—professionally balanced to within 0.5 grams. This reduces bearing loads and prevents crank flex at high RPM.

Block Preparation and Main Studs

The 5.7 block itself is stout, but the main bearing caps can walk under high cylinder pressure. Install ARP main studs to replace the factory bolts. Studs maintain consistent clamp load and prevent cap shifting. For aluminum blocks, helicoils or Timeserts in the main bolt holes are recommended if the threads are marginal. Also consider a billet main cap girdle (available from companies like Billet Industries) that ties all five caps together. This addition is particularly important for stroker builds that exceed 4.00 inches of stroke.

Deck the block to ensure a flat surface for the head gaskets. Aim for a finished deck height that gives a piston-to-head clearance of 0.035–0.045 inches for boosted engines. Use a torque plate when honing the cylinders to simulate the distortion caused by head bolt torque. Final hone crosshatch angle should be 45–50 degrees, with a finish RA of 15–20 microinches for moly rings.

Valvetrain and Cylinder Heads

Camshaft Selection

A 700+ HP 5.7 needs a camshaft that supports the power band. For forced induction, a wide lobe separation (114–116 degrees) reduces overlap and keeps boost from blowing through the cylinder. Duration should be in the mid-220s to low-240s at 0.050-inch lift. Street/strip builds with a turbo can use a 226/232 on a 115+2 LSA. For a supercharger, a slightly shorter duration helps maintain low-end torque. Lift should be at least 0.600–0.650 inches; pair with a high-lift rocker arm (1.7 or 1.8 ratio) to open the valves fully.

  • Comp Cams offers several grinds specifically for the 5.7 Hemi with boost.
  • Hughes Engines sells custom-grind camshafts for 700+ HP builds using their proprietary lobe profiles.
  • Lifters: Use a billet or solid roller lifter for reliability. The factory hydraulic roller lifters pump up at high RPM. Upgrading to a morel or Johnson roller lifter with a limited travel or solid design is recommended.
  • Valve Springs: Dual or beehive springs with 200 pounds of seat pressure and 550–600 pounds open pressure are needed for aggressive lobes and high boost levels. Replace spring retainers with titanium or heavy-duty steel units.

Cylinder Head Upgrades

The stock Eagle or Apache heads (depending on year) flow decently but choke above 550 HP. For 700+ horsepower, port the heads for higher flow, especially on the exhaust side. A good CNC port job on a set of Eagle heads can push flow past 280 cfm intake and 190 cfm exhaust at 0.600-inch lift. Install larger valves: 2.00-inch intake and 1.55-inch exhaust are standard for most builds. Consider a thicker head gasket (0.060–0.080 inches) to lower compression if running high boost. Use high-quality MLS gaskets with a steel fire ring. Head studs from ARP are mandatory; use 11mm studs with a fine thread for consistent clamp load.

Induction and Exhaust

Intake Manifold and Throttle Body

The factory intake manifold restricts high-rpm airflow. Replace it with a dual-plane or single-plane aftermarket manifold. For forced induction, a low-profile intake that fits under a stock hood is common, but larger intake plenums allow more air volume. Indee Fab makes a sheetmetal intake for the 5.7 that supports 1000+ HP. Match the throttle body to the power level: a 90mm or 105mm unit is typical for 700+ HP. Ensure the intake tube diameter matches the compressor outlet for turbo setups.

Exhaust

Headers are one of the easiest power gains. Long-tube headers with 1⅞- or 2-inch primaries and a 3-inch collector improve exhaust scavenging. For boosted engines, larger primary tubes (2 inches) reduce backpressure and spool turbos faster. Use stainless steel headers to resist corrosion. Pair them with a full 3-inch or 3.5-inch exhaust system. Avoid restrictive mufflers; a good turbo-style or straight-through design works best.

Fuel System Requirements for 700+ HP

Fuel delivery is non-negotiable. The stock fuel pump and injectors can handle around 500 HP. For 700+ HP, you need:

  • Fuel Pump: An in-tank 340–450 LPH pump (e.g., Walbro 450 or DeatschWerks DW400) for pump gas. For E85, step up to a 525 LPH pump or a dual-pump setup.
  • Injectors: 1000–1200 cc/min at 43.5 psi for gasoline; 1300–1600 cc/min for E85. Use high-impedance injectors compatible with the ECU.
  • Fuel Lines: -8 AN feed and -6 AN return minimum for gasoline; -10 AN feed for E85.
  • Regulator: A boost-referenced return-style regulator maintains constant differential pressure.
  • Fuel Rail: Stock rails can feed 700 HP, but aftermarket billet rails with larger passages offer better distribution on high-boost builds.

E85 Tuning: If you plan to run E85, increase injector size by 30% and use stainless steel lines to avoid corrosion. Tune for a lambda of 0.75–0.78 at full throttle.

Engine Management and Tuning

The factory ECU (PCM) can be tuned for 700+ HP with custom software like HP Tuners or DiabloSport. However, the stock knock sensors and fuel trims can limit power. For a dedicated race build, a standalone ECU (Holley Dominator, MoTeC, or AEM Infinity) gives full control over timing, fuel, and boost. Tuning is the most critical supporting mod—no combination of parts will perform well without a proper air/fuel and spark map. Find a reputable dyno tuner who has experience with the 5.7 Hemi. Expect 700–750 whp on pump gas with good boost control; E85 can push that to 800+ whp safely.

Supporting Systems: Cooling, Oiling, and Drivetrain

Oil System

The stock oil pump is marginal for sustained high RPM. Upgrade to a high-volume, high-pressure oil pump (e.g., Melling M295 or a custom Billet pump). An oil pan with windage tray and crank scraper prevents oil starvation during hard acceleration. For road racing or long pulls, install an oil cooler with a thermostat.

Cooling System

700+ HP generates a lot of heat. Upgrade to a larger aluminum radiator (two- or three-row) with electric fans. Use a lower-temperature thermostat (160°F) and a water pump spacer to increase coolant velocity. For supercharged builds, an intercooler or a heat exchanger with a separate pump and reservoir is necessary.

Drivetrain

The stock 5.7 transmission (NAG1 eight-speed or older W5A580) will not survive 700+ HP for long. A built 8HP70 or a manual swap (T56 Magnum or TR-6060) is the best solution. Upgrade the torque converter to a multi-disc billet unit with a higher stall speed (3200–3600 rpm for street/strip). The rear differential must be upgraded: a Dana 60 or GM 14-bolt swap is common, or at least a Ford 9-inch with 35-spline axles. Use a limited-slip or spool differential.

Conclusion

Reaching 700+ horsepower with a 5.7 Hemi is not a parts-throwing exercise. It requires a systematic approach: select forged rods and pistons with the right ring gaps, prepare the block with studs and accurate honing, upgrade the valvetrain and cylinder heads, match the fuel system to the power level, and tune meticulously. The supporting modifications—enhanced oiling, cooling, and drivetrain—are just as important as the go-fast parts. By following the specifications outlined here and sourcing quality components from trusted brands, you can build a 5.7 Hemi that delivers reliable, high-horsepower performance for seasons to come.