A few of the limited production engines did have the horsepower, but
they were job-shop-built, wild cam, high compression engines that
needed very high octane fuel and in most cases were not capable of 29"
Hg manifold pressure operation for more than 2 to 10 hours (even if oil
and coolant temps were magically controlled) before extremely loud
noises occurred and smoke, flames and oil went everywhere.

The much storied 426 Hemi ("Race Hemi", "late Hemi", whatever...) was
such an engine. It excelled at NASCAR in its day, thereafter in nitro
burning dragsters with 100% power TBO of something like seven seconds.
But you know why they were never used in marine applications? The
valvetrain was good for a hundred hours, maybe, even at the 350-400 hp
mark, and at 500 hp the lower end had maybe fifteen good hours.
Monteverdi built a sports car called a Hai, with the Hemi, and few were
built-they _could not_ make the Hemi live on the Autobahn for more than
maybe ten thousand miles. Jensen would have nothing whatever to do with
the Hemi.

The "side oiler" Ford 427 is another deal. External oil pipes went out
with the OX-5 and Isadora Duncan era Bugattis-it was a kluge, a patch
to save Ford the trouble of making new patterns and core boxes to do it
right.

There were Americans who "did it right" and who the Europeans learned
from-names like MIller, Goossen, Meyer-Drake, Rentschler, Allison come
to mind-but they had nothing to do with mass production poop out of
Detroit. Let's call a spade a spade here.