Nope. The air coming up and out through the vents is air that came in through the radiator and IC. The air entering through the NACA duct goes down across the turbo and out the bottom/back of the engine bay. I've seen no evidence that any "back-swirl" occurs in the engine-bay (i.e., air entering through the NACA duct and exiting through the vents). I've seen the wind-tunnel/smoke-test on this, but can't find the URL for the video any more.

 

I remove mine as of last year, thing to note: engine bay is only slightly dirtier, and during the hot months my engine temp has dropped, so imo worth it to keep the engine slightly cooler

 

Saw another thread on this topic before and someone posted a pic of the FQ400 (X platform) and showed that on that car the vents were entirely removed and open.

I say if the FQ400 comes with them removed and it's making more power (heat) in the same platform without known engine/water problems why not?

I'll be removing mine probably this upcoming weekend.

 

All those vents are for is to keep water out of engine bay. That's it. Some people live in climates that are very rainy. Thank god I live in SoCal. My vents are gone!

 

Way better with out them

 

On what do you base this claim? And, if they are only for blocking water, why are the asymmetrical?

 

^ no one has proof either way. But the reason that they are asymmetrical, I would think, is because there are more sensitive electronics under one side than the other.

 

Here found it. Originally posted on the Mitsu corp website but got removed. The are specifically call hood outlets while the center is the hood inlet. The metal plates serve, supposedly to force more air out the side vents and to block water from sensitive parts of the motor while still allowing some air and heat to escape. If you notice the hood has holes in specific locations to allow water to drain when the hood is down or up since it is hollow. The reason for asymmetrical probably has something to do with heat and water, it's all a trade off for long turn durability vs. cooling.

http://www.mrtperformance.com.au/ima...evo-X-aero.pdf

 

We just hit our first 80+ degree day here so I went out and removed all the vents, including the inlet aluminum heat cover. I left the fiberglass (or whatever it is) cover on to protect the paint on the hood. I know some folks have mentioned the water getting into the intake, but I'm running the stock box so not too worried. If I ever do go with an open element filter, I'll just put the vent cover back on the driver side vent. As far as the air intake scoop that blows air down on the turbo, I'll think it should be good. Fwiw, those little black clips are a pita to get off.

 

Where in that white paper is there anything about water draining? Did you post the correct URL?

 

Exactly! Look at any Evo x that's set up for racing. They don't have the vents still installed. MMCA sells Our cars to people living in all different climates. Some being extremely wet. Only thing you need to be caREFUL WITH IS WASHING THE CAR. Just make sure not to blast a bunch of water through the vents

 

As you can see from that article, It only mentions the vents. Not the restrictor plates inside them

 

There are way too many posts in this thread that are using what is (loosely) called "proof by lack of imagination." It works like this: A. I have a theory about X. B. I can't think of any other explanation for X. C. Therefore, my theory about X must be correct.

Now, you may be correct about the effects and/or the original purpose of the vent-covers. Many members have quite a bit of knowledge and insight. But you need to be careful about asserting that you know what the effects are without data and/or you know why they were put there without something from the designer.

Nothing wrong with speculating, especially if readers learn something about dynamic vs static air pressure, etc. But if you don't have evidence, try to keep your wording consistent with your lack of data. Please.

 

this might be true but as mentioned, no one knows the facts exactly. This is only my opinion but dont you think MMCA would design a vent that worked properly without having to insert a plate into it. Would be more cost effective that way. It seems to be pretty obvious that these are just insurance that your alternator which is on the passenger side and right under the vent that is almost completely blocked is protected. The driver side insert is less restrictive because there is no electrical parts directly underneath. Only my opinion, I dont work for mitsu

 

That was a very slick acknowledgement of what I wrote followed by doing exactly the opposite of what I suggested, but I'll play.

Design? Sure. But what if the best design was asymmetrical? Would Mitsu try to sell another car with an asymmetrical hood? Probably not. They got a lot of grief about the hood on the 2G DSM. Lots of critics ripped it (even if enthusiasts embraced it). I can easily imagine Mitsu worrying about lost sales to funky hood vents and making them symmetrical on the visible side and asymmetrical on the working side.

The other thing that keeps coming up is the issue of rain getting in. Compare the hood vents on Evo Xs to those on previous generations. Yes, it's almost apples to oranges, what with the turbo on the opposite side, but it does make it a tad harder to defend that theory.

But, again, these are all just guesses for now.