When I was a kid, I built a plastic model kit of a 1/4 scale “Visible V-8”. What do you know, it’s still available!
(Click image to view on Amazon.com.)
The transparent V-8 engine built by Brian King of Nebraska, U.S., is not only full scale, but is built from the actual moving parts of a General Motors 5.3 litre LS small-block engine. The transparent engine does not, of course, actually burn gasoline: it is powered by an electrical motor to show how the internal parts interact as the engine operates. The following video, in two parts, shows time lapse construction of the transparent engine, from tear-down of the donor engine to completion of the transparent model.
