07-26-2025, 07:32 PM
The Unlikely Union of Two Icons
Mack Trucks, long known for their rugged in-house engines, occasionally broke tradition by fitting their chassis with Detroit Diesel powerplants—a move that sparked both admiration and controversy. Detroit Diesels, especially the two-stroke 6V92 and 8V71 series, were famed for their high-revving scream and reliability in fleet operations. While Mack purists considered this pairing sacrilegious, others saw it as a practical solution for performance and parts availability.
In the 1970s and 1980s, Roadway Freight and other large carriers ran fleets of R-model Macks powered by Detroits, favoring the engines for their ease of maintenance and fuel economy. The 8V92, for instance, delivered up to 350 horsepower, making it a popular choice for long-haul applications.
Performance and Sound: A Tale of Two Cultures
The contrast between Mack’s signature E9 V8 and Detroit’s two-stroke engines was stark. The E9 was known for its deep, thumping exhaust note, while Detroits emitted a high-pitched whine that earned them nicknames like “Screamin’ Jimmy.” This auditory divide became a cultural marker among drivers—some swore by the visceral growl of a Mack, others preferred the mechanical symphony of a Detroit.
A 1966 Brockway cabover fitted with an 8V71 Detroit was famously pulled from the weeds after 30 years and started under its own power, showcasing the engine’s legendary durability.
Factory Options and Custom Builds
While Mack typically favored its own engines, it did offer Detroit Diesels as factory options in select models. Between 1967 and 1985, Mack produced:
Controversy and Camaraderie
The decision to install Detroits in Macks wasn’t universally loved. One owner joked that putting a Detroit in a Mack was “sick and disturbing,” while others defended the practice as a smart business move. The debate often played out in truck stops and forums, where stories of blown blowers and rebuilt injectors were traded like campfire tales.
Despite the divide, many drivers fondly recall their time behind the wheel of these hybrids. A retired Roadway driver from Winston-Salem remembered the dyno testing and rebuild shop where Detroits were tuned to perfection, and the scrap bins overflowed with worn-out parts—a testament to the engines’ hard use and easy repair.
Legacy and Restoration
Today, Detroit-powered Macks are rare but cherished by collectors. Their unique sound and historical significance make them popular at truck shows and restoration projects. In northern Ontario, a fleet of Superliners with 8V92s served loggers well into the 2000s, with the last unit scrapped only a few years ago.
Meanwhile, enthusiasts continue to hunt for surviving examples, sometimes finding FS models with 6V71s or even 12V71s, tucked away in barns or listed on auction sites. These trucks represent a bygone era when function often trumped brand loyalty, and the open road echoed with the unmistakable wail of a Detroit Diesel.
Conclusion: A Roar That Still Resonates
Detroit Diesel-powered Macks may have been mechanical misfits, but they carved out a niche in trucking history that still resonates today. Whether loved or loathed, their legacy is undeniable—a fusion of engineering philosophies that proved, sometimes, the best solution is the one that simply works.
Mack Trucks, long known for their rugged in-house engines, occasionally broke tradition by fitting their chassis with Detroit Diesel powerplants—a move that sparked both admiration and controversy. Detroit Diesels, especially the two-stroke 6V92 and 8V71 series, were famed for their high-revving scream and reliability in fleet operations. While Mack purists considered this pairing sacrilegious, others saw it as a practical solution for performance and parts availability.
In the 1970s and 1980s, Roadway Freight and other large carriers ran fleets of R-model Macks powered by Detroits, favoring the engines for their ease of maintenance and fuel economy. The 8V92, for instance, delivered up to 350 horsepower, making it a popular choice for long-haul applications.
Performance and Sound: A Tale of Two Cultures
The contrast between Mack’s signature E9 V8 and Detroit’s two-stroke engines was stark. The E9 was known for its deep, thumping exhaust note, while Detroits emitted a high-pitched whine that earned them nicknames like “Screamin’ Jimmy.” This auditory divide became a cultural marker among drivers—some swore by the visceral growl of a Mack, others preferred the mechanical symphony of a Detroit.
A 1966 Brockway cabover fitted with an 8V71 Detroit was famously pulled from the weeds after 30 years and started under its own power, showcasing the engine’s legendary durability.
Factory Options and Custom Builds
While Mack typically favored its own engines, it did offer Detroit Diesels as factory options in select models. Between 1967 and 1985, Mack produced:
- R773 with 8V71: 1,801 units
- R770 with 8V92: 136 units
- R626 with 6V92: 277 units
- RS700 with 12V71: rare but confirmed builds
Controversy and Camaraderie
The decision to install Detroits in Macks wasn’t universally loved. One owner joked that putting a Detroit in a Mack was “sick and disturbing,” while others defended the practice as a smart business move. The debate often played out in truck stops and forums, where stories of blown blowers and rebuilt injectors were traded like campfire tales.
Despite the divide, many drivers fondly recall their time behind the wheel of these hybrids. A retired Roadway driver from Winston-Salem remembered the dyno testing and rebuild shop where Detroits were tuned to perfection, and the scrap bins overflowed with worn-out parts—a testament to the engines’ hard use and easy repair.
Legacy and Restoration
Today, Detroit-powered Macks are rare but cherished by collectors. Their unique sound and historical significance make them popular at truck shows and restoration projects. In northern Ontario, a fleet of Superliners with 8V92s served loggers well into the 2000s, with the last unit scrapped only a few years ago.
Meanwhile, enthusiasts continue to hunt for surviving examples, sometimes finding FS models with 6V71s or even 12V71s, tucked away in barns or listed on auction sites. These trucks represent a bygone era when function often trumped brand loyalty, and the open road echoed with the unmistakable wail of a Detroit Diesel.
Conclusion: A Roar That Still Resonates
Detroit Diesel-powered Macks may have been mechanical misfits, but they carved out a niche in trucking history that still resonates today. Whether loved or loathed, their legacy is undeniable—a fusion of engineering philosophies that proved, sometimes, the best solution is the one that simply works.
