These are LXF models of 4 wide working V4, V6, V8 engines. Assembly uses legal building techniques. The models are built in reallife, and working videos are available.
The original idea was to create a EMD unit for fitting inside locomotives or larger lego vehicles without having to take the full space requirements of the technic V6 engines. E.g. at Model Team scale. The 'pistons' are formed from short 4L axle pieces with a stud on the end. The block assembly is two 1x1 technic bricks with holes. The crank shaft is made from normal technic pieces.
Unfortunately the crank shaft is not ideal, and would benefit from assembly from some custom pieces; but these could be easily reused in other models.