worried after driving thru flood water

LandyAndy

pvt wrote: »

That's not pedantic, it's just wrong.

Fluids are compressible, it just requires an enormous amount of pressure to do it. Far far more than a piston and conrod can exert.

A singularity or black hole would do it....

No it doesn't. Air can be compressed by hand using a simple bicycle pump, for example.;)


You wouldn't be confusing fluids with liquids would you?:cool:

Stoke

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

colino

Sometimes people can be stupid all by themselves, others have to post on Youtube to confirm it.

Stoke

colino wrote: »

Sometimes people can be stupid all by themselves, others have to post on Youtube to confirm it.

Maybe so, but he is merely vindicating my point about water injection. WW2 fighter planes used water injection to preserve fuel when flying over sea. It's not just some theory conked up in some kids science book. There are a few, albeit, limited cars over the years that used water injection.

colino

Whoa, your getting your practical applications mixed up there. Putting water through a high idling engine does nothing. Ever tried to get carbon off of a piston crown, valves or combustion chamber? All he is doing is blowing the soot out of the exhaust along with the extra steam he has generated.
Water injection is a genuine performance booster on proper metered applications where a supercharged or turbo charged engine can make both use of the additional water being a coolant to maximise engine performance (engine settings are maxed out and the additional coolant prevents ally pistons melting) and increase the fuel in the chamber as the inducted mix is denser and hence more rich in fuel.

pd52

AdrianC wrote: »

OK, great. So we're in agreement that a 60 limit doesn't imply 60 is always safe and appropriate. Does it imply 50 is always safe and appropriate? 40? 30? No? So why does it say that about 25?

It's quite simple... You drive at a speed from which you can stop in the distance you can see to be clear. The road conditions alone set a safe and appropriate speed. The speed limit merely sets an upper limit for a legal, safe and appropriate speed. No more, no less.

Joe Horner's right when he says that everybody makes mistakes, and that they're not necessarily a bad thing if nobody's hurt, nothing's badly damaged, and - most importantly - you learn from them. Where I disagree with Joe wrt this thread is solely that you don't appear to be learning from it. You appear to be in denial that you were driving too quickly for the conditions. This time, you've been lucky, and your car hasn't been badly damaged. This time.

see post #6 from myself
'it was a narrow country lane, i went around a corner and it goes slightly down hill and i didnt have chance to brake so i think it all went thru the front grilles :eek: it was pretty deep, thought it was going cut out. Hopefully i wont be on here tomorrow talking about a dead Peugeot !

I do need to slow down and pay more attention in future especially with all these floods around '


yet people are still banging on about it even tho i have stated the above days ago before any mention of driving fast etc . I asked for advice on what damage may have been done not for constant belittling of my driving on a one off occasion from the self righteous

AdrianC

pd52 wrote: »

see post #6 from myself

Furry muff - I missed that. My apologies.

However, the line I was questioning regarding 25 being "reasonable" because it was NSL did come from a much later post of yours, #66...

Lum

pd52 wrote: »

yet people are still banging on about it even tho i have stated the above days ago before any mention of driving fast etc . I asked for advice on what damage may have been done not for constant belittling of my driving on a one off occasion from the self righteous

Welcome to the MSE motoring forum. Enjoy your stay.

Retrogamer

Just before Christmas my friend hydrolocked his PD105 engine in his VW Caddy van.

Still starts and "could" drive but it's bent a conrod so sounds rough as a dog if started.

Bit of a pain for him as he just fitted a new DMF, clutch and swapped the gearbox to a 6speed one a few weeks before.

redux

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.

That is an odd deduction.

It doesn't need to be continuous for that long to cause a problem

For a diesel engine that size with a compression ratio of 20, the volume above one piston at top dead centre is 0.01875 litres, about 4 teaspoons as someone said earlier.

If more than that amount is delivered to one cylinder in one cycle the engine cannot compress it.

By the way, on a four stroke engine one cycle consists of two revolutions.