CaptainAsia

So I removed the metal sheets that blocks the hood vents (not the scoop) on the front of my hood. My thinking is it would help keep the engine cooler but I haven't noticed any noticeable tempature difference. Anyone done this and noticed any benefits to doing this or am I just letting the elements get under my hood? Thanks!

Iowa999

iTrader: (1)

I'd also be curious to know if opening those vents more ends up being worse, because too much hot air on top of the hood would mean hot air going into the NACA duct meant to cool the turbo. Do you have a temp probe that you can move around under the hood for testing?

CaptainAsia

I haven't done too much testing just intake (AEM, so didn't expect too much), coolant, and engine tempature. All remains pretty much the same. Could the metal covers be there to help guide the air to the back instead of out the top of the hood while moving?

whickedGSR

I believe the metal covers guide the hot air from the rear of the engine out of the engine bay. I will try to locate a link of where i read that information from...

CaptainAsia

Time to put them back in!

momostallion

iTrader: (1)

a diagram of the hood's air channel system would be the best way to know.

either the vents are simple vents that allow engine bay air to escape. (in which case removing the shields would allow a larger area to expel heat).

OR the hood is a designed directional system for cooler air to enter the engine bay through the naca duct and direction of airflow travel and pressure may allow hot air to be channeled out of the vents... in which case the shields may benefit the heat extraction.


personally i would like to remove them because leaves get in the vents but the shields redirect them into the hood channels so now i hear leaves slide around when i open my hood. i have no idea how to remove them.

the negative is removing the shields allows more water to hit my intake heat shield, possibly air filter.

Iowa999

iTrader: (1)

I really doubt that the metal half-covers do any "guiding" of airflow; I really think they only reduce the size of the vents. I say this because the pulling of air through those vents is entirely due to the Bernoulli Effect, which is happening on the top side, not underneath, and the small shift in the center of the vent on the lower side is not going to do very much.

After thinking about this some more, my new guess is that the partial covers are to control the effectiveness of the vents at various speeds. Too large a vent might be ineffective at low speeds, so they are partly covered on production cars. Those that road-race might be better off without the partial covers. Autocrossers and street-drivers might be better off with them.

GsrJake

iTrader: (4)

okay so I thought I was the only one who removed those, IMO those heat shields under the vents do do **** BUT HOLD HEAT IN, have you ever ran your car hard and then touched those things? They're damn hot, it would only make sense that removing them would let more air in, and anyways it looks ugly with those damn things in. I even took off the heat shield under the hood scoop.

CaptainAsia

Any paint damage from the extra heat?

Iowa999

iTrader: (1)

Here's hoping that that was a typo, because these vents let air out, not in. The NACA vent over the turbo lets air in. The vents that (I think that) we've been talking about let air out.

Also, who cares how hot they get. The question is whether removing them makes the engine (and/or the air that the engine is ingesting) hotter or cooler.

momostallion

iTrader: (1)

when i go home i'm going to play with the naca duct and a leaf blower and see what the vent response is like.

if nothing else i will leaf blow the yard.

Iowa999

iTrader: (1)

OK, but please note that you're thread-jacking.

Let's all read the very first sentence of this thread again, OK?

We're (supposed to be) talking about the vents, not the NACA duct.

hackerrei

I would think that the scoop sucks in air on the turbo to help cool it then that air is circled around to the front of the bay and leaves through those vents.
Our it goes on the turbo then through the side panels out the side grills after the wheel arches.
I took out the passanger side plate but left the driver side in because of the air filter and fear of water coming through it when it rain/car wash.

One good side of it is that when you stop or turn off the car it let's a lot of the heat out of the engine bay where if they were blocked off that air would hover at the top of the bay since heat rises.

The only bad thing I can see from removing them is water intake on the filter box or the altanator.

Beside most evo 8-9 guy's remove the big one they have from there hood so it seems like a proven tradition among evo drivers to open the engine bay.

There are alot of up's and downs to every thing.

ZLAYER

Welcome to 2008. I remember this debate from my early days. A lot of people gave opinions. To my knowledge no one every proved anything either way. The argument was that mitsu wouldn't have put them there if the weren't beneficial. Then the rebuttal would be "oh ya how did that work out with the CMC, timing chain (and every other gripe).

Fwiw, I think that they are there to keep out excess water. On a very limited platform, they may have left off the plates for cooling purposes. But in a mass produced product, they are trying to minimize risk of water related gremlins that they'd have to warranty.

Rip them off, I did.

Evolution Z

iTrader: (2)

I removed them as well. I think they are very functional at letting hot air escape. It is clearly evident at a stop light as you look forward, you can see the convection currents (and "see" the hot air rising out, like when you look at a lit bbq grill) of the hot air coming through the vents in the hood