Is the 5.7 Hemi a 318?

The 5.7 Hemi is not a 318. It is a modern 5.7-liter V8 with a displacement of about 345 cubic inches, while the 318 refers to a much older Mopar small-block engine at 318 cubic inches. They come from different generations and serve different vehicle platforms.

What the numbers mean for Mopar fans

The distinction between the 5.7 Hemi and the 318 goes beyond a few digits. It reflects a shift in design philosophy, technology, and typical vehicle applications that has shaped Mopar’s powertrain lineup for decades.

Here are the core differences that explain why they're not the same engine:

• Displacement: 5.7 Hemi is 5.7 liters (about 345 cubic inches); the 318 is 5.2 liters (318 cubic inches).


• Combustion chamber design: The 5.7 Hemi uses a hemispherical combustion chamber (Hemi) design, while the 318 from the older LA/Wedge family uses a wedge-shaped chamber.


• Technology and systems: The 5.7 Hemi commonly features modern fuel injection, electronic controls, and technologies such as Multi-Displacement System (MDS) and DVVT on many variants; the 318, in its era, relied on older tech and, in earlier versions, carburetion or simpler fuel-injection setups.


• Architecture and era: Both are OHV (pushrod) V8s, but the 5.7 Hemi represents Mopar’s modern Hemi lineage, while the 318 belongs to Mopar’s older LA family of small-block engines.


• Vehicle applications: The 5.7 Hemi is commonly found in contemporary pickups and performance models (e.g., Ram trucks and modern Chargers/ Challengers), whereas the 318 powered a wide range of Mopar cars and trucks during the mid-20th century and beyond in various configurations.

The upshot is straightforward: the 5.7 Hemi is not a 318. The “Hemi” name refers to a hemispherical combustion chamber design, while “318” denotes engine displacement in cubic inches. The two engines belong to different generations with distinct technologies and uses.

Historical context and practical implications

The term Hemi has its roots in the 1950s, when Chrysler popularized hemispherical heads for higher performance. The modern 5.7 Hemi, introduced in the early 2000s, represents a new era of powertrains that pair the traditional pushrod layout with advanced electronics, improved efficiency, and broader model applicability. The 318, by contrast, is a legacy small-block engine that powered countless Mopar models from the 1960s onward and is remembered for its durability and versatility, often in classic restorations or older project cars.

For buyers and enthusiasts, the distinction matters for parts compatibility, maintenance expectations, and performance characteristics. The 5.7 Hemi will require attention to modern fuel systems, electronics, and possible cylinder deactivation features, while the 318 is a veteran engine with a long service history and a different parts ecosystem.

Bottom line

In short, the 5.7 Hemi is not a 318. It is a larger, modern V8 that belongs to Mopar’s current Hemi family, featuring advanced technology and applications in today’s trucks and performance cars. The 318 is an older Mopar small-block engine associated with mid-century designs and a distinct performance profile.

Summary

The 5.7 Hemi and the 318 are two separate Mopar V8s from different eras. The 5.7 Hemi displaces about 345 cubic inches (5.7 L) and showcases modern technologies, while the 318 displaces 318 cubic inches (about 5.2 L) and comes from Mopar’s older LA small-block lineage. Understanding displacement, chamber design, and technology helps explain why these engines are often confused but are not the same engine.

How do I tell if I have a 318 or 360?

You can tell a 318 from a 360 by checking the casting numbers on the driver's side of the block, looking at the front harmonic balancer for balancing marks (grooves/holes on a 360 vs. smooth/holes on a 318), and examining the oil pan's rear sealing face. Another key difference is the left-side engine mount, which is 2 and 7/8 inches for a 318 and 2 and 1/2 inches for a 360, and the alignment of freeze plugs, which are aligned with the main caps on a 360 but not on a 318. 
This video shows how to visually distinguish between a 318 and a 360 engine based on the balancer: 56sYoshimoshiYouTube · Oct 1, 2022
Key identifying features

• Casting numbers: The simplest method is to look for "318" or "360" cast into the side of the engine block, often near the starter or motor mount. 
• Harmonic balancer:
  • 360: Has a large, curved groove or a set of weights on the face for its external balance. 
  • 318: Is internally balanced, so the balancer face will be smooth or have a few small drilled holes, but no large groove. 
• Engine mounts: The left (driver's side) engine mount is physically different between the two. 
  • 318: 2 and 7/8 inches 
  • 360: 2 and 1/2 inches 
• Freeze plugs: Look at the freeze plugs along the side of the block. 
  • 360: The freeze plugs are all aligned with the main bearing caps. 
  • 318: Two of the freeze plugs are not aligned with the main caps. 
• Oil pan: The rear main seal area of the oil pan differs. 
  • 318 and 340: Have a larger rear sealing face. 
  • 360: Has a smaller rear sealing face. 
• Crankshaft main journals:
  • 318: Has 2.50-inch main journals. 
  • 360: Has 2.81-inch main journals. 

You can watch this video to learn about the differences in engine mounts: 1mThe Gas TapYouTube · Nov 14, 2020

Is a 318 a hemi?

The VC and VE Valiants had the 273 V8, but the new VF Valiant in 1969 was fitted with two versions of the "new" Hemi 318 V8. The 318 V8 was only fitted to the 200 series Dodge trucks and up, as I recall, from about 1967 or 1968.

What cars had the 318 engine?

318 V8

• 1983–1989 Chrysler Fifth Avenue.
• 1981–1983 Imperial.
• 1968–1981 Chrysler Valiant.
• 1977–1981 Chrysler LeBaron.
• 1979–1982 Chrysler New Yorker.
• 1981–1983 Imperial.
• 1975–1983 Chrysler Cordoba.
• 1976–1980 Dodge Aspen.

What type of engine is a 5.7 Hemi?

The 5.7 Hemi is a V8 engine from Chrysler, first introduced in 2003. Its name comes from the hemispherical combustion chambers, which allow for greater airflow and power. The engine is known for its durability and is used in various Chrysler, Dodge, Jeep, and Ram vehicles, including the Ram 1500 pickup truck, Dodge Challenger, and Dodge Charger.
 
This video explains the features of the 5.7L Hemi V8 engine: 58sMarspeedYouTube · Feb 14, 2022

• Engine Type: It is a 5.7-liter, 90-degree, pushrod V8 engine. 
• Performance: The Hemi engine is designed for strong acceleration and towing ability. Its output is around 395 horsepower and 410 lb-ft of torque in models like the 2024 Ram 1500. 
• Technology: Modern versions of the engine feature technologies like Variable Valve Timing (VVT) and the Multi-Displacement System (MDS), which can deactivate cylinders to improve fuel efficiency. 
• Application: The 5.7 Hemi is used in a wide range of vehicles, such as the Dodge Durango, Charger, Challenger, Jeep Grand Cherokee, and Ram 1500. 

This video explains the features of the 5.7L Hemi V8 engine: 57sGetty's GarageYouTube · Oct 9, 2023