The DeSoto Firesweep, particularly the 1958 facelifted 4-door sedan powered by the PowerPack 5.7 V8 engine producing 295 horsepower, represents a pivotal, though ultimately short-lived, moment in the American automotive landscape. Produced from 1957 to 1958, the Firesweep occupied a middle ground within the DeSoto lineup, positioned above the entry-level Fireside but below the more luxurious DeSoto Adventurer. This model year saw significant styling revisions, aiming to modernize the appearance and appeal to a broader customer base. However, despite these efforts, the Firesweep, and the DeSoto brand as a whole, faced increasing competition and ultimately succumbed to market pressures, marking the end of DeSoto production in 1961.
Technical Specifications
| Brand | DeSoto |
| Model | Firesweep |
| Generation | Firesweep I 4-Door Sedan (facelift 1958) |
| Type (Engine) | PowerPack 5.7 V8 (295 Hp) |
| 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 |
| Torque (lb-ft) | 385.01 lb.-ft. @ 2800 rpm |
| Engine displacement | 5735 cm3 |
| Engine displacement (cu. in.) | 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 capacity | 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 |
| Drive wheel | Rear wheel drive |
| Number of gears | 3 |
| Type of gearbox | Manual transmission |
| 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 was the DeSoto PowerPack 5.7 V8 engine. This engine, part of the Chrysler B-series engine family, was a robust and relatively advanced design for its time. It featured a cast iron block and cylinder heads, with a 90-degree V configuration. The 5.7-liter displacement was achieved through a bore of 103.12 mm (4.06 inches) and a stroke of 85.85 mm (3.38 inches). The 10:1 compression ratio, coupled with a four-barrel carburetor, contributed to the engine’s 295 horsepower output at 4600 rpm and 522 Nm (385 lb-ft) of torque at 2800 rpm. The engine utilized an overhead valve (OHV) valvetrain with two valves per cylinder. The standard transmission for this variant was a three-speed manual, although a TorqueFlite automatic transmission was available as an option. The automatic, while offering convenience, did slightly diminish the overall performance potential of the V8.
Driving Characteristics
The 1958 Firesweep with the 5.7 V8 and manual transmission offered a respectable driving experience for the era. While not a sports car, the engine provided ample power for comfortable cruising and confident acceleration. The three-speed manual gearbox allowed for a degree of driver control, but the gear ratios were geared more towards relaxed highway driving than spirited cornering. Compared to the automatic version, the manual offered a more engaging driving experience and slightly improved fuel economy. However, the Firesweep’s substantial weight (approximately 1,770 kg or 3,900 lbs) and relatively soft suspension tuning meant that it wasn’t particularly nimble. The leaf spring rear suspension, while durable, contributed to a somewhat bouncy ride, especially over uneven surfaces.
Equipment & Trim Levels
The 1958 Firesweep came reasonably well-equipped for its price point. Standard features included a spacious interior with comfortable bench seats upholstered in durable cloth or vinyl. The dashboard featured a prominent instrument cluster with gauges for speed, fuel level, coolant temperature, and oil pressure. A basic AM radio was typically included. Optional extras included power steering, power brakes, a continental kit, and upgraded interior trim. The Firesweep’s interior styling was characterized by its mid-century modern aesthetic, with bright trim accents and a focus on passenger comfort. The 4-door sedan body style was the most popular configuration, offering practicality and ease of access for families.
Chassis & Braking
The Firesweep rode on a traditional body-on-frame chassis. The front suspension utilized independent coil springs, providing a more comfortable ride than a solid axle. The rear suspension employed leaf springs, which were robust and capable of handling the car’s weight but offered less sophisticated ride quality. Braking was accomplished via drum brakes on all four wheels, measuring 279 mm in diameter. While adequate for the time, the drum brakes lacked the stopping power and fade resistance of modern disc brakes. Steering was handled by a worm-reduction unit, which provided relatively heavy but precise steering feel.
Market Reception & Comparison
The 1958 Firesweep faced stiff competition from other mid-size American cars, including offerings from Ford, Chevrolet, and Plymouth. Critics generally praised the Firesweep’s stylish design and powerful V8 engine, but also noted its relatively high price and somewhat dated chassis technology. Compared to the more luxurious DeSoto Adventurer, the Firesweep offered a more affordable entry point into the DeSoto brand. However, the Adventurer boasted more powerful engines and a more upscale interior. Fuel economy was typical for the era, averaging around 15-18 miles per gallon. Reliability was generally good, but the carburetor and ignition system required regular maintenance.
Legacy
The 1958 DeSoto Firesweep, while not a commercial success, remains a significant vehicle in American automotive history. It represents a transitional period in automotive design, bridging the gap between the flamboyant styling of the 1950s and the more restrained designs of the 1960s. Today, the Firesweep is a sought-after classic car, particularly among enthusiasts of Mopar vehicles. The PowerPack 5.7 V8 engine is known for its durability and relative ease of maintenance, making it a popular choice for restoration projects. While finding parts can sometimes be challenging, a dedicated community of DeSoto owners and restorers ensures that these classic cars continue to grace the roads for years to come. The 1958 Firesweep serves as a reminder of a bygone era of American automotive optimism and innovation.
