I just bought a new Fujita CAI and im debating whether or not i really need a bypass valve to stop hydro locking. I know fujita does not make one for their CAI intakes, but aem makes one. just wondering if anyone else has this intake and if they have ever had any problem.

BTW its a 99 civic si

 

BUMP. Just installed same intake yesterday and also wondering if I need a bypass valve also 99 si

 

The throttle has to be open a good amount for you to hydrolock the engine. If you don't drive like an idiot in the rain, you should be fine. If you're concerned, get a SRI instead.

I've had my CAI for about five years now, I've driven my car is all sorts of shitty weather, and I've never had an issue.

 

if running a cai i'd rather be safe than sorry and run a bypass

 

The problem with the bypass valve is it kills most of the gains from running a CAI. Air will take the path of least resistance, and you end up changing the effective length of the tube.

 

i love in oregon, one of the more rainy states, at least it seems, i have a cai, and run my car all year round. you have to drive through a good 2-3 feet of water to fully submerge the filter element. i would personally say just skip it, if you're really sketched out get a short ram instead.

 

i don't know how they work in practice, but i imagine the idea would be that the bypass will have more air resistance than the air filter (so that what you're describing doesn't happen), but be able to let air in if the filter becomes soaked/submerged.

 

holy dead thread...

i never through the bypass valve on, and never had an issue. but i can tell you this with as low as my vehicle is, if i went through a semi deep puddle i would hydrolock my motor in a heartbeat. its still not a bad idea to install though.

 

a great idea. i sucked up water in my b16 twice w/ a cold air and got lucky. it didn't lock but if u run cai use it

 

From what I can tell, it's basically like a blow-off valve, except flipped around. When the air filter is submerged, the pressure in the intake tubing drops, and the valve opens. In theory, this shouldn't let air pass through during normal operating conditions. However, the line "Do not mount the bypass valve between the throttle body and pipe because the vehicle performance will suffer" in the installation instructions leads me to believe that some amount of air still gets through when the velocity is high. Honestly, I don't know for sure.

However, even if it seals well under normal conditions, it's still acting as a damper and changing the resonant frequency.