The Square Four engine was originally designed in 1928 by Edward Turner, the man who later came up with the vertical twin for Triumph. In original form, it started out as a 500cc and was quickly ...

VINTAGE - 1905 - 1944 Due to the rarity of these and other years and models of Ariel, pricing data is still being collected. These are approximate pricing guidelines. Make sure you're protected!

Pioneered by Ariel and used by a few other brands, it was wonderfully balanced and sounded great. How come it's not in use today? Did you know that a square four engine used to be a thing? In fact, ...

The Square Four went through a major revision in 1953, with a new cylinder head and manifolds, prompting a new sub-model designation, Mark II, which ran from 1953 through Ariel’s final year, 1959.