Why did Ford build two versions of the 351 V8? Which was better, the Cleveland or the Windsor, and why?
Wars have been fought and millions of lives lost over the question of what is better, so I’ll leave that one alone.As for why there are 2 engines with the same displacement, you have to look at the history and what was happening in the late 1960’s. The 351W is a stroked 302, the bore is the same. Produces more torque (which converts to HP because HP is a mathematical calculation based on torque, not a measurement), but stroking a small bore engine comes at a cost, how fast the engine revs. And then there is the stress that increasing the power output of an engine places on the engine itself when the crank is cast, not forged, and the mains are relatively weak.So Ford produced a bigger bore 351C (also available in 400ci) that is heavy duty all around with big heads that can produce a lot of power due to the port size. Coming into 1970, Ford was at a disadvantage in the HP race against Mopar and GM because they have traditionally held on to engine platforms a lot longer than the other companies. The 351C was an answer to the need for more power in production cars, specifically the Mustang, where a bigger block from another engine family wouldn’t work due to space and weight constraints. The 351C is often mischaracterized as a big block when the block casting itself is very similar to the Windsor, the most obvious difference being the timing chain housing is cast into the C block.The 351C is heavier than the W by about 40 lbs. and more expensive to produce, which is probably why Ford didn’t replace the W at the time of introduction. On top of that aspect, you have to keep in mind that Ford produced these engines in giant rust-belt factories that cast and machined all the components in one factory. Changing over a factory to produce new castings and components is really expensive, which is also why Ford didn’t reconfigure the Windsor plant when they introduced the new engine.Then the 1970’s happened and that is probably why, more than any other reason, why the 351C had such a short run in various performance configurations, the M, Q, and R variations. These engines are hard to find because they were only available for 5 years in the desireable configurations. Today, you can buy an entirely aftermarket 351W that is good for 600–700hp for under $20k.