Building a 400+ HP 5.7 Hemi: The Complete Guide

The 5.7-liter Hemi V8 is one of the most popular and accessible engines for performance builds. With its hemispherical combustion chambers and robust bottom end, this engine responds exceptionally well to bolt-ons and forced induction. While a stock 5.7 Hemi produces between 340 and 395 horsepower depending on the vehicle and year, reaching 400+ wheel horsepower is entirely achievable with a carefully planned combination of parts. This guide covers the essential upgrades—camshaft, headers, and forced induction—along with the supporting mods and tuning required to make serious power safely.

Understanding the 5.7 Hemi Platform

First introduced in 2003 for Dodge Ram trucks, the 5.7 Hemi quickly found its way into Chargers, Challengers, Magnums, and Chrysler 300s. The engine underwent a major update in 2009 with the introduction of the Eagle version, which included variable valve timing (VVT), improved cylinder heads, and a forged steel crankshaft. Pre-2009 engines (non-Eagle) lack VVT and use a cast iron crank but are still excellent candidates for upgrades. The key limitations on any 5.7 Hemi are the cast pistons and powdered metal connecting rods, which become a concern past 500–550 horsepower at the crank. For a 400+ wheel horsepower build, the stock rotating assembly is generally fine with a safe tune.

Another factor to consider is the Multi-Displacement System (MDS) found on many 5.7 Hemis. MDS deactivates four cylinders under light load for fuel economy. When building a performance engine, many enthusiasts choose to delete MDS and replace the lifters with standard non-MDS units, as the MDS lifters can be a failure point at higher rpm or with aggressive camshafts.

Camshaft: The Heart of the Build

A proper performance camshaft is often the single biggest power adder on a naturally aspirated 5.7 Hemi. Swapping the cam changes valve timing, lift, and duration to let the engine flow more air and make power higher in the rpm range. However, a cam swap is not a simple drop-in job; it requires removing the timing cover, radiator, and often the cylinder heads to replace valve springs. Plan for a full weekend or professional labor.

Choosing a Camshaft Profile

Camshafts are typically categorized by stage, which indicates aggressiveness. For 400+ horsepower at the wheels, a Stage 2 or mild Stage 3 cam is ideal. Key specs to consider:

  • Duration – Measured at 0.050-inch lift. For 400+ hp, look for 220–240 degrees intake duration. Longer duration shifts the powerband higher but sacrifices low-end torque.
  • Lift – Around 0.550–0.600 inches is common. Higher lift requires stronger valve springs and may need piston-to-valve clearance checks.
  • Lobe Separation Angle (LSA) – 112–114 degrees is a good middle ground, giving a broad powerband and somewhat streetable idle. A tighter LSA (110) produces a choppier idle and more top-end but can be harder to tune.
  • VVT vs Non-VVT – 2009+ Eagle engines have VVT, meaning you need a cam that works with the variable camshaft phaser, or you can delete VVT and use a non-VVT cam with a suitable phaser lockout and tune. Many builders choose to delete VVT for simplicity and cost savings.

Popular cam choices include units from Comp Cams, Brawler, and custom grinders. Be prepared to replace valve springs, retainers, and pushrods with your cam to handle the higher lift and rpm.

Supporting Components for a Cam Swap

When you upgrade the cam, you must also upgrade the valvetrain. Stock valve springs will likely bind or float at high rpm. Install a set of dual or beehive springs rated for your cam’s lift. Long-tube headers are highly recommended to complement the cam’s increased flow capacity. A custom tune is mandatory after a cam swap—the engine will not run properly on the factory calibration. You'll also need to consider the fuel injectors; stock 28 lb/hr injectors may be insufficient if you exceed about 420 hp at the crank.

Exhaust Headers: Freeing the Flow

Headers are one of the best bolt-on upgrades for the 5.7 Hemi. By replacing the restrictive factory exhaust manifolds, headers allow exhaust gases to exit quickly, reducing backpressure and scavenging more air out of the cylinders. This directly translates to power gains of 15–30 horsepower at the wheels, often with a simple tune.

Long Tube vs. Shorty vs. Mid-Length

  • Long tube headers provide the biggest power gains (20–30 hp on a cammed Hemi). They move the collector further downstream, which improves exhaust scavenging at higher rpm. However, installation is more complex, requiring removal of the steering shaft on some cars and sometimes modifying the mid-pipe. They may also interfere with ground clearance on lowered vehicles or 4x4 trucks.
  • Shorty headers bolt directly to the cylinder head and are much easier to install. They offer modest gains (5–10 hp) but are better than factory manifolds and compatible with stock exhaust systems. They are a good choice if you want a quick gain without major surgery.
  • Mid-length headers are a compromise between long tubes and shorties. They offer decent flow improvements and easier installation than long tubes, but are less common for the 5.7 Hemi.

Choose headers made from stainless steel for longevity, especially if you drive in winter salt. Brands like Kooks, American Racing Headers, and JBA Performance are well-regarded. Consider ceramic coating to reduce underhood temperatures.

Forced Induction: Supercharging and Turbocharging

If naturally aspirated power isn't enough, forced induction is the fastest way to 400+ horsepower. A 5.7 Hemi with a cam and headers can make around 380–420 wheel horsepower (depending on dyno and fuel). Adding boost can push that number well over 500 hp, but for a 400+ goal, a mild boost setup on a cammed engine is very reliable.

Superchargers

Superchargers are popular because they provide instant throttle response and linear power. The two main types used on the 5.7 Hemi are centrifugal (like a ProCharger) and positive displacement (like a Whipple or Magnuson).

  • Centrifugal superchargers act like a belt-driven turbo, building boost with engine speed. They are relatively easy to intercool and produce great top-end power. Kits from ProCharger and Vortech are available for many Hemi applications, and some can be installed without removing the intake manifold.
  • Positive displacement (roots/twin-screw) superchargers sit on top of the engine and provide immediate boost at low rpm, giving excellent street manners and strong torque. They require a dedicated intake manifold and often a hood clearance modification. Whipple and Magnuson are the leaders here. These kits can be more expensive but deliver a very drivable power curve.

Turbochargers

Turbocharging a 5.7 Hemi is more complex but offers the highest power potential for a given boost level. A single large turbo or a twin-turbo setup can produce massive numbers, but the plumbing and heat management are intensive. For a 400+ hp goal, a single turbo in the 67–76mm range on moderate boost (6–8 psi) is sufficient. Turbo kits are available from companies like Hellion Power Systems and On3 Performance for various chassis.

Key Considerations for Boost

  • Intercooling is non-negotiable. Air-to-air or air-to-water intercoolers prevent detonation by cooling the compressed intake charge. Without an intercooler, you will be limited to very low boost.
  • Fuel system must be upgraded. At 400+ wheel horsepower, you'll need larger injectors (e.g., 60 lb/hr or more) and an upgraded fuel pump (like a Walbro 450 or triple pump setup for higher power).
  • Engine internals – Stock 5.7 Hemis with cast pistons can handle about 450–500 wheel horsepower safely with a good tune and intercooler. Beyond that, forged pistons and rods are required. For 400+ hp, boost level should stay under 8 psi on 91 octane or 10–12 psi on E85 to keep cylinder pressures manageable.
  • Tuning – Boost requires a custom tune from an experienced Hemi tuner. Most use HP Tuners software. A knock sensor failure or lean condition can destroy an engine quickly. Always run a wideband oxygen sensor for monitoring.

Tuning and Supporting Modifications

No build is complete without proper engine management. The 5.7 Hemi ECU can be recalibrated using tools like HP Tuners or DiabloSport. After installing a cam, headers, or boost, a dyno tune is essential to set fuel and spark tables, adjust idle, and calibrate the VVT (if retained).

Fuel System Upgrades

More power demands more fuel. For 400+ wheel horsepower, consider upgrading to at least 36 lb/hr injectors for naturally aspirated builds, or 60 lb/hr for boost. The stock fuel pump can handle up to about 450 crank horsepower on many vehicles, but it’s wise to upgrade to a Walbro 255 or 450 LPH pump, especially if running E85.

Cooling System Upgrades

A 400+ hp engine generates more heat. Upgrade the radiator to a high-flow all-aluminum unit, and consider an oil cooler. On forced induction cars, an intercooler is mandatory. A larger transmission cooler is recommended if your vehicle has an automatic.

Drivetrain Strength

Adding power is pointless if you can’t put it to the ground. On rear-wheel drive cars like Challengers and Chargers, the stock 5-speed or 8-speed automatic transmissions are fairly stout, but the torque converter may need a higher stall speed for aggressive camshafts. On manual cars, the clutch must be upgraded to hold the torque. The stock driveshaft and axles may become weak links, especially on cars with sticky tires. Consider a stronger one-piece driveshaft and upgraded half shafts from DSS or GForce.

Achieving the 400+ HP Goal: A Sample Build

Here's a realistic parts combination for a 2010+ 5.7 Hemi Challenger with variable valve timing, targeting 420–440 wheel horsepower on 93 octane:

  • Camshaft: Stage 2 VVT cam (218/228 duration, .590/.590 lift, 114 LSA) with beefed-up valve springs and pushrods.
  • Headers: 1-7/8” long tube headers with high-flow cats or catless mid-pipes.
  • Intake: Cold air intake and ported throttle body.
  • Exhaust: 3-inch cat-back system.
  • Fuel: 36 lb/hr injectors and a 255 LPH fuel pump.
  • Tuning: HP Tuners custom tune with VVT phaser mapping.

This combination should produce around 420–430 whp, with a fantastic streetable powerband. Add a 100-shot of nitrous for occasional track fun, and you'll be well into the 500s, but that requires additional safety measures.

Common Pitfalls and How to Avoid Them

  • Ignoring the tune. Installing a cam or boost without a proper tune will likely cause engine damage. Always invest in dyno tuning.
  • Overlooking valvetrain strength. Stock springs will not handle aggressive cams. Valve float leads to bent valves and piston contact.
  • Inadequate fuel system. Running lean is fatal. Always verify fuel pressure and injector duty cycle during tuning.
  • Neglecting drivetrain. A 400+ hp Hemi can break stock axles and clutches. Plan upgrades as part of the budget.
  • Using track-only parts daily. An aggressive cam with 240+ degrees of duration may have a choppy idle and poor vacuum, making the car difficult to drive on the street. Choose a cam that fits your driving needs.

Final Thoughts

Reaching over 400 wheel horsepower with a 5.7 Hemi is not only possible but relatively straightforward with a well-chosen cam, headers, and supporting mods. For those wanting more, forced induction can push the numbers higher while still maintaining daily drivability if built wisely. The key is to plan the entire combination—from cam and induction to fuel and cooling—before turning a wrench. Rely on proven parts from reputable brands and a reputable tuner. With careful execution, your 5.7 Hemi can deliver exhilarating performance that rivals much larger engines.