Hydrolocking a petrol engine
Discussion
Gasses are compressible, liquids are not. Given that both 2- and 4-strole petrol engine cycles involve compression phases of gasses, if the cylinder contains a liquid instead, i.e., the water instead of air has entered the engine through the air intake, the piston can't compress it down, and the engine "hydrolocks", which will happen with any liquid, not just water. It makes no difference that the fuel is ignited by an electrical spark in a petrol engine as opposed to compression in a diesel, since the engine can't complete its operating cycle. Piston simply can't move, which means engine can't operate.
Decky_Q said:
Petrol engines have a larger combustion space but still only millilitres worth.
This, the compression ratio is lower so it would take a little more water to hydrolock a petrol, but doesn't make a huge difference either way if your engine air inlet is submerged.I think it was one or more bent rods that my mum managed in the family Toyota.
QuickQuack said:
Gasses are compressible, liquids are not. Given that both 2- and 4-strole petrol engine cycles involve compression phases of gasses, if the cylinder contains a liquid instead, i.e., the water instead of air has entered the engine through the air intake, the piston can't compress it down, and the engine "hydrolocks", which will happen with any liquid, not just water. It makes no difference that the fuel is ignited by an electrical spark in a petrol engine as opposed to compression in a diesel, since the engine can't complete its operating cycle. Piston simply can't move, which means engine can't operate.
Liquids are compressible, but by a minuscule amount. Their inter-molecular distances are very small, compared to gases, hence their molecular repulsion is far higher resulting in increased pressure. For the situation in question, liquid can be considered in practical terms as incompressible. More here:https://physics.stackexchange.com/questions/394943...
Pica-Pica said:
QuickQuack said:
Gasses are compressible, liquids are not. Given that both 2- and 4-strole petrol engine cycles involve compression phases of gasses, if the cylinder contains a liquid instead, i.e., the water instead of air has entered the engine through the air intake, the piston can't compress it down, and the engine "hydrolocks", which will happen with any liquid, not just water. It makes no difference that the fuel is ignited by an electrical spark in a petrol engine as opposed to compression in a diesel, since the engine can't complete its operating cycle. Piston simply can't move, which means engine can't operate.
Liquids are compressible, but by a minuscule amount. Their inter-molecular distances are very small, compared to gases, hence their molecular repulsion is far higher resulting in increased pressure. For the situation in question, liquid can be considered in practical terms as incompressible. More here:https://physics.stackexchange.com/questions/394943...
Incompressible is all the OP needs to understand the answer to his question without going into the nuances of what little fraction of a percent of the volume of a liquid is made up of compressible intermolecular distances. Even if you're a professor of physics, don't assume that you're the only person here with an equivalent level of scientific knowledge or training. I had a head gasket go on an 800cc Daewoo Matiz. I took the plugs out in the drive and asked a friend to turn the engine over on the starter so I could see if any moisture came out of any of the plug holes.
Anyway he turned the key and a jet of water from the No.1 cylinder went 20ft and hit the back of the garage...
Anyway he turned the key and a jet of water from the No.1 cylinder went 20ft and hit the back of the garage...
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