This practice of pouring water (or other liquid) in the intake manifold is exactly the key to acheive what is called ''liquid lock''.
if the liquid is not vaporized and remains in a liquid form when it reaches the combustion chamber, your have one of the following result:
1) Hole is a piston,
2) bent connecting rod
3) leaking head gasket.
4) bent cylinder head.
These are all big $$$$ to fix.
Don't try this at home.
JackD