I've often wondered about this. I have seen K&N oval filters sticking past through the bonnet into the open air so what happens when it
rains? Obviously the filters must get soaked with rainwater so how does that affect the engine?
...... and thinking more about rain, how come when it is raining and we breathe the air, our noses don't get filled up with water? Is it because
out nostrils point down so as we suck air upwards, there is no enough suction to suck in the rain droplets?
I think even it we had our air filters pointing down driving them in to the rain at 60mph at full throttle they would still suck in rain.
quote:
Originally posted by rusty
I think even it we had our air filters pointing down driving them in to the rain at 60mph at full throttle they would still suck in rain.
Have you noticed that your engine is more powerful in cold rather than hot weather... apparently it's to do with the nominal oxygen content at a
given temperature.
Personally I've no idea...
will you be driving a lot in the rain?
quote:
Originally posted by Hellfire
Have you noticed that your engine is more powerful in cold rather than hot weather... apparently it's to do with the nominal oxygen content at a given temperature.
quote:
Originally posted by nick205
will you be driving a lot in the rain?
yes!
rain will get sucked in and there will probably be slightly less power due to more water hence less oxygen. I dont think you would notice though,
especially considering you have less grip in the wet anyway.
isn't water injection used to raise compression ratio's? does rain work in the same way or are the amounts negliable I wonder?!
i thought water jets as used on turbos were used to further cool the charge, to help prevent premeture ignition, hence more boost possible or alternatively more compression.
I can confirn that with the air filter sticking out of the bonnet, and heavy rain..... YOU STILL GET WET!! 
IN the South of France, we hit the most horrendous storm and the car started spluttering - more down to water in the electrics though!
Marcus
The filter will be splash proff, but no more than that. I know since mine sticks up outy of the mini's bonnet and gets soaked. The engine will
start to suck in water. If it's only a little wet, you'll slow down. If it gets really wet, you'll roll to a stop somewhere
inconvienient. If you're really lucky, all the electrics get wet too. 1 guess as to how I know all this.
Funny thing - there is less dust in the air at dusk or during the night also which gives a hike in BHP.....you could really notice it working on the farms at night in the tractor - they'd have a lot more go about them! Oli.
Most petrol engines will develope MORE power in wet conditions, something to do with water moisture increasing compression ratios. Been known in
motorcycling since 1930's to the extent that mist systems supplying water over the carb bell-mouths has been tried.
Not so sure about modern engines with injection and turbos, suspect effect will be less.
Whilst this may be true, a soaked air filter won't let any air through. And what it does will be soo full of water it stops the sparks/flame front from working properly. Or at least it does in my engine.
I suspect that water drawn into the intake gets turned into steam when & if ignition takes place. Steam takes up a lot more room than water, think
it's about 1200 times the volume at atmospheric pressure...
It's the water content in methanol that helps to raise it's knock threshold...
I was reading an old article on Supercharging writen by an Ozzy, Eldred Norman & he recond he had put "A Gallon of water through a three
litre motor in seventy seconds at 5000 rpm without a trace of misfire"... but then I suspect he didn't try it with mixed driving with an
open air filter when it was pissing down...
I supose you could describe your motor as a hybrid...Petrol/Steam.....
Aha, well I happen to have quite a bit of experience on this one! Have a look at my avatar!
The filter on my grasser gets covered not only in water but mud and pretty much everything else too!
No problem at all, water just gets sucked in and vapourised through the engine, you'd need to suck in a huge amount to cause an issue.
Water injection is used in order to quell detonation. It has two properties, firstly it's high latent heat of evaporation cools the inlet charge
and reduces the potential for det. secondly it also has a property which nobody seems to understand whereby even at high charge temps the water
vapour/steam reduces the det risk, seemingly by breaking up the hot gas pockets in the combustion chamber that are the normal starting points for
pre-ignition.
In which case, any idea why mine splutters and stops in the heavy rain? My k&n sits out in the wind straight through the mini's bonnet. Would take a pic, put the head's off at the mo.
Ignition system getting wet ? Usual Mini problem
I had K&N's on a bike years back and that would always start misfiring and eventualy die during a heavy downpour. Eventualy got shot of them and replaced with stock airbox and no more problems. Actualy I lie, I had plenty of other problems with the bike, but cutting out in the wet was no longer one of them...
Ignition sytem's all electronic. Never missed a beat at that end. Would love to fit something standard, but i'm running an ida on a custom manifold. So can't fit/make an air box really as the filter sits entirely outside the car.