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How much HP does a stock 440 make?

In general, a stock Chrysler 440 V8 produces roughly 350 to 390 horsepower in period-appropriate (gross) ratings, with lower numbers in the later, emissions-focused (net) era. The exact figure depends on year, model, and how the horsepower was rated.

The Chrysler 440 big-block, introduced in the 1960s, powered a range of performance cars from Mopar’s lineup. Horsepower figures varied because factory ratings shifted from SAE gross (used in the late 1960s) to SAE net (adopted in the early 1970s) and because special configurations—such as the Six-Pack—pushed the numbers higher. This article outlines typical stock figures, notable configurations, and how to interpret vintage horsepower data.

Power figures by era and rating method

Below are representative stock configurations and their horsepower, noting that numbers vary by model and whether the engine was rated using SAE gross (typical for the late 1960s) or SAE net (standard from 1971 onward).

1966–1967 440 Magnum (SAE gross): about 375–390 hp; torque roughly 480–500 lb-ft

1968–1969 440 with 4-barrel carburetion (SAE gross): about 350–375 hp; torque about 470–490 lb-ft

1970 440 Magnum (non-Six-Pack 4-barrel): around 370–375 hp (SAE gross); torque near 480 lb-ft

1970 440 Six-Pack (three two-barrel carbs): about 390 hp (SAE gross); torque around 480–490 lb-ft

1971–1974 440 (SAE net ratings): roughly 260–320 hp depending on model, compression, and exhaust/emissions configuration

These ranges reflect the typical factory figures for widely known 440 configurations. Exact numbers can vary by vehicle line (Road Runner, GTX, Barracuda, Challenger, etc.) and by whether the car carried a heavy street trim vs. a dedicated performance option.

Notable 440 configurations and models

Chrysler offered a few standout stock configurations that defined the 440’s performance legacy. The following highlights cover the most influential setups and how they differed in stock form.

440 with 4-barrel carburetor (standard high-performance version): common in GT-class Mopars, typically 350–375 hp gross in the late 1960s

440 Six-Pack (three two-barrel carburetors): the peak performance option for many Mopar models, commonly around 390 hp gross in 1970

440 Magnum variants (late 1960s): configured for higher output, often cited around 375–390 hp gross

1971–1974 440 with net ratings: power dropped into the 260–320 hp range depending on compression and exhaust, reflecting emissions controls and different tuning

For enthusiasts seeking the highest factory output, the Six-Pack 440 from 1970 is frequently cited as the strongest stock 440, while the peak gross figures from the late 1960s reflect the era’s performance culture. The net-era numbers in the early 1970s show the impact of tightening emissions and changes in rating methods.

Understanding ratings: SAE gross vs SAE net

Pre-1971, horsepower was typically published as SAE gross, which measures engine output without accessories and with standard test conditions that favor higher numbers. Starting in the early 1970s, SAE net horsepower became the standard, accounting for compressor losses, belt-driven accessories, exhaust, and cooling systems. This shift explains much of the apparent drop in horsepower from the late 1960s to the early 1970s.

How to verify horsepower for a vintage Mopar today

To determine the exact stock horsepower for a given 440 today, consult primary sources tied to the car’s VIN and build data. Useful references include factory window stickers, original sales brochures, and the build sheet found under the seat or in the glove box. If you’re evaluating a project car, a professional dyno could measure horsepower in a controlled way, but remember that dyno results often reflect modern testing conditions rather than the original factory rating.

Summary: The stock 440’s horsepower varied widely by year, model, and rating method. In the late 1960s, most 440s carried SAE gross ratings in the 375–390 hp range (with Six-Pack variants around 390 hp). In the early 1970s, net ratings typically fell to roughly 260–320 hp due to emissions and testing standards. For precise figures, check the car’s original documentation or consult a Mopar expert who can reference the exact engine code and build sheet.

Was the 440 faster than the 426 Hemi?

The **440 Six-Pack was often faster in stock form, particularly in the quarter mile, but the 426 Hemi had a higher potential for power when modified. Stock 440 Six-Packs generally had better out-of-the-box performance due to how they were tuned and how they hooked up from the line, while the Hemi was a detuned race engine that could be built to produce significantly more power than the 440 with modifications.
You can watch this video to learn about the history and impact of the 426 Hemi: 1mIts Just Cars!YouTube · Jul 31, 2025

Feature	440 Six-Pack	426 Hemi
Stock Performance	Often faster in stock form (e.g., quarter-mile drag racing).	Slower in stock form compared to the 440 Six-Pack.
Power Potential	Lower power potential than the 426 Hemi when both are modified.	Higher power potential when modified, especially with race-spec builds.
Factory Advantage	Lower factory-rated horsepower but with better street-tuned performance.	Higher factory-rated horsepower but often struggled with traction in stock form.
Engine Design	Wedge head engine.	Hemispherical head engine with larger ports and valves.

How much HP does a stock 440i have?

Beautiful 3 L twin scroll turbo inline 6 that makes 320 horsepower. And 332 pound- feet of torque in its base.

How much horsepower can a 440 make?

A 440 engine can make anywhere from 400 to over 800 horsepower, depending on the build. Simple upgrades like a cam, intake, and headers can easily push a basic rebuild from its stock form to 460-500+ hp, while more extensive builds with forced induction (like a supercharger) or high-compression, naturally aspirated setups can achieve 600-800+ hp reliably.
Example horsepower ranges

Basic rebuild: A simple rebuild with aftermarket parts like a camshaft, intake, and headers can get you 460 to over 500 hp.
Streetable builds: With a moderate build, it's possible to make 537 hp with a focus on street-friendly components.
High-performance naturally aspirated: With more advanced combinations and good tuning, you can reach 687 hp or even more.
Forced induction: A supercharger can easily add 500+ hp to the engine, sometimes without needing to modify the engine internals if the boost is kept low.
Extreme builds: Custom, high-end builds that are both well-prepped and balanced have reliably made 700+ hp, with some specific LT1-based 440s reaching 837 hp or more.

How much HP did the 426 Hemi actually make?

The 426 Hemi was officially rated at 425 horsepower, but its actual output was much higher. Dyno tests on stock and near-stock engines show real-world horsepower in the 450 to 500 hp range, and some even exceeded 490 hp. The lower factory rating was likely due to manufacturers under-rating engines for insurance and racing class purposes.

Official vs. actual horsepower

Official rating: 425425425 hp @ 5,0005 comma 0005,000 rpm
Actual output: Dyno tests of stock and rebuilt engines consistently show output between 450450450 and 500500500 hp at higher RPMs. For example, one test found an engine producing 494.4494.4494.4 hp at 5,9505 comma 9505,950 rpm.

Reasons for the discrepancy

Under-rating: Manufacturers sometimes understated engine power to lower insurance premiums or to qualify for certain racing classes.
Detuning: The "street" versions were reportedly detuned from their race-spec counterparts, which could produce even more power.
Modern vs. original: Modern dyno tests may use modern parts and more optimal tuning, which can result in higher numbers than the original engine's rating.

Race-specific versions

Race-specific versions, like those used in NASCAR or factory drag cars, were substantially more powerful, with estimates reaching around 650650650 hp or higher.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.