There *is* a lot of fluid available when you fit a scoop under the bumper and drive it through a flood - as lots of Renault owners found out a fw years ago...
Mains water from a hose may have decent pressure behind it but the flow is quite low compared to that.
Indeed. That's why a properly designed cowl induction system fed from the plenum in essentially the same way as the interior vents are fed is my personally preferred arrangement. Works particularly well on LPG when the convertor is referenced from inside the air filter (as should always be the case anyway).
I try not to laugh in the faces of customers who have fitted scoops under the bumper bar. They are of course picking up all the garbage that is floating around near ground level, from sand and smaller sized particles through to animal faeces and plastic bags... :-) As an added bonus, they also get the not-so-cold air from convection carrying the heat up off the nice hot road surface on hot days and water off the road on wet days. :-)
There is a second effect, a big dollop of cold water might do something like warp a hot exhaust valve, even if it isn't enough to hydraulic your engine.
You wouldn't notice that at the time, just find that your engine is down on power over the years.
I'm not saying you are not right, but how would you prove something like that? If you are suggesting that wouldn't notice it at the time but find out your engine is down on power over the years, how are you determining that it was this that caused the effect? There doesn't appear to be a direct cause and effect. It could have been normal wear for all you know.
I would also question the warping of an exhaust valve. I am guessing that the water turns into steam inside the combustion chamber and the valve never 'sees' the water except as steam. How does a valve warp anyway? I've had valves burn, but warp? You would imagine that if a valve warped it wouldn't seat properly and you would notice this immediately as it would lead to a loss of power. Does the valve stem warp? Again, you would think that this would lead to it not seating properly and hence a noticeable drop in power.
I know on the engine that I tried this on, the valves all seemed fine and seemed to be seated properly. I suspect that even if they were coated in water while running, the valves would still have been hotter than they would be on a cold startup.
On the other hand, I can understand that a huge volume of water into an engine would cause a problem. I do think it would be an unusual circumstance though. If it was an old crossflow 6 out of a falcon then the water on the distributor would stop it well before it had the chance of hydraulic damage anyway :)
Dale.
I have no idea. I've haven't encountered it myself, just repeating what might be an urban legend. Doesn't sound too far fetched though.
If you are suggesting that wouldn't notice it at the time
The water could well contact the valve just as it is going in, before the intake valve closes even.
How does a valve warp
Likewise on the engines I've done, which range from an old holden six to a mitsu turbo 16 valve 4. I was pretty careful with the mitsu though.
I suspect that even if they were
It's not the overall temperature, it's the idea of cooling one part of the valve down a lot while the rest is still hot.
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