What fails on an engine running upside down if anything? Oil starvation?

 

oil come on man

 

Actually it depends you wouldn't run into oil starvation at all so long as gravity is reversed. So we need more information? What planet are you running your engine upside down on? That will allow us to better gauge the benefits and risks of such behavior

 

I was thinking of the case where there existed some car an engine mounted upside down, that's all (where the head is on the bottom, and the crankshaft is at the top). I was just wondering if it'd work in theory.

I guess some engines are horizontal, I suppose it would work then, so nevermind?

 

It doesn't matter which way the pistons are going as long as you can get oil where it needs to be. For instance: Mopar's slant six, Porche's flat sixes, and a plethora of radial aircraft engines with pistons upside down and sideways.

The problem with having the head on the bottom is that it would be a real PITA to adjust the valves. A new crankshaft would be a breeze though!

 

BTW if you turned an engine upside down with no mods to the oil system, all the oil would fill the bottom (now the top) of the pistons. If you got it to start and keep running (which is highly unlikely), you would fry all the bearings.

If you try it, let us know the outcome.

 

Oh' boy, a fully aerobatic S.

 

It's only the oiling system that needs to be modified. Engines can run in any orientation. You can no longer have the oil pan in the conventional location and you also have to have a way to retrieve the oil and put it back into the sump.

 

If you're talking about engines in general, not just turning the S2000 engine upside down, then it can work fine. Quite a number of aircraft have in-line engines with the cylinders pointing downward (here and here).

Of course, the lube system has to be specifically designed for this use.

 

Brain, who builds the Ultralites, has a new car with the engine mounted at a 45 degree angle to the right. This lowers the hoodline and shifts the weight slightly towards the passenger side.

Since the oil drains out of the head to the passenger side there is no issue there, all he had to do was basically bend the oil pick up tube to get it to the new low point. He thought he was going to have to make it a dry sump but that wasn't necessary.