Engine Options for AC Cobra Replicas

Comprehensive overview of small-block, big-block, Ford, Chevrolet, and modern alternatives

The AC Cobra, an automotive legend born in 1962 from the partnership between AC Cars and Carroll Shelby, remains today one of the most widely replicated cars in the world. Its lightweight chassis, timeless silhouette, and raw character have inspired generations of enthusiasts to build their own version—often more reliable, more powerful, or better suited to modern road use.

The choice of engine is the central element of a replica, as it determines not only the available power, but also the balance, road behavior, sound signature, reliability, and overall authenticity of the project.

There are four main families of powerplants: Ford small blocks, Ford big blocks, Chevrolet engines, and modern alternatives (Ford Coyote, Godzilla, custom-built engines, etc.).

Ford Small Blocks: the most common choice for a replica

Ford 289 (4.7 L)

The most iconic engine, as it powered the early “FIA” Cobra 289 models.

• Typical power in replicas: 280 to 350 hp

• Advantages: lightweight, crisp and high-pitched sound, well-balanced handling

• Ideal for: purists, reliability, and spirited road driving

Ford 302 (5.0 L)

The most widespread small block during the 1980s–1990s.

• Power: 260 to 400 hp, depending on build

• Advantages: parts available everywhere, very reasonable cost, strong reliability

• Highly popular in British replicas (DAX, Pilgrim, AK, etc.)

Ford 351 Windsor (5.8 L)

The best power-to-weight compromise.

• Power: 350 to 500+ hp depending on configuration

• Advantages: strong torque, robust architecture, still relatively lightweight

• Excellent for builders wanting a powerful Cobra without going to extremes

Ford Big Blocks: the brutal and mythical solution

This is the iconic configuration of the legendary “427” Cobras, the most famous of all.

Ford FE 427 (7.0 L) — the ultimate Holy Grail

The engine of the original Cobra 427 S/C.

• Power in replicas: 400 to 600 hp, and often much more

• Advantages: ultimate authenticity, massive torque, unmistakable sound

• Drawbacks: very high cost, significant weight, substantial heat output

Other FE engines: 390, 410, 428

Often used in replicas to keep costs under control.

• Typical power: 350 to 450 hp

• Advantages: same FE block as the 427, identical appearance, much lower price

• Perfect for: a faithful big-block Cobra without an excessive budget

Ford 460 / 514 (7.5 to 8.4 L)

Modern big blocks from the 385 series.

• Power: 500 to 700 hp

• Advantages: monstrous output, parts readily available

• Drawbacks: very heavy, high heat generation, require a properly reinforced chassis

Chevrolet engines: a powerful and cost-effective solution

Although Shelby never wanted Chevrolet engines, many replicas use them for their excellent performance-to-price ratio.

Chevrolet 350 Small Block (5.7 L)

The most popular American V8 of all time.

• Power: 250 to 450 hp

• Advantages: extremely reliable, very inexpensive parts, huge range of upgrade options

• Ideal for: tight budgets or reliability-focused builds

Chevrolet 383 Stroker

An evolution of the 350 with increased torque.

• Power: 400–500 hp

• Classic “muscle car” sound, highly appreciated

LS Series (LS1, LS2, LS3, LS7)

GM’s modern and lightweight generation of V8 engines.

• Power: 350 to 650 hp depending on version

• Advantages: reduced weight, modern engine management, reliability, reasonable fuel consumption

• Drawback: less “vintage” in both appearance and sound

Chevrolet Big Block 454 / 502

For a truly monstrous Cobra.

• Power: 450 to 750 hp

• Advantages: titanic torque, imposing visual presence

• Drawbacks: significant front-end weight, requires upgraded brakes and suspension

Ranking of engines for Shelby Cobra replicas

Alternative and modern powerplants

Ford Coyote 5.0 (Gen 1 to Gen 4)

The modern V8 found in Mustangs.

• Power: 420 to 480 hp

• Advantages: very reliable, modern design, DOHC (4 camshafts) — smoother behavior and strong high-rpm performance

• Drawbacks: very wide engine, complex installation in some chassis

Ford Godzilla 7.3 L

Ford’s new V8 with a single camshaft and massive torque.

• Power: 430 to 550+ hp

• Advantages: enormous torque, extremely robust, “old school” look despite its modern design

• Now starting to appear in high-end replicas

Roush Engines (Ford)

Turnkey, factory-built Ford performance engines, very popular.

• 427SR, 427R, 402R…

• Power: 500 to 600 hp

• Advantages: reliability, warranty, outstanding appearance

Custom engines / specialist builders

• Blueprint Engines

• Keith Craft

• Shelby Engines (Las Vegas)

• Danbury Competition Engines

These builders offer custom-built engines, often aimed at high-end Cobra replicas.

How to choose the ideal engine for a Cobra replica?

For absolute authenticity:

• Ford FE 427

• Ford 289
  This is the most historically faithful configuration.

For an excellent performance/reliability balance:

• Ford 351 Windsor

• Chevrolet 383 Stroker

• LS3

For an extreme, no-compromise Cobra:

• Ford 460 / 514

• Chevrolet 502 Big Block

• LS7

For modern / GT-style driving:

• Ford Coyote

• Ford Godzilla