I suspect the original author’s use of “a built racing engine” was a bad example since there is no factory line for such things as they are too low volume. However, if we loosen the definition of racing engine to include hot rods, then I believe proven factory built designs are highly valued. To give one example:
> The 2JZ-GTE, which sits in the heart of the Supra, is one of the best inline-six out of Japan and easily tunable to 500+ Hp on stock internals.