5 Cars That Didn't Use Car Engines: From Helicopters to WWII Torpedo Boats

Automakers have spent more than a century developing engines specifically for cars. But some engineers decided the automotive parts bin wasn't ambitious enough.

Why develop another four-cylinder when you could borrow a flat-six from a helicopter? Why settle for pistons when a turbine could do the job? And if a V12 was powerful enough to propel a WWII torpedo boat, surely it could handle a Bentley.

From experimental gas turbines to enormous aircraft and marine engines, these five cars challenged conventional automotive engineering. Some were serious attempts to reinvent transportation. Others were built because someone had access to an enormous engine and remarkably little interest in moderation.

1

1948 Tucker 48

5.5L Franklin O-335 helicopter flat-six

Preston Tucker's revolutionary sedan was supposed to challenge Detroit's established automakers with advanced safety features, distinctive styling, and unconventional engineering. Its rear-mounted engine was central to that vision, although the powerplant that ultimately reached production wasn't the one Tucker originally intended.

Early development centered on a massive 589-cubic-inch flat-six with hydraulic valve actuation. That engine proved troublesome, prompting Tucker to look outside the automotive industry for a replacement.

The solution came from Air Cooled Motors, the company behind the Franklin O-335 aircraft engine used in helicopters. Tucker adopted a modified version of the 335-cubic-inch (5.5-liter) horizontally opposed six-cylinder, converting it from air cooling to liquid cooling for automotive use.

The resulting engine produced approximately 166 horsepower and 372 lb-ft of torque. Mounted behind the passenger compartment, it drove the rear wheels and helped give the Tucker 48 performance competitive with contemporary American sedans.

The engine was an unusual choice, but not an irrational one. Aircraft-derived powerplants were designed around demanding operating conditions, and the Franklin offered a compact, relatively lightweight alternative to the failed Tucker 589.

Tucker ultimately built just 51 cars, including the prototype, before the company collapsed amid financial and legal difficulties. The Franklin engine, however, remains one of the car's most fascinating engineering decisions.

Engine specifications

Specification	Details
Engine	Modified Franklin O-335
Original application	Aircraft and helicopters
Configuration	Horizontally opposed six-cylinder
Displacement	5.5L / 335 cu in
Output	Approximately 166 hp
Torque	Approximately 372 lb-ft
Cooling	Converted to liquid cooling
Layout	Rear-engine, rear-wheel drive

The Tucker 48 wasn't merely borrowing aircraft technology for publicity. Its helicopter-derived engine became the production car's defining mechanical feature.

2

1963 Chrysler Turbine Car

Chrysler A-831 fourth-generation gas turbine

During the 1950s and 1960s, Chrysler invested heavily in a technology that promised to eliminate many of the limitations of conventional piston engines: the gas turbine. Unlike a piston engine, which generates power through repeated combustion cycles inside cylinders, a gas turbine uses continuous combustion to drive rotating turbine components. The basic principle resembles that of a jet engine, although the Chrysler unit delivered power to the wheels through a transmission rather than producing thrust.

The 1963 Chrysler Turbine Car represented the most ambitious public demonstration of this research.

Its fourth-generation Chrysler A-831 turbine developed approximately 130 horsepower and 425 lb-ft of torque. The power turbine operated at exceptionally high rotational speeds, with a maximum speed around 44,610 rpm.

One of its most unusual features was fuel flexibility. The turbine could operate on a wide range of combustible liquid fuels, including gasoline, diesel, and kerosene. Chrysler famously demonstrated the technology using unconventional fuels, although that didn't mean every possible fuel was practical or recommended.

The car itself was equally distinctive. Designed by Elwood Engel and built with bodies manufactured by Ghia in Italy, it featured copper-colored paint, turbine-inspired styling, and a futuristic interior.

Chrysler produced 55 examples, including five prototypes, and placed 50 cars into a public evaluation program. More than 200 families participated in testing, providing real-world feedback on turbine-powered transportation.

The technology offered smooth operation, relatively few moving parts, and impressive fuel versatility. Unfortunately, high manufacturing costs, fuel consumption, throttle-response characteristics, and emissions challenges made mass production difficult.

Most of the cars were subsequently destroyed, leaving only a small number of survivors.

Engine specifications

Specification	Details
Engine	Chrysler A-831
Original application	Automotive turbine development
Configuration	Regenerative gas turbine
Output	Approximately 130 hp
Torque	Approximately 425 lb-ft
Maximum turbine speed	Approximately 44,610 rpm
Fuel	Multiple liquid fuels
Layout	Front-engine, rear-wheel drive

Chrysler didn't install an aircraft engine in a car. It developed an automotive gas turbine using principles associated with jet propulsion. That distinction makes the project more interesting, not less.

3

1950 Rover JET1

Rover T8 experimental gas turbine

Chrysler wasn't alone in imagining a future without pistons. British manufacturer Rover began investigating gas turbines following its wartime involvement in jet-engine development. Engineers recognized that turbine technology might eventually offer an alternative to the internal-combustion engines powering ordinary automobiles.

The result was the Rover JET1, first demonstrated in 1950 and widely recognized as the first gas-turbine-powered car to run successfully.

The prototype used Rover's experimental T8 gas turbine, mounted behind the passenger compartment. Its initial output was approximately 100 horsepower, and the car featured a relatively conventional-looking open two-seat body.

But its powertrain was anything but conventional.

Instead of reciprocating pistons, the JET1 used a compressor, combustion system, and turbines to generate rotational power. The design demonstrated that a gas turbine could propel a roadgoing vehicle, even if practical challenges remained.

Development continued after the car's introduction. Rover increased its turbine output substantially, eventually reaching roughly 230 horsepower.

In 1952, the JET1 achieved 151.965 mph during testing at Jabbeke in Belgium, establishing a significant benchmark for turbine-powered automobiles.

That performance was impressive for the period, particularly considering that the project was primarily an engineering experiment rather than a production sports car.

However, gas turbines had disadvantages that were difficult to ignore. Fuel consumption, especially at partial load, was a major concern. Heat management, manufacturing costs, and driving characteristics also presented obstacles.

Rover continued exploring turbine technology, including later collaborations and racing applications, but the JET1 never became a production vehicle.

Engine specifications

Specification	Details
Engine	Rover T8
Original application	Experimental automotive turbine
Configuration	Gas turbine
Initial output	Approximately 100 hp
Later output	Approximately 230 hp
Recorded speed	151.965 mph
Record year	1952
Layout	Rear-mounted turbine

The JET1 helped establish that gas turbines could power cars. Making them practical for everyday transportation was another matter entirely.

4

2006 Brutus

46.9L BMW VI aircraft V12

Some automotive projects begin with a design brief. Brutus began with an aircraft engine so enormous that building a car around it seemed like the only reasonable way to put it to use.

Developed at Germany's Technik Museum Sinsheim and presented in 2006, Brutus combines an early American LaFrance fire-engine chassis with a gigantic BMW VI aircraft V12. Its 46.9-liter displacement is roughly eight times that of a modern high-performance V8.

The water-cooled engine produces approximately 550 horsepower at just 1,530 rpm, with a short-duration output quoted as high as 750 horsepower at 1,700 rpm. Those figures are remarkable not only for the power produced, but for how slowly the engine turns compared with modern automotive engines.

The BMW VI was developed for aviation in the 1920s and powered various aircraft, including flying boats. Its master-and-articulating-rod arrangement allowed the enormous V12 to fit into a relatively compact package for its displacement.

Brutus transmits that power through a three-speed gearbox and chain drive to the rear wheels. The underlying chassis dates to approximately 1907, making the vehicle an unusual combination of early motoring technology and later aircraft engineering.

Its braking system is particularly alarming. Brutus has rear brakes only, and the driver sits behind the engine without a conventional firewall. A protective grille offers limited separation from the mechanical components.

The machine has reportedly reached approximately 200 km/h (124 mph) during testing. At that speed, the lack of front brakes becomes considerably more interesting than the horsepower figure.

Engine specifications

Specification	Details
Engine	BMW VI aircraft V12
Original application	Aircraft
Configuration	Water-cooled V12
Displacement	46.9L / 46,930 cc
Continuous output	Approximately 550 hp at 1,530 rpm
Short-duration output	Up to 750 hp at 1,700 rpm
Transmission	Three-speed, rear chain drive
Chassis	Early American LaFrance fire-engine chassis
Recorded performance	Approximately 124 mph

Brutus is less a conventional automobile than a functioning demonstration of what happens when aircraft power meets century-old automotive hardware. The museum's published specifications confirm the enormous engine, chain-drive construction, and distinctly limited braking arrangement.

5

2010 Packard-Bentley “Mavis”

40.8L Packard 4M-2500 marine V12

If Brutus demonstrates what happens when an aircraft engine becomes a car engine, the Packard-Bentley “Mavis” takes the same idea offshore.

Built by British enthusiast Chris Williams, Mavis combines a modified vintage Bentley chassis with an enormous Packard 4M-2500 marine V12. The engine belongs to the family of powerplants used in American military PT boats during World War II.

Its displacement is commonly reported as approximately 42 liters, although descriptions sometimes round the figure differently. That's nearly seven times the displacement of a Bentley Speed Six engine.

The Packard marine V12 is credited with approximately 1,500 horsepower and 2,000 lb-ft of torque in this application, although these are commonly cited figures rather than independently verified dynamometer results for the completed car.

The engine was designed for an entirely different job. In a PT boat, multiple high-output Packard V12s drove propellers to push a relatively lightweight military vessel across the water at high speed.

Installing one in a vintage Bentley chassis required substantial modifications. The resulting machine has an extraordinarily long bonnet, exposed exhaust components, and a single-seat racing layout.

Unlike the Tucker, Chrysler, and Rover, Mavis was never intended to demonstrate a commercially viable automotive powertrain. It belongs to the tradition of aero-engined specials and other extraordinary machines built by enthusiasts who valued mechanical spectacle over practicality.

The car debuted publicly at the Cholmondeley Pageant of Power in 2010, where its enormous engine and dramatic proportions made it difficult to mistake for an ordinary vintage Bentley.

Engine specifications

Specification	Details
Engine	Packard 4M-2500 marine V12
Original application	WWII-era military PT boats
Configuration	Liquid-cooled V12
Displacement	Approximately 42L
Claimed output	Approximately 1,500 hp
Claimed torque	Approximately 2,000 lb-ft
Chassis	Modified vintage Bentley
Builder	Chris Williams
Public debut	2010

Mavis answers a question nobody at Bentley was likely to ask: what if a grand old British racing chassis had to accommodate an American torpedo boat engine? The result is magnificent, thoroughly impractical, and probably best appreciated from a safe distance.

When Automotive Engineering Borrowed From Everything Else

These five vehicles represent three very different approaches to unconventional propulsion.

The Tucker 48 adapted an existing aviation engine to solve a genuine production engineering problem. The Chrysler Turbine Car and Rover JET1 explored whether an entirely different combustion system could replace the piston engine. Brutus and the Packard-Bentley took established aircraft and marine engines and turned them into spectacular one-off machines.

Only the Tucker reached limited customer production with its unconventional engine. The turbine cars demonstrated real engineering potential but couldn't overcome the practical disadvantages of their powertrains. Brutus and Mavis were never intended to be everyday transportation in the first place.

Yet all five reveal something important about automotive history: progress doesn't always come from developing another variation of the same engine. Sometimes it comes from borrowing an idea from aviation, adapting an entirely different propulsion system, or discovering that a boat engine will fit into a car if you're sufficiently determined.

And sometimes the most interesting question isn't whether something should be built, but whether anyone can actually drive it.