This isn't really an "FAQ"... more of an informational post... since there's really only ONE question:

I just bought a CAI for my car, do I need a Bypass Valve?

No Guarantees
The first thing you should know is that no bypass valve or hydroshield or any other thing you do to your intake will guarantee that you don't ever get water in you engine. These things are just meant to reduce the chances of it happening in certain situations. Common sense can also do quite a bit to reduce those chances if you happen to have some and use it while driving in bad weather.

"It won't happen to me!"
So what are the chances that you'd hydrolock your engine if you didn't have a BPV? Probably slim. But it does happen. Just don't be fooled into thinking the BPV guarantees you won't hydrolock. Its still possible even if you do have one. Its really just another added layer of protection and piece of mind.

Starting off OK
IMO, the tC isn't as bad as some cars may be in allowing water near the filter. Assuming you haven't modified the body panels, the tC's filter is nearly enclosed by the bumper and splash guards. BUT, THIS DOES NOT MEAN THAT THE AREA IS SEALED - just enclosed. So it just helps to prevent splashes from reaching your filter from puddles and such - so if you drive in something deep enough, water WILL get in there.

Big Trouble
By far, the largest concern in possibly hydrolocking your engine would be driving through a VERY deep puddle or a flooded area (under pass? washed out road? flash flood? etc). If you submerge your filter, you're pretty much done for. AEM says their BPV "eliminates the chance of hydrolock should the (...) filter become submerged in water." So what if it's not completely submerged and just part of the filter is? This is where the common sense also comes in that I mentioned. If there is a chance of flooding or it looks like something MIGHT be flooded or you're unsure about a specific "puddle" - DO NOT DRIVE THERE. Find another route or turn around.

So... do you "need" one? Not really. Should you get one if you want to reduce the chances of hydrolock and have some piece of mind? Yes.

Currently the TRD intake comes with a BPV from AEM. And the BPV is available from AEM directly in various sizes for other intakes - though they say it's only for AEM intakes, so some cutting/modifying may be necessary for it to fit a non-AEM system.

Further Reading
tCs do not need a BPV discussion
AEM BPV Info
Injen Hydroshield Info

 

OK guys... without starting some argument if it's really needed or not... what kind of input do you have for this? What should I correct? Where am I wrong?

I just whipped this up, so I'm expecting some more info from you guys. But I still want to keep it SIMPLE!

 

OK... I find it hard to believe that NO ONE has anything to add or correct with this thread... come on people.

 

 

well i think some input from people who have driven through a deep puddle and had an experience where the BPV DID help. i hear a lot of stories of CAI sucking in water and hence the engine is hydro locked. but no one has posted where a BPV has acutally saved them. is there an audible sound that you can tell the BPV has by passed water from your engine?

thanks for the write up btw.

 

i hydrolocked my GSR with a CAI no BPV. i would recommend it on any car with a cai.

 

Ive seen testing on this done a long time ago when aem first released the valve. They did a demo at SEMA where they fully submerged the filter under water and the engine continued running through the BPV. So yes it does work and is not a bad idea to run one at all. I built some splash sheild near my filter to prevent water from even getting to the filter.

 

I don't know if you guys seen this already supposedly its a universal bypass filter that works the same way as AEM. tell me what you guys think. if its garbage, fake, or its good or what....

http://cgi.ebay.com/ebaymotors/2-5-U...spagenameZWDVW

 

this will work. good find. wished it was a 3" dia instead.

after going to OSH to get material for the in-cabin air filter, I just thought of a way to make a bypassvalve for under 3 dollars. once I get around to doing it, i'll post some pictures.

 

sweet indeed, cant wait to see pics... actually they have it from 2.5, 2.75, and 3.0 i believe. just got to look in the sellers store, I'm sure.

 

Go for a short ram if your scared of it, but I had a fender wellCAI with ram air that sat below my front lip on my mustang and I live in the mountains and I never came close to hydro-locking, unless you live somewhere where giant puddles form that would submerge your filter youll be fine without it.

 

<---- yea like Florida....especially the past week.

 

I hydrolocked my first engine back in june at 16000 miles. I was running an Injen with no BPV or shield. The puddle I ended up in was almost up to the doors. I was an idiot for attempting to go through it, and learned my lesson (an $8000 lesson). Thankfully I have awesome insurance.

 

ok so i finally finished my freaking ghetto bypass valve. I used metal screen material because it provides adequate structural support for reconnecting the 2 ends of tubing, while at the same time provide the permeability i needed. I also used foam as the filter medium. here are some pics. there's actually 2 sheets of the screen material. one inside and one outside basically sandwishingthe foam layer. the inner screen layer is heavily taped to the tubing so that it doesn't fall apart if I ever need to change the foam or clean it. and the outer screen material is just to keep the foam in tact. i didn't use hose clamps for the bottom because I ran out of them. remember, this is a very crude setup and i used what I had lying around. the tubing I had was 3" diameter and the gap between the 2 ends is about 2.5 inches. I have tested this, by putting a thin piece of tissue next to it and revving the motor to see if it would get sucked towards it and it doesn't. this is good because I wanted most of the air to come from the main openning which is about 6 inches lower than the ghetto rigged BPV. only when the bottom openning is completely covered up (eg, submerged in water), will the BPV be the less restrictive path for air to be drawn to the motor. I am happy with it. I could have went with the ebay BPV for 20 bucks, but it wouldnt have fit my application because I run an icebox setup as you can see in my integra, it has no room for one. this setup would mostly not work very well if you had a true CAI because a BPV on a true CAI bypasses the main air filter. Mine doesn't.

some of you might say, "if you have an icebox set up, why even put a filter medium since you already have an air filter after it?" it is because the main purpose of the filter medium is not to provide filtration, but to restrict airflow through it when the bottom openning is not restricted. when the bottom openning is submerged in water, etc... then the BPV will become the less restrictive path for air to flow to the motor. (remember that the water needs to travel 6 inches up through a 3" diameter before it even get's to the BPV. this will take a lot energy to do).

here are some pics:

 

for aem bpv...is it better to like use a hacksaw to cut cai or like dremel cut? or do i even need to cut?

 

foe the AEM you dont need to cut just make sure you put it somewhere that wont be under water if the filter is, and in front of your MAF,

 

What size BPV do I need for the Injen?

 

I would like to know this as well.

 

I purchased the ebay special that is listed above. It works really good, and it saved me about 30 bucks compared to the AEM. I have had it for about a year now and no problems yet. But the best BPV money can't buy it's called STAY THE F*CK OUT OF BIG PUDDLES DUMBSH*TS!!!!

 

I installed the AEM bpv on my K&N cold air intake, if anyone does this, make sure you re-use the original coupling and splice into the intake somewhere so the bpv does not flex and break over time like my friends car. Check out the pic!