| deebee8 | 02-17-2007 01:10 PM |
Flatbottom / Belly Pan
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Didnt really know where to post this, so Here we go.
Anyone know if there is a company that sells a belly pan or flat bottom for the wrx, specifically bugeye.
I know there are company's that sell undertrays for the engine compartment, but im looking to make the entire underside flat.
Im looking specifically for prefabbed stuff, i have already contacted numerous company's in regards to fabricating something, its going to cost a bit more than what i would like to spend.
Help is appreciated!!
Anyone know if there is a company that sells a belly pan or flat bottom for the wrx, specifically bugeye.
I know there are company's that sell undertrays for the engine compartment, but im looking to make the entire underside flat.
Im looking specifically for prefabbed stuff, i have already contacted numerous company's in regards to fabricating something, its going to cost a bit more than what i would like to spend.
Help is appreciated!!
| Uncle Scotty | 02-17-2007 01:17 PM |
...IIRC....somebody did some research some time ago on this regarding the aerodynamic thing and the gist of it was that going all the way back was a waste of time since ya can't seal the underside completely to the road surface with skirts....IIRC....a 1/3 - 1/2 undertray yeilded best results.
| drees | 02-17-2007 03:47 PM |
Even without low skirts, anything you can do to smooth out the underside of the car will reduce drag and decrease lift.
All I've seen is front undertrays that cover up to the front axle line.
Behind that you can get the STi tranny cover from Japan and the STi side underpanel pieces and the STi rear diffuser. Still not flat but better than stock. There's a thread in the Interior forum covering how these bits fit onto a WRX, BIGSKYWRX has fitted them all onto his wagon:
[url]http://forums.nasioc.com/forums/showthread.php?t=814610&highlight=sti+aero[/url]
All I've seen is front undertrays that cover up to the front axle line.
Behind that you can get the STi tranny cover from Japan and the STi side underpanel pieces and the STi rear diffuser. Still not flat but better than stock. There's a thread in the Interior forum covering how these bits fit onto a WRX, BIGSKYWRX has fitted them all onto his wagon:
[url]http://forums.nasioc.com/forums/showthread.php?t=814610&highlight=sti+aero[/url]
| deebee8 | 02-17-2007 04:27 PM |
i saw that thread and it reminded me of the radical, a complete flat bottomed car.
The flat bottom will speed up the air that passes under it and yadayada sucking the car to the road. not here to lecture.
But does anyone know if there is a company that makes such a thing? Or am i going to have to fab one up?
The flat bottom will speed up the air that passes under it and yadayada sucking the car to the road. not here to lecture.
But does anyone know if there is a company that makes such a thing? Or am i going to have to fab one up?
| mav1c | 02-18-2007 12:12 AM |
[QUOTE=deebee8;17088710]i saw that thread and it reminded me of the radical, a complete flat bottomed car.
The flat bottom will speed up the air that passes under it and yadayada sucking the car to the road. not here to lecture.
But does anyone know if there is a company that makes such a thing? Or am i going to have to fab one up?[/QUOTE]
Backwards, I was. :lol:
The flat bottom will speed up the air that passes under it and yadayada sucking the car to the road. not here to lecture.
But does anyone know if there is a company that makes such a thing? Or am i going to have to fab one up?[/QUOTE]
Backwards, I was. :lol:
| PARANOID56 | 02-18-2007 12:33 AM |
nobody that i know of makes what you want. you best bet is to have somebody fab you up one. grab a sheet of thin alu and start cutting :D
Shane
Shane
| DumbUglyDragon | 02-18-2007 12:33 AM |
It works the other way around, air above the car/wing flows faster than the air flowing below it, creating a vacuum above it, thus creating lift. Speeding up the flow beneath the car would thus combat lift.
| drees | 02-18-2007 03:41 AM |
[QUOTE=PARANOID56;17091722]nobody that i know of makes what you want. you best bet is to have somebody fab you up one. grab a sheet of thin alu and start cutting :D[/QUOTE]
Yep! Only slightly difficult trick is to figure out how to attach it to the car. Ideally it'd be fairly easy to replace so you can replace panels if for some reason you hit something and damage one. Probably something like those plastic push pins Subaru uses all over. Be prepared to drill some holes into the under carriage. 1/16" sheet aluminum is easy to work with and light, but fairly flexy so you might need to either reinforce it or be sure it's attached securely in multiple locations.
[QUOTE=DumbUglyDragon;17091727]It works the other way around, air above the car/wing flows faster than the air flowing below it, creating a vacuum above it, thus creating lift. Speeding up the flow beneath the car would thus combat lift.[/QUOTE]
Yep, that is correct. Reduce drag under the car, get air moving faster and you will have less lift.
Yep! Only slightly difficult trick is to figure out how to attach it to the car. Ideally it'd be fairly easy to replace so you can replace panels if for some reason you hit something and damage one. Probably something like those plastic push pins Subaru uses all over. Be prepared to drill some holes into the under carriage. 1/16" sheet aluminum is easy to work with and light, but fairly flexy so you might need to either reinforce it or be sure it's attached securely in multiple locations.
[QUOTE=DumbUglyDragon;17091727]It works the other way around, air above the car/wing flows faster than the air flowing below it, creating a vacuum above it, thus creating lift. Speeding up the flow beneath the car would thus combat lift.[/QUOTE]
Yep, that is correct. Reduce drag under the car, get air moving faster and you will have less lift.
| stormsubaru | 02-18-2007 06:42 AM |
I've seen in racing parts catalogs spring loaded lock pins, there would be some drag from that as they have turn faces, but if it's mounted right the faces could be paralell to the car when tight. I'll look into where i saw those and get back to you (i've seen them on hoods before)
| Howl | 02-18-2007 09:00 AM |
The only car I've noticed with a full belly pan is Ian Crerar's 1977 Porsche 911 rally car.
| Patrick Olsen | 02-18-2007 11:11 AM |
[QUOTE=mav1c;17091581]In theory, if the air going under the car is sped up, it will create more lift, not downforce. Ever see an airplane wing? Same principal. It's the big wings and splitters that create the downforce.[/QUOTE]
:huh: I hope you wrote this when you were buzzed or sleep deprived or something like that, as I wouldn't expect something so incorrect from you, mav1c!
High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.
Pat Olsen
'97 Legacy 2.5GT sedan
:huh: I hope you wrote this when you were buzzed or sleep deprived or something like that, as I wouldn't expect something so incorrect from you, mav1c!
High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.
Pat Olsen
'97 Legacy 2.5GT sedan
| ralliharri | 02-18-2007 11:42 AM |
Ckeck out the rallyshops, they have the big underbody pans for Subarus.
| mav1c | 02-18-2007 11:58 AM |
[QUOTE=Patrick Olsen;17093527]:huh: I hope you wrote this when you were buzzed or sleep deprived or something like that, as I wouldn't expect something so incorrect from you, mav1c!
High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.
Pat Olsen
'97 Legacy 2.5GT sedan[/QUOTE]
OK, I was backwards...I guess. I'll probably get flamed for this question, but an airplane wing is flat on the bottom, and rounded on top, which creates lift, not downforce. Why is that a flat bottom on a car (which ends up being the basically the same shape as a wing) creates downforce, not lift?
[img]http://www.geocities.com/galemcraig/Childmuseum.jpg[/img]
High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.
Pat Olsen
'97 Legacy 2.5GT sedan[/QUOTE]
OK, I was backwards...I guess. I'll probably get flamed for this question, but an airplane wing is flat on the bottom, and rounded on top, which creates lift, not downforce. Why is that a flat bottom on a car (which ends up being the basically the same shape as a wing) creates downforce, not lift?
[img]http://www.geocities.com/galemcraig/Childmuseum.jpg[/img]
| r.o.b | 02-18-2007 12:07 PM |
i see how you are confused but it works a bit different.
The difference is the air under the car has 2 surfaces it touches, your cars underbody and the road. Now if you make the air go faster through this area the pressure is decreased and therefore creates sor of a vaccum effect sucking the car down.
Now if you look at proper spoilers (higher end like f1 etc) they essentially are a airplane wing flipped upside down. They do that because since the wing is only surrounded by air that is the only way to create downforce, unlike how under a car the air is surrounded by 2 surfaces.
hope i explained it fairly straight forward
rob
The difference is the air under the car has 2 surfaces it touches, your cars underbody and the road. Now if you make the air go faster through this area the pressure is decreased and therefore creates sor of a vaccum effect sucking the car down.
Now if you look at proper spoilers (higher end like f1 etc) they essentially are a airplane wing flipped upside down. They do that because since the wing is only surrounded by air that is the only way to create downforce, unlike how under a car the air is surrounded by 2 surfaces.
hope i explained it fairly straight forward
rob
| mav1c | 02-18-2007 12:20 PM |
[QUOTE=r.o.b;17093807]i see how you are confused but it works a bit different.
The difference is the air under the car has 2 surfaces it touches, your cars underbody and the road. Now if you make the air go faster through this area the pressure is decreased and therefore creates sor of a vaccum effect sucking the car down.
Now if you look at proper spoilers (higher end like f1 etc) they essentially are a airplane wing flipped upside down. They do that because since the wing is only surrounded by air that is the only way to create downforce, unlike how under a car the air is surrounded by 2 surfaces.
hope i explained it fairly straight forward
rob[/QUOTE]
Yeah. I figured it had to do with the close proximity to the road. Something I always wondered, just never looked into. :)
The difference is the air under the car has 2 surfaces it touches, your cars underbody and the road. Now if you make the air go faster through this area the pressure is decreased and therefore creates sor of a vaccum effect sucking the car down.
Now if you look at proper spoilers (higher end like f1 etc) they essentially are a airplane wing flipped upside down. They do that because since the wing is only surrounded by air that is the only way to create downforce, unlike how under a car the air is surrounded by 2 surfaces.
hope i explained it fairly straight forward
rob[/QUOTE]
Yeah. I figured it had to do with the close proximity to the road. Something I always wondered, just never looked into. :)
| deebee8 | 02-18-2007 08:54 PM |
Alot of High end cars sport flat bottoms,
Correct me if im wrong but i believe the Enzo sports one ??
i had a piece of sheetmetal laying around, but no lift or proper tools =(.
Correct me if im wrong but i believe the Enzo sports one ??
i had a piece of sheetmetal laying around, but no lift or proper tools =(.
| nitro | 02-18-2007 10:28 PM |
downforce
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What helps the Enzo is the center of the front end has a channel that forces air below which aids in speeding up the air underneath. I like the HKS Kanzi carbon rear diffuser. I would like to find a matching one for the front and the sides.
| afpdl | 02-19-2007 01:00 AM |
[QUOTE=deebee8;17097562]Alot of High end cars sport flat bottoms,
Correct me if im wrong but i believe the Enzo sports one ??
i had a piece of sheetmetal laying around, but no lift or proper tools =(.[/QUOTE]
Almost every Ferrari has a flat bottom. Their swaybars are even housed in an aerodynamic tube to keep them from disrupting the airflow.
Correct me if im wrong but i believe the Enzo sports one ??
i had a piece of sheetmetal laying around, but no lift or proper tools =(.[/QUOTE]
Almost every Ferrari has a flat bottom. Their swaybars are even housed in an aerodynamic tube to keep them from disrupting the airflow.
| drees | 02-19-2007 01:59 AM |
It has nothing to do with "vacuum effect" unless you are inches from the ground or closer. Ignore the ground with our cars, it's not close enough to make that much of a difference.
It has everything to do with the fact that air flowing faster over the top of an object than the bottom will create lift. Smoothing out the bottom will increase speed of the air under the car reducing lift. Some people like to say it increases down force, but in reality it is just reducing lift.
It has everything to do with the fact that air flowing faster over the top of an object than the bottom will create lift. Smoothing out the bottom will increase speed of the air under the car reducing lift. Some people like to say it increases down force, but in reality it is just reducing lift.
| deebee8 | 02-19-2007 02:39 AM |
i am inches from the ground...
but i do appreciate what you are saying, FOR most STREET suby's, a flat bottom would be a stretch as far as a performance enhancement.
but i do appreciate what you are saying, FOR most STREET suby's, a flat bottom would be a stretch as far as a performance enhancement.
| drees | 02-19-2007 02:46 AM |
Is your spoiler and side skirts really less than 3" from the ground?
| Paisan | 02-19-2007 04:00 AM |
A few things...
1) most of the ones you see are ahead of the front axle because you take points or more points in a race class if you bring it back any further than the front axle.
2) I would just pop-rivit it to the underside of the car, that's probably your best bet.
-mike
1) most of the ones you see are ahead of the front axle because you take points or more points in a race class if you bring it back any further than the front axle.
2) I would just pop-rivit it to the underside of the car, that's probably your best bet.
-mike
| maxQ | 02-19-2007 09:23 AM |
[QUOTE=deebee8;17100409]i am inches from the ground...
but i do appreciate what you are saying, FOR most STREET suby's, a flat bottom would be a stretch as far as a performance enhancement.[/QUOTE]
Make sure you take into account the loss in engine cooling due to blocking off flow through the engine bay. In addition, the loss in cooling efficiency causes an increase in engine drag (flow through the radiator slows down because of the higher pressure in the engine bay) so you have to make sure you can decrease lift without an equal increase in drag.
but i do appreciate what you are saying, FOR most STREET suby's, a flat bottom would be a stretch as far as a performance enhancement.[/QUOTE]
Make sure you take into account the loss in engine cooling due to blocking off flow through the engine bay. In addition, the loss in cooling efficiency causes an increase in engine drag (flow through the radiator slows down because of the higher pressure in the engine bay) so you have to make sure you can decrease lift without an equal increase in drag.
| Patrick Olsen | 02-19-2007 06:54 PM |
[QUOTE=drees;17100178]It has nothing to do with "vacuum effect" unless you are inches from the ground or closer. Ignore the ground with our cars, it's not close enough to make that much of a difference.
It has everything to do with the fact that air flowing faster over the top of an object than the bottom will create lift. Smoothing out the bottom will increase speed of the air under the car reducing lift. Some people like to say it increases down force, but in reality it is just reducing lift.[/QUOTE]
That's a good point. I gave mav1c a ":huh:" for his initial reply, but really what I said...
[QUOTE=Patrick Olsen;17093527]High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.[/QUOTE]
... isn't correct, either. As you said, it's not a matter of generating downforce (at least, not on a Subaru), but a matter of generating less lift. A "normal" car has a bottom with quite a bit of protrusions and uneven surfaces to snag air passing under the car, which slows the air down. Giving a smooth underbody means the air slows down less and thus doesn't generate as much lift.
It also (as a side benefit) reduces noise. I'm pretty sure in addition to the top end exotic sports cars having flat bottoms that many luxury cars do, too, to reduce wind noise. I'm pretty sure that's what most (all?) of the Subarus for the past few years have had engine undertray things - to reduce wind noise and improve aero.
Pat
It has everything to do with the fact that air flowing faster over the top of an object than the bottom will create lift. Smoothing out the bottom will increase speed of the air under the car reducing lift. Some people like to say it increases down force, but in reality it is just reducing lift.[/QUOTE]
That's a good point. I gave mav1c a ":huh:" for his initial reply, but really what I said...
[QUOTE=Patrick Olsen;17093527]High velocity = low pressure. Low pressure under large, flat surface on bottom of car = downforce.[/QUOTE]
... isn't correct, either. As you said, it's not a matter of generating downforce (at least, not on a Subaru), but a matter of generating less lift. A "normal" car has a bottom with quite a bit of protrusions and uneven surfaces to snag air passing under the car, which slows the air down. Giving a smooth underbody means the air slows down less and thus doesn't generate as much lift.
It also (as a side benefit) reduces noise. I'm pretty sure in addition to the top end exotic sports cars having flat bottoms that many luxury cars do, too, to reduce wind noise. I'm pretty sure that's what most (all?) of the Subarus for the past few years have had engine undertray things - to reduce wind noise and improve aero.
Pat
| deebee8 | 02-19-2007 07:21 PM |
front air dam is really about 2 inches from the ground, sideskirts are around 4-5?? havent measured, but around there.
i understand that if i add anything to the underside it will add points, Im not concerened on points, i plan to run in ttu.... plan to anyways, funds are getting in the way of the project, isnt that always how it works out?
i understand that if i add anything to the underside it will add points, Im not concerened on points, i plan to run in ttu.... plan to anyways, funds are getting in the way of the project, isnt that always how it works out?
| Paisan | 02-19-2007 07:40 PM |
[QUOTE=deebee8;17108565]front air dam is really about 2 inches from the ground, sideskirts are around 4-5?? havent measured, but around there.
i understand that if i add anything to the underside it will add points, Im not concerened on points, i plan to run in ttu.... plan to anyways, funds are getting in the way of the project, isnt that always how it works out?[/QUOTE]
Yup funds always suck, thats why we are running a 13 year old subaru with 150k miles, and it's still expensive!
-mike
i understand that if i add anything to the underside it will add points, Im not concerened on points, i plan to run in ttu.... plan to anyways, funds are getting in the way of the project, isnt that always how it works out?[/QUOTE]
Yup funds always suck, thats why we are running a 13 year old subaru with 150k miles, and it's still expensive!
-mike
| WickedSTI | 02-19-2007 09:49 PM |
Hot Rod has had a few good reads as of late on aero stuff.I have a 72 Camero that i play with and have been reading the build up on there project F bomb.Here is some good but basic aero info [url]http://www.hotrod.com/techarticles/hdrp_0609_aero_tricks_tips/[/url] There is also info on there recent wind tunnel test on there top speed trials.Not what was ask for i know but this is the best aero real world info i have seen.Brad
| drees | 02-20-2007 01:53 PM |
[QUOTE=deebee8;17108565]front air dam is really about 2 inches from the ground, sideskirts are around 4-5?? havent measured, but around there.[/QUOTE]
Holy crap, that is low! What kind of spoiler/lip are you running and what's your ride height set to?
Holy crap, that is low! What kind of spoiler/lip are you running and what's your ride height set to?
| deebee8 | 02-20-2007 08:34 PM |
i run a home depot front lip!@@ HOORAY!!!.
Essentially its a garden trim piece in the back (For Rigidity Reasons)
And bolted to the front is a 1/8" X 5" Rubber Strip.
Im not rich so i cant but expensive front bumpers and such, i like to fabricate my own things.
When money got thin, i started gutting!!
Essentially its a garden trim piece in the back (For Rigidity Reasons)
And bolted to the front is a 1/8" X 5" Rubber Strip.
Im not rich so i cant but expensive front bumpers and such, i like to fabricate my own things.
When money got thin, i started gutting!!
| Patrick Olsen | 02-20-2007 09:54 PM |
You mentioned your HD air dam in [URL="http://forums.nasioc.com/forums/showthread.php?t=1204638"][U]this thread[/U][/URL], let's see some pics already! I'll probably create something similar when it gets towards track time again in a couple/few months, I want to see what you've done.
Pat
Pat
| deebee8 | 02-20-2007 11:14 PM |
i know im sorry, bad lighting out right now. Well, wait, ill just turn on the garage light!!!
brb with pics
brb with pics
| joshuagore | 02-21-2007 11:48 AM |
[quote=mav1c;17093751]OK, I was backwards...I guess. I'll probably get flamed for this question, but an airplane wing is flat on the bottom, and rounded on top, which creates lift, not downforce. Why is that a flat bottom on a car (which ends up being the basically the same shape as a wing) creates downforce, not lift?
[/quote]
There is no road beneath the wing?
EDIT!!! I was late to the game :)
[/quote]
There is no road beneath the wing?
EDIT!!! I was late to the game :)
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