The DeSoto Firesweep I 4-Door Sportsman, specifically the 1958 facelift model equipped with the PowerPack 5.7 V8 engine and PowerFlite automatic transmission, represented a significant offering in the American full-size automobile market. Produced for the 1957 and 1958 model years, the Firesweep occupied a middle ground within the DeSoto lineup, positioned above the entry-level Fireside but below the more luxurious Firesweep convertible. This particular configuration aimed to provide a balance of performance, comfort, and style for American families seeking a spacious and powerful sedan.
Technical Specifications
| Brand | DeSoto |
| Model | Firesweep |
| Generation | Firesweep I 4-Door Sportsman (facelift 1958) |
| Type (Engine) | PowerPack 5.7 V8 (295 Hp) PowerFlite |
| Start of production | 1957 |
| End of production | 1958 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 6 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Power | 295 Hp @ 4600 rpm |
| Power per litre | 51.4 Hp/l |
| Torque | 522 Nm @ 2800 rpm / 385.01 lb.-ft. @ 2800 rpm |
| Engine displacement | 5735 cm3 / 349.97 cu. in. |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103.12 mm / 4.06 in. |
| Piston Stroke | 85.85 mm / 3.38 in. |
| Compression ratio | 10:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Carburettor |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV |
| Engine oil capacity | 3.8 l / 4.02 US qt | 3.34 UK qt |
| Coolant | 16.1 l / 17.01 US qt | 14.17 UK qt |
| Fuel tank capacity | 87 l / 22.98 US gal | 19.14 UK gal |
| Length | 5499 mm / 216.5 in. |
| Width | 1989 mm / 78.31 in. |
| Height | 1443 mm / 56.81 in. |
| Wheelbase | 3099 mm / 122.01 in. |
| Front track | 1547 mm / 60.91 in. |
| Rear track | 1516 mm / 59.69 in. |
| Front overhang | 940 mm / 37.01 in. |
| Rear overhang | 1461 mm / 57.52 in. |
| Ride height (ground clearance) | 142 mm / 5.59 in. |
| Minimum turning circle | 14.2 m / 46.59 ft. |
| Approach angle | 16.5° |
| Departure angle | 11.4° |
| Ramp-over angle | 10.5° |
| Drivetrain Architecture | Rear wheel drive. Internal Combustion engine (ICE) |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 2 gears, automatic transmission PowerFlite |
| Front suspension | Independent coil spring |
| Rear suspension | Leaf spring |
| Front brakes | Drum, 279 mm |
| Rear brakes | Drum, 279 mm |
| Steering type | Worm-reduction unit |
Powertrain & Engine Architecture
The heart of the 1958 Firesweep Sportsman was the DeSoto PowerPack 5.7-liter (349.97 cubic inch) V8 engine. This engine, designated with various codes depending on specific calibration, produced 295 horsepower at 4600 rpm and 522 Nm (385 lb-ft) of torque at 2800 rpm. The engine featured a cast iron block and cylinder heads, with a 10:1 compression ratio. It utilized a single Carter carburetor for fuel delivery and an overhead valve (OHV) valvetrain. The PowerFlite automatic transmission, a two-speed unit, was the sole transmission option for this configuration. The PowerFlite, while providing smooth operation, was a relatively simple design compared to some contemporary automatics, prioritizing durability over outright performance.
Driving Characteristics
The combination of the 295 hp V8 and the PowerFlite automatic transmission delivered a driving experience focused on comfortable cruising rather than sporty acceleration. While the engine provided ample torque for everyday driving and passing maneuvers, the two-speed automatic limited the engine’s ability to operate in its optimal power band. Compared to the available manual transmission options in other DeSoto models, the PowerFlite-equipped Firesweep felt less responsive. The gear ratios were geared towards relaxed highway travel, making it a suitable vehicle for long distances. However, it lacked the quick acceleration and engine braking capabilities of a manual transmission.
Equipment & Trim Levels
The Firesweep I 4-Door Sportsman with the PowerPack V8 and PowerFlite transmission was generally well-equipped for its time. Standard features included full wheel covers, a two-tone paint scheme, a spacious interior with cloth and vinyl upholstery, and a heater. Power steering and power brakes were often included, though they could also be ordered as optional extras. The dashboard featured a combination of analog gauges and warning lights, providing essential information to the driver. Optional extras included a radio, air conditioning, and upgraded interior trim packages.
Chassis & Braking
The Firesweep rode on a traditional body-on-frame chassis. Front suspension utilized independent coil springs, providing a relatively comfortable ride. The rear suspension employed leaf springs, a common design for full-size American cars of the era. Braking was accomplished via drum brakes on all four wheels, measuring 279 mm in diameter. While adequate for the vehicle’s weight and intended use, the drum brakes lacked the stopping power and fade resistance of disc brakes, which were becoming increasingly common on more expensive vehicles.
Market Reception & Comparison
The 1958 DeSoto Firesweep, including the 5.7L V8/PowerFlite variant, received mixed reviews. Critics praised the car’s styling and spacious interior, but some found the performance underwhelming compared to competitors like the Ford Fairlane and Chevrolet Bel Air, particularly those equipped with V8 engines and more modern transmissions. The PowerFlite transmission, while smooth, was often criticized for its limited gear selection. Fuel economy, typical for a full-size American car of the late 1950s, was relatively poor. The Firesweep aimed for a balance between luxury and affordability, but it struggled to gain significant market share in a highly competitive segment.
Legacy
The DeSoto Firesweep, and the 1958 model in particular, represents a fleeting moment in American automotive history. DeSoto, as a brand, was discontinued by Chrysler Corporation in 1961 due to declining sales and increasing competition. The PowerPack 5.7 V8 engine, while not particularly innovative, proved to be a durable and reliable powerplant. Today, surviving examples of the 1958 Firesweep are sought after by collectors and enthusiasts, representing a nostalgic reminder of the era of large, stylish American automobiles. The PowerFlite transmission, while simple, is generally considered reliable if properly maintained. However, finding parts for these older vehicles can be challenging, and restoration projects often require significant time and expense.
