To be honest the fall of IQ can be tied to many things including the failure of the family unit and poor parenting.
Look at the children with the best grades and better work ethics often had a solid family unit.
Each generation then is like a Xerox copy and it gets worse with each reproduction in too many cases.
And it has nothing to do with IQ. That child is given the best chances of success for the gifts he/she already has, but no matter how hard they try, may still not possess the necsasarry intelligence to be that heart surgeon or rocket scientist.
No, IQ changes little. A stable enviroment from birth and proper upbringing will give a child no matter his gifts the best chances in life. And there is the rub. Look at how many broken families there are and the chances ruined for so many children because of it. Look at society around you right now. There are to many examples to give you here.
Lycoming = piston-powered engine that a lot of small/not quite as small aircraft use (I seem to recall some use in helicopters as well), they've been used for decades, and are sized from reeeally small to around 400hp eight cylinders (current engines).
...if you were seriously asking.
Current recip aircraft engines are relics from the stone age and are outrageously expensive. The Marvel-Schebler one barrel carburetor on my airplane is very similar to the carburetor that came on the Model-A Ford, costs $2400 new and $1600 rebuilt. (You won't believe how much a new engine costs).
Not entirely certain we should be patting ourselves on the back for that accomplishment, even if in jest. I once received death threats for writing satire stories about Dale Earnhardt Jr...never mind they were actually pro-Junior.