worried after driving thru flood water

Strider590

Stoke wrote: »

All this debate because I pointed out that your car can ingest a lot more water through your air intake than you think.

OK, a bit of maths shows that in order to achieve a hydrolock on a 1.5l car with a 10:1 compression ratio at 1000 rpm you would need 150 litres of water a minute, no doubt less would cause damage say 50 but it would need a significant amount of water before hydrolock occurred.

A quick demonstration:

https://www.youtube.com/watch?v=bv4a3k-6Z4w

!!!!!! is that guy doing?

All he's getting out is steam from the water he puts in........ I won't even mention the damage that would do to a catalytic converter.

AdrianC

Stoke wrote: »

OK, a bit of maths shows that in order to achieve a hydrolock on a 1.5l car with a 10:1 compression ratio at 1000 rpm you would need 150 litres of water a minute

Trying to fit 150 litres of water in a minute would certainly cause a problem...

Not least because there ain't even anywhere near that much AIR going in.

Think about it for a moment. On a petrol engine, stochiometry is 14.7:1 air:fuel ratio. That's strictly enforced by the lambda sensor.

So if 150 litres of air were going into the engine per minute at 1,000rpm, then there'd be a tidge over 10 litres of fuel going in, too...

vaio

AdrianC wrote: »

Trying to fit 150 litres of water in a minute would certainly cause a problem...

Not least because there ain't even anywhere near that much AIR going in.

Think about it for a moment. On a petrol engine, stochiometry is 14.7:1 air:fuel ratio. That's strictly enforced by the lambda sensor.

So if 150 litres of air were going into the engine per minute at 1,000rpm, then there'd be a tidge over 10 litres of fuel going in, too...

nice idea but isn't stoichiometric measured at 14.7:1 in terms of mass flow rather than volume?

Joe_Horner

Stoke wrote: »

OK, a bit of maths shows that in order to achieve a hydrolock on a 1.5l car with a 10:1 compression ratio at 1000 rpm you would need 150 litres of water a minute, no doubt less would cause damage say 50 but it would need a significant amount of water before hydrolock occurred.

But you wouldn't need a minute's worth. All you need is one combustion chamber filled. On a 1.5l engine with 10:1 compression, each cylinder is 375cc (assuming a 4 cyl) and the combustion chamber is 37.5cc. So 7 1/2 teaspoons is all it'd take.

In practice you'd need a bit more than that because some would evaporate and it's unlikely to all find it's way into one cylinder during one induction stroke. But half a coke can or so would do it quite happily.

Water injection works because:

(a) it uses FAR less water than that

and

(b) it's injected as a mist, which evaporates before reaching the cylinder (in fact, that's HOW it works - by cooling the chareg as it evaporates)

That is NOT the same as pouring a hundred ml or so of liquid water into the intake!

redux

AdrianC wrote: »

Trying to fit 150 litres of water in a minute would certainly cause a problem...

Not least because there ain't even anywhere near that much AIR going in.

Think about it for a moment. On a petrol engine, stochiometry is 14.7:1 air:fuel ratio. That's strictly enforced by the lambda sensor.

So if 150 litres of air were going into the engine per minute at 1,000rpm, then there'd be a tidge over 10 litres of fuel going in, too...

By mass not volume, as someone already suggested

The volume of air taken into a 1.5 litre engine every minute at 1000 rpm is 750 litres, one fill of 1.5 litres every two revolutions

Richard53

We seem to be going round in circles here. Can we get the terminology right?

Gases and liquids are both fluids.

Gases are compressible, whereas liquids are not (in normal conditions).

"Water" injection is achieved by introducing finely atomised water into the cylinder, not liquid water that you might get sloshed into your air intake. As the atomised water is probably more than 99% air (by volume), it behaves more or less as a gas. The quantity of actual water in the atomised mixture is tiny.

A cylinder ingesting 500cc of air with a few water molecules won't be damaged. A cylinder ingesting 50cc of liquid water almost certainly will.

Nodding_Donkey

I've seen a video on youtube about a guy porting and engine by tipping sandblasting grit into the intake while it was running.

just because something is on youtube doesn't mean it's a good idea

AdrianC

redux wrote: »

By mass not volume, as someone already suggested

True, I'd forgotten that subtle detail...

The volume of air taken into a 1.5 litre engine every minute at 1000 rpm is 750 litres, one fill of 1.5 litres every two revolutions

If it's a diesel, probably.
If it's a petrol, no - unless it's at full throttle.

Stoke

Nodding_Donkey wrote: »

I've seen a video on youtube about a guy porting and engine by tipping sandblasting grit into the intake while it was running.

just because something is on youtube doesn't mean it's a good idea

I agree, but there's no logic to running sand through an intake is there? There has been some logic in the past to water...

redux

AdrianC wrote: »

True, I'd forgotten that subtle detail...



If it's a diesel, probably.
If it's a petrol, no - unless it's at full throttle.

Yes, a throttle valve in a petrol injection system is controlling the flow, but ...

I assumed that if there's a turbocharger it isn't working to add any over pressure at 1000 rpm

I'd be rather surprised if any engine is filling with air at less than atmospheric pressure