Fender vents - MR2 Owners Club Message Board
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post #1 of 36 (permalink) Old March 7th, 2007, 11:03 Thread Starter
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Fender vents

Looking at this article, not quite sure where the vents where placed.
Anybody tried this, and have a picture?

http://vracing.iwebland.com/vracing/...ontendlift.htm

What about the speed flaps?

http://vracing.iwebland.com/vracing/...speedflaps.htm


Thanks

paul
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post #2 of 36 (permalink) Old March 7th, 2007, 12:09
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The vents are on the front of the inner wheel well plastic. The speed flaps attach to the same part near the bottom.
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post #3 of 36 (permalink) Old March 7th, 2007, 20:06
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you can buy those speed flaps for the bottom of the front arch from toyota. they were standard equipment on the gen 5 mr2 n/a in the uk.

not that exspensive either if i remember correctly, a friend did it for not much more than about $30 your money.
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post #4 of 36 (permalink) Old March 8th, 2007, 22:15 Thread Starter
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Thanks Guys

Will see if I can get some of the OE Toyota ones
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post #5 of 36 (permalink) Old March 9th, 2007, 03:01
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Are you able to tell us the part number?
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post #6 of 36 (permalink) Old March 9th, 2007, 05:13
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I recently refitted my bumper but left the arch liners a bit lose to let air escape like with vents. To my surprise there was quite a difference. I'll be cutting them up soon.

Another place I'm goingto try and vent is in the actual wheel arch behind the wheel (where the side repeaters are on normal cars) as looking at the flow inside the bumper there's a fair potential for venting there.
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post #7 of 36 (permalink) Old March 9th, 2007, 09:20
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Quote:
However, after stiffer springs were installed there was no longer enough downforce being created on the front end to overcome the pressure build up behind the inner fender and within the front bumper. The reason being that the springs were pushing up harder than the air was pushing down.
WTF is this guy talking about??? Not saying his mod doesnt work, but dang, stiffer / lower springs should help (I know they sure did for me).

Not to mention, the springs dont "push up" any harder than the car pushes down on them, AKA, it doesnt matter how stiff they are.
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post #8 of 36 (permalink) Old March 26th, 2007, 14:09
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Keep in mind there is a HUGE difference between downforce and negating lift.
Most "hobbyists, i.e. 90% of the people" think that by adding some sort of aero mod, working or non working, is generatnig downforce.... This is 100% wrong, you are infact lucky if you can get a mod to negate lift.
Case in point is the wheel wells, by "venting them" you help negate lift generated by the highpressure in there at speed. This is not downforce!
Downforce is anything that will make your car "Heavier, than stock" by the pure act of going trough the air.

People should read more, and assume less.

T
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post #9 of 36 (permalink) Old April 16th, 2007, 04:12
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What if I fill my frunk with sandbags? Okay, what if they are aerodynamic sandbags? heh heh
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post #10 of 36 (permalink) Old April 17th, 2007, 15:10
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Quote:
Originally Posted by Tomg
Keep in mind there is a HUGE difference between downforce and negating lift.
Most "hobbyists, i.e. 90% of the people" think that by adding some sort of aero mod, working or non working, is generatnig downforce.... This is 100% wrong, you are infact lucky if you can get a mod to negate lift.
Case in point is the wheel wells, by "venting them" you help negate lift generated by the highpressure in there at speed. This is not downforce!
Downforce is anything that will make your car "Heavier, than stock" by the pure act of going trough the air.

People should read more, and assume less.

T
I am still interested in this though... so don't be so quick to judge. Controlling pressure is just as important as manipulating pressure if you ask me.


Regardless.. I have a swap 3SGTE Celica, I'm interested in more information on these front wheel well vents. I have a feeling it might be a good small step to help the floating feeling the front end gets at higher speeds.

My understanding is that is on the front side of the wheel well? If looking at drivers side front wheel, at the 9 o'clock position of the wheel well? Correct me if I'm wrong. I would think it would be on the rear end of the wheel well, but thats why I'm asking, I am obviously not a scientist lol!
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post #11 of 36 (permalink) Old April 17th, 2007, 15:45
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I am not judging anyone, just setting things straight when facts are clearly perceived incorrectly.

Wrong is wrong regardless of the beholder beliefs.

T
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post #12 of 36 (permalink) Old April 17th, 2007, 16:52
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Quote:
Originally Posted by Tomg
I am not judging anyone, just setting things straight when facts are clearly perceived incorrectly.

Wrong is wrong regardless of the beholder beliefs.

T

I understand..

any help finding information on this though? I am having a hard time finding anything under wheel well vents or vented wheel well, automotive wheel well vents, etc..etc. on the internet search engines.

Anyone?

Thanks
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post #13 of 36 (permalink) Old April 17th, 2007, 18:33
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www.mulsannescorner.com is a great place to start.

Any hole that vents towards the wake of the car works fine. That is why you see many race cars use louvers to make "wakes" by having abrupt angles exposed to the air stream. These generate low pressure pockets directly behind them, and in a way "suck" the air out of the wheel wells. What really happens is that high pressure air migrates to low pressure areas.
Understanding how this works is key, since if you do, you can solve it in a lot of different ways.

T
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post #14 of 36 (permalink) Old April 17th, 2007, 22:02
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Quote:
Originally Posted by Tomg
Understanding how this works is key, since if you do, you can solve it in a lot of different ways.
High to low. Check.

I talked to the owner of a Renault R5 Turbo one time and he pointed out that the vents on the rear fenders (by the taillights) are actually scoops. Air does funny stuff.
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post #15 of 36 (permalink) Old April 18th, 2007, 10:25
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Quote:
Originally Posted by Tomg
www.mulsannescorner.com is a great place to start.

Any hole that vents towards the wake of the car works fine. That is why you see many race cars use louvers to make "wakes" by having abrupt angles exposed to the air stream. These generate low pressure pockets directly behind them, and in a way "suck" the air out of the wheel wells. What really happens is that high pressure air migrates to low pressure areas.
Understanding how this works is key, since if you do, you can solve it in a lot of different ways.

T
Your saying louvers (or cut vents) towards the wake of pressure. I just want to confirm then, that means venting on the wheel well on the front side, not the rear of the wheel well exiting. Correct?
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post #16 of 36 (permalink) Old April 20th, 2007, 01:00
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I am talking about either the top or the rear of the wheel well.
The louvres themselves most often sit on top of the fender with a clear path to the tire.
On others they have a couple of vertical louvres, in the bodywork just behind the wheel well. Some even just cut a section out, and angle the bodywork inwards, to get the air out.

T
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post #17 of 36 (permalink) Old April 20th, 2007, 05:42
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Quote:
Originally Posted by Tomg
I am talking about either the top or the rear of the wheel well.
The louvres themselves most often sit on top of the fender with a clear path to the tire.
On others they have a couple of vertical louvres, in the bodywork just behind the wheel well. Some even just cut a section out, and angle the bodywork inwards, to get the air out.

T
Are you refering to vents like these:


I always wondered what they were for.

I think what Trance is asking, and pretty much what I want to know, is that if you do this mod to the wheel well (plastic piece), you should cut vents in it toward the front bumper of the car. So, if your looking at the drivers side front tire, pretending its a clock, you would want to cut the vents somewhere from 9-10o'clock. Is this correct, or is it towards the rear of the car, more towards 2-3o'clock. Based on what your saying (and the picture of the RX-7) it sounds like these vents should be in the rear, by the door (2-3o'clock).
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post #18 of 36 (permalink) Old April 20th, 2007, 08:22
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Thanks TOM.. I am picturing the LeMan's cars on the site you gave me with the venting on the top of the fender. My original picture in my head though would be venting in the front of the wheel well (9 o'clock) as you spoke about being in the front of the wake. Now we are looking at the vents aft the wheel well, a la the RX7 (2-3 o'clock).

I believe this is a valuable discussion and would like to continue it.

Unfortuntely reaft vents in the body work like the RX7 is not possible for me. It would be more possible to have slit in the top of the wheel well into the engine bay, but then again that just sends the air into the bubble that is the engine bay. The only benefit is that there are louvers on the alltrac hood right above that area, it could work very well for flowing air!

I am very interested in getting the front end of my celica to want to hunker down more than is currently does. A front air dam, new reangled bottom adjustable air foil and a flat bottom piece in the front I believe would help this. Though, I would like to take in as much good information as possible.
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post #19 of 36 (permalink) Old April 20th, 2007, 12:40
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Here is a simplified drawing of how it works.
The red is high pressure, the green is low pressure, so using "wake" slits, or louvres you generate low pressure pockets, the high pressure can migrate too, and hopefully those will be either on top of the car, or the side...under the car is a no no.

Trance4c: you are correct flat pieces, air foil and a air dam would greatly help.
Venting the wheel wells on a regular street car is like putting on a huge GT wing on it...a bit useless.... The things you already have planned should help a lot, maybe a couple of speed flaps too.

T


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post #20 of 36 (permalink) Old April 20th, 2007, 13:06
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Tom.. thanks! That is perfect.

I will look beyond this venting on a street car, I appreciate the perspective.

It will be important though in the future to find out what angle I should put the new bottom air foil on the front bumper.
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