Hi guys. I am a Subaru guy (02 WRX) who is possibly moving over to the Evo crowd (03 Evo). It is my belief that the stock intake set-up on the WRX's is great so I kept mine stock (except for a K + N drop-in filter). I was wondering what the general opinion of cold air intakes on the Evos is. From looking at the engine bay the intake set-up is very similar to the WRX intake set-up (except on the opposite side). So if I do get an Evo would it be best to just invest in a K + N drop-in for the stock intake or are you guys getting good results from aftermarket intakes?

P.S. I did a search and didn't really find anything so please don't respond with the usual "Do a search noob" reply.

 

You are going to get mixed results on this and still not get a real answer. Some will argue that once the air goes thru the turbo inlet temp doesn't matter. Others will argue that if inlet temp is cooler it will still be cooler when it leaves the turbo. I hope you find some definate answers because i was wondering this as well.

 

In order to achieve performance benefits, I've read you need some A/F adjustment if you go with an aftermarket intake. So unless you are getting piggyback, AF controller, or ECU flash, I would just stick with a drop-in filter.

 

Turbos don't like long tracts of pre-turbo intake. It tends to create too much vaccuum and can rob horsepower.

 

Just because an intact track is longer doesn't necessarily mean it has more restriction than a shorter one with lots of bends (i.e. stock intake). Ultimately, an intake should be like an intercooler: the least pressure drop, the least turbulent flow, and the coolest charge temperature. Balancing all three is the goal of a good intake. I don't think any aftermarket intake system for the Evo is doing all 3 well right now. They are either good flow and hot air or vica versa.

 

If you were to design a CAI for the Evo, it would probably have a few bends and be too long to be effective.

 

Maybe if you are pulling air from the back of the car

Colder air is ALWAYS better for a turbo motor. It's why we run intercoolers on the car.

As for is the stock air box, I can't answer that.

I know on the VWs they are a horse a peice. Many guys gut the box, and run a cold air line (just a duct) and route air up to the filter. I chose to put the cold air intake on so it's pulling air from in front of the wheel well. I made noticable breathing changes up top. But is one better over another? Dynos say just a few HP.

 

That's not entirely true. I believe APS makes one with 1 large fluid bend that gets cold air from where the intercooler reservoir sits. It's expensive and requires replacing the intercooler with their expensive tank. I am trying to come up with my own idea right now.

 

The biggest problem with a intake for the EVO as well as for the WRX/STI is the MAF not reading like it would with the stock unit. Some intakes make the car go lean and rich compared to the stock. So if you want to run a intake a A/F computer is need to compusate for the diffrent MAF readings.

The stock EVO intake is Fine for the stock turbo. Vishnu make over 400whp on their dyno with the stock box in place (over 500whp on a dyno jet).

If you are considering a EVO the first thing to do is put a nice exhaust and doing a reflash or piggy back on some sort. You will make more power with piggy backs that can adjust timing.

Eric

 

and it felt different from stock instake box. First off, the car itself has a turbo lag. Turbo doesn't kick in till above 3000 RPM. After installing the kit, the turbo spool is earlier. Slightly less than 3000 RPM. But I notice that the torque in the midrange of the car has lessen since I installed the HKS kit. I don't think it's a big torque decrease but the car pulls harder all the way to the redline. There's a trade off. The early spool doesn't elliminate the turbo lag. With the stock air box, you can tell that the RPM doesn't go faster all the way to the redline. I don't feel any decrease and increase in horse power. If there is an increase, there's no way you can feel it.
As far as hot air being suck on the turbo, I don't think it matters. The compressor wheel compresses the air from the air filter and gets routed to the blow off valve to the intercooler pipe. The intercooler pipe has a bigger diameter than the hose that routes air from the blow off valve. More air is coming from the intercooler than the air filter element.
So is it advisable to put it? I say yes because the sound of the blow off valve is worth the audition.

 

I think this is true. Turbo is power in the top end. You want the RPM to be all the way up. If you want power in the low end, use a supercharger.

 

The way I see it, the purpose of a CAI is to get COLD AIR is it not? What the hell kind of air does the stock box get? Look where the intake is! Its INFRONT of the motor. It takes air from the coldest place possible. And it acts like a ram air. I have the K&N drop in filter with a dynoflash to make sure the ecu uses it properly and im loving it. Im not the only one who thinks the stock box with a k&n filter is the best way to go, not to mention cheapest.

The way i see it, an open element filters only advantage is the bov sound is noticable. Other than than, i think they perform worse. I once raced a evo in my evo when he had hks open element filter and jic turboback and i just had nothing at all but a rmr catback. I POUNDED HIM. Im guessing it was the intake he had. Stick with stock and get a k&n drop in if u want performance, get a open element if u want cool sounds.

 

Im also using the stock air box its design is perfect.. And AL recommends it,he can tune AROUND the open element if needed..

Quote from AL DYNOFLASH

"The bushur intake will NOT make any additional power over K & N pannel

Advantages - cleaner looking engine bay - less wieght - better sound

Disdvatnages - stock is better design and more protection for engine - less noise"


Granted alot of people are using open elements,it does make you hear he turbo better,but unless you are using an aftermarket turbo upgrade its not necessary...It becomes a restriction after 400 WHP from what I have heard,granted im not an expert but just my opinion......youll hear alot from this topic

 

You pound on him because you have more mods than him. Not because of the air filter. You have flashed your ECU meaning your tapered PSI is gone. You are pushing 19 psi all the way to the redline. While the guy's turbo pressure was probably around 16 psi when you passed him. It can't be the air filter.

 

I've been modding cars for years and I can honestly say that the EVO 8 has one of the best intake designs by far. If you like throwing away your money go get an aftermarket CAI. My recommendation is to get a K&N drop-in filter and use the intake money to get a ECU reflash.