AEM cold air intake with bypass valve

You're talking air bypass valve, AKA blow off valve?

The only "advantage" to adding one is the sound- effect. It will degrade performance. Check Cobb's forum, for Gary Sheehan's (pro Subaru rally driver) comments on atmospheric BOVs.

Stock intake system is considered to be a non- issue up to 300 HP.

Steve

No I'm talking about the bypass valve so water won't be sucked up through the cold air intake. If they offer this why would anyone not get it since it will save your engine?

I run an AEM cold air without a bypass. It does slightly degrade the performance as it is a deviation from the normal dynamic of the pipe. The horsepower loss from the bypass valve is said to be between 2-5, depending on the application and placement of the valve. I'm not that piddly, that's not why I don't use it. My filter terminates about 6-7" off the ground. If I ever have the car in water that deep +4-5" to submerse the filter completely.... well... I just wouldn't drive in water that deep. I don't have a bypass valve because I'm not going to hydrolock the engine. easy as that. If you want peace of mind and can forsee driving through 7-10" of water... by all means get one. 3hp is a small sacrifice when compared with the cost of engine replacement.

Okay, now I'm tracking ya...

...I'd guess the answer would be that people who put those kinda filters on, and people who think about *protecting* the engine, are in two mutually exclusive groups!

Note what that "bypass valve" is doing, when it functions, too...it's letting in totally UNfiltered air.

Neither item makes any sense on a WRX intake, which is pretty well recognized as capable at anything below 300HP...I lost track of what wheels you have.

Steve

Bypass valve is filtered.

It has been proven time and again that 99% of WRX's recieve NO gains whatsoever from a cold air intake, and in fact many people report problems stemming from them. Mainly this is due to improper MAF mount diameter, and the big bend right before it causing turbulence.

A CAI is a VERY poor performance investment on a WRX to begin with, as an up pipe will provide REAL gains in hp and torque, as well as improved spoolup..

Check out these sites,