The Ariel Square Four, with its sky-blue body and sky-high speeds, was both a beast and a beauty to behold. Considering its lead designer was none other than Edward Turner, the godfather of high-powered motorcycles, what else could you expect?
At this point in his life, Edward turner was already known for his gifted understand and control of the engineering and design process of twin-cylinder engines; however, when he presented this idea to developers, he was all but laughed out of town.
The original idea for the Ariel Square Four came from an unusual idea to combine multiple pieces from multiple separate engines and Turner’s design for its engine came from those same mismatched engine specifications.
Mismatched or Matched?
The design included two separate parallel-twin engines intricately grafted together around a single crankshaft connected to both engines. This four-cylinder engine was essentially two Frankensteined two-cylinders with alterations made here and there for them to coexist.
The displacement value came out to about 997cc, horsepower came in at 40 at 5,800 revolutions per minute, the weight was a hefty 425 pounds when dry.
Timeline of Versions with Changes
The Ariel Square Four underwent three major changes for a total of four generations.
- Ariel Square Four 4F (1931-1936)
The first model remained unchanged for the first year, but by 1932 Ariel increased the diameter of the cylinder bores to allow for an increased engine displacement of 601cc.
- Ariel Square Four 4G (1936-1949)
To combat the issue of overheating rear cylinder heads, Ariel’s engineers scrapped the engine and started over with a 955cc OHV engine.
- Ariel Square Four Mark I (1949-1953)
Beginning with the Mark I in 1949, the Ariel Square Four experienced a metal substitution. The parts that primarily comprised cast-iron were replaced with stronger and more rust-resistant steel alloys.
- Ariel Square Four Mark II (1953-1959)
The final generation of the Ariel Square Four ended production for the line in 1959. This model sported all newly re-designed cylinder heads and much, much more aluminum.
It is rumored that Ariel considered plans for a Square Four Mark III; however, no such model ever went into production.
The Ariel Square Four in the News
In May of 2019, nearly a dozen classic motorcycles including two Ariel Square Fours and a Moto Guzzi model were discovered stashed away in the barn of a deceased auto-enthusiast and engineer. These models made quite a stir when they went to auction.
Nowadays, everybody from Mila Jovavich to Vince Vaugn ride Triumphs, demonstrating a distinct pattern of success following Edward Turner’s designs. However, not many celebrities openly cruise about on Ariel Square Fours. You can only hope they know what they’re missing!
Unlike a few other older classics, the Ariel Square Four actually has quite a robust social following on social media. In fact, there is one Facebook group with more than 3,000 members.
The Ariel Square Four – A Left-Field Masterpiece
To many developers back in the ‘30s, the master craftsmanship and explosive success experienced by the Ariel Square Four came from out of the blue. There were very few, if any, who actually believed that Edward Turner’s frankensteined design would work.
Fortunately for the world of motorcycles, superbikes, and scooters, Ariel didn’t make that mistake.