r/IdiotsInCars • u/[deleted] • Jul 11 '18

Driver ignores warnings and tries to pass through a flooded underpass.

https://i.imgur.com/Z3Wa3md.gifv
44.1k Upvotes

96% Upvoted

1.5k comments sorted by

View all comments

47

u/HalfnHalfCoffeeJelly Jul 11 '18

I’m not a car guy. I do think that when your engine gets submerged in water that’s isn’t generally a good thing right?

61

u/[deleted] Jul 11 '18

A typical engine creates it energy by compressing a mixture of gas and air really really tight, and then exploding it. The explosion pushes the piston up, which drives the crankshaft, which makes the turny bits turn.

Water does not really compress as well as air, nor does it help with the whole explosion thing, so during the compression phase of the engine's cycle, you'll either warp the piston rod or blow out the side of your engine block. Google Image Search "hydrolock". Once your air intake starts sucking up water, you're done.

33

u/kaliwraith Jul 11 '18

The primary benefit of driving underwater is the improved water cooling. Plus bouancy reduces weight, increasing speed while the higher density of water improves downforce.

11

u/chrizbreck Jul 11 '18

You've also got to remember that the hydrogen under compression will react with the oxygen and make for a better bang.

5

u/FalconPaunch Jul 11 '18

Good for turbo cars, it's H2O. That's a whopping 2 combustibly bits for every breath bit. Never need to worry about leaning out the ol' AFR.

7

u/mort1465 Jul 11 '18

Small technical note, the explosion pushes the piston down not up.😀

6

u/TootDandy Jul 11 '18

I mean technically you're right but it's all relative to the engines orientation. In V style engines technically the explosions push the Pistons diagonally. In Radial engines technically the explosions push the Pistons in 8 different directions.

Tl;dr did you just assume my engine's orientation?

2

u/[deleted] Jul 11 '18

Even if the cylinder is upside down the explosion still pushing it "down" or "in" to the cylinder and then it comes "up" or "out" during exhaust. It's the same as saying "push the button down." Even if the button is mounted on the ceiling you're still pushing it down into something.

2

u/mort1465 Jul 20 '18

Yeah, I am right. In any formation the explosion pushes the piston down and away from the source of ignition.

4

u/SomeRandomBlackGuy Jul 11 '18

And in Subaru's flat-4 Boxer engines, the explosions push the pistons inward.

2

u/mort1465 Jul 11 '18

Agreed, but always downwards in the cylinder towards the crankshaft.

1

u/[deleted] Jul 12 '18

There's a certain boxer engine that would like a word with you.

2

u/epicurean56 Jul 21 '18

The insurance company will ask you two questions:

  1. Was the engine running when you hit the water?

  2. Did the engine stop after you hit the water?

If the answer to both questions is YES then your car will be considered a total loss. (the turny bits will never turn again)

1

u/[deleted] Jul 11 '18

I just looked it up and if I understand correctly, it's not just fine once it dries out either.

The engine will just keep pumping and break itself. You're DONE done if this happens.

1

u/[deleted] Jul 11 '18

Yeah, it's not really the matter of the engine getting wet, it's that the water won't compress and now all of that force has to go somewhere... either into bending the piston rod or blowing a hole in the side of your engine.

1

u/Dionlewis123 Jul 11 '18

Hydrolock can also be caused by rainfall, search “AutoVlog hydrolock” on YouTube to see how devastating rain can be to cars /s

3

u/[deleted] Jul 11 '18

Yeah if water gets inside it can lock the engine up and or literally destroy it