OMFG not fluid mechanics, I still have nightmares about that class

 

when i had my evo 8 we had this question. turns out the manufacturer did this right. the bump before the vent causes an increase in air pressure that pulls the air out of the vent. if you remove the vent it causes the air to flow directly back into the engine bay. bad idea... leave the vent louvers alone

 

Well, why dont you give a reason instead of simply stating something as truth? This is the internet, I dont believe it at all everytime someone says they are a professor that teaches blah blah blah because everyone is a professor with a 9 sec car that has a 10" tool on the web. Surely you can appreciate my concern and "learn us something" about your reasoning. No offense or anything. If you give a good reason I'll be sure to use it. I am in an electrical engineering degree program as well so I dont claim to know everything about fluid dynamics either, surely not as much as who you claim to be. Its just that wiki is the easiest source to quote on the web and I am sure there are other principles at play. Bernoulli's is easy for people to understand since its a key principle in how carbs work and in designing intake manifolds. I figured people would relate.

 

Well, leaving aside that the car is well-designed in the first place, and that elements such as the hood (from the Evo) are over-designed, there's just not enough of a flow restriction to make any significant difference to the air flow rate. The flow is a fairly modest flow of air (compared to the vehicle speed) over a reasonably large area. I'm not saying it's impossible that you might see a noticeable improvement in some situation, but I just can't imagine any real situation where it would make any significant difference to the flow coming in via the hood.

In this case, Bernoulli's principle just explains where the pressure driving the flow comes from -- the amount of flow is where the flow restriction comes into the picture, and in an automobile engine there's pretty much a specific airflow for a given power and engine. Opening up the restriction theoretically means more flow for a given pressure, but that's only significant if the restriction is the main limit on the flow (here it isn't), and if the pressure isn't sufficient to drive the desired flow (it almost certainly is sufficient, even with the restrictions in place).

<lecture mode off :->

 

Thanks for taking the time to explain that and not getting pissed. I can buy that for sure.

 

Congratulations for reading the thread title. However, you might want to read my post better. I was using the undertray as an example. Some people thought that by removing the undertray it should provide more airflow to some components and make things cooler, but it doesn't.

 

Congrats for stating the obvious in a redundant manner.

Its common knowledge that removing the under tray is a bad idea. I stated why and yet there are more baseless replies to my argument.

Use that to sweeten your corn flakes.

 

It isn't necessarily a bad idea to remove the undertray, it really depends on the usage of the specific car. There are plenty of people that run without the undertray and have been for a long time.

I tried them again, for the first time, and it still tastes like someone shat in my mouf!

 

I removed mine but hust put them back in due to constant rain, I did notice a drop in temp

 

Thats good to know. What were you using to monitor it and what temps are talking about specifically?

 

Speculation after speculation. Until someone does it and records the data no one can say one way or the other whether or not it will lower the engine bay temp. I see both sides of this. The scientific principle is there to support the lowering of the tempertures, but at the same time you have a lot of engineers paid a lot more than me to design the car to work in a specific way. Only the one way to know for certain.

 

i removed it along time ago from my car. no issues .

 

also if you talking about "restrictor plate" in the evo or the Sti , in that matter any rally breed , you calling that in thewrong name. this is a restrictor or restrictor plate.
Rally cars requered modification on the turbo to run the rally.





so the restrictor plate is something different .

 

Are the air vents on the hood blocked off?!

 

partially. I even took out the hood scoop blocking. Not much there but still.