How much is the waste of the power that may be lost in the combination of two engine and where I can find the diagram that shows the relation between rpm and HP in the combined two diesel engine.this two engine combined with a clutch that synchronize two engine for two input in gears and single output.
It's best to connect them at the crank so that they can be timed to fire in a manner that your getting the most amount of power you can. This has been done in applications as small as a .12cc engine all the way up to huge engines that power large ships. The most common place I used to see it is with gas engines for tractor pull. The engines do sync up and will run together when you pair them up thru a clutch
