# Real(not rice) downforce for 4 door B14's



## PatScottAKA99XE (Apr 30, 2002)

hello,

I was wondering how to create downforce/decrease lift, in a 4 door B14. I have questions like - how tall would a rear spoiler have to be to be effective, would venting the top of the hood reduce lift. stuff like that. can any one help


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## Brainstorm (May 7, 2002)

Since our cars are FWD, a wing in the rear won't help you. If you do put a wing (that's meant to create down force) it will hurt your plans to create effective downforce. That's why most FWD cars with big wings are classified as RICE since the wing does nothing for a FWD car other than maybe lifting your front in teh process? I'm not sure what you can do to create downforce in the front (where you really want it.) Short of putting a wing in the front (LOL.. we all know that won't work) and as far as I know there aren't any front facia's built to do create downforce like the F1 racers - well none commercially available anyhow.

I'd like to see if anyone else has any good ideas with respect to creating effective downforce on a FWD car.


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## sethwas (Apr 30, 2002)

Hmm,
Well, the best place (and untapped) is the underbelly of the car. There is where alot of air is rushing in and can be harnessed (venturi effect). Getting this to really work can be tricky since not everyone has a wind tunnel. But basically the first two things you need are front and rear valences that channel the air correctly. Then on the underside you need vents and deflectors that can also channel the air properly. Bolting on a piece of aluminum under the car shouldn't be too hard, and the off-roading boys can hook people up with places that will pound it to the right shape. 
To find a decent shape (as in an educated guess as to what it will look like) copy the design from books that show what effective underbellies look like, and modify the dimensions to fit the Sentras.

Seth


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## morepower2 (Apr 19, 2002)

Brainstorm said:


> *Since our cars are FWD, a wing in the rear won't help you. If you do put a wing (that's meant to create down force) it will hurt your plans to create effective downforce. That's why most FWD cars with big wings are classified as RICE since the wing does nothing for a FWD car other than maybe lifting your front in teh process? I'm not sure what you can do to create downforce in the front (where you really want it.) Short of putting a wing in the front (LOL.. we all know that won't work) and as far as I know there aren't any front facia's built to do create downforce like the F1 racers - well none commercially available anyhow.
> 
> I'd like to see if anyone else has any good ideas with respect to creating effective downforce on a FWD car. *


That is not true at all!

Mike


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## XtremE (Apr 30, 2002)

pat i saw this thing on the tv about spoilers, supposedly the only thing they were invented for was commercials, since there was no more place on the body, a spoiler was added for more ads on a race car
downforce counts if u are in the triple digits....but barely


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## morepower2 (Apr 19, 2002)

XtremE said:


> *
> 
> 
> 
> ...


Spoilers make a huge difference starting from about highways speed.

I don't have the time to argue aero theory on this forum, but on our se-r race car for instance, it is good for about a second a lap on most tracks.

Mike


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## sethwas (Apr 30, 2002)

Well,
To comment on the above 3 threads:
First a disclaimer: these are short anwers. Don't expect too much.

FWD, RWD, 4WD, it doesn't matter. The shape of the car dictates aerodynamics, not the drivetrain. In drag racing where a load is produced on one end of the body, where the power goes makes a difference, but that is more of a suspension issue than aero. Aero comes in farther down the 1320.

Small lip spoilers on cars do nothing since they are not in the air path coming over the roof and hence do more swirling the air behind the car creating drag. In some correctly placed lip spoilers this swirling air helps diffuse the rear end lift and even smooths out the air sometimes coming off the roof maiking the car more efficent. It all depends.

Big wings. These need to be tall enough to hit the oncoming air from over the roof of the car. Depending on the shape of the car and the amount of lift generated, the spoiler would have to be so high and at such an angle to counteract this lift without creating too much drag. It isn't effective at slow speeds (below highway) since the sheer weight of the car and the design do not permit airflow problems to be created and therefore amended. 

The main notion of aerodynamic enhancement is only viable at high speed where stability gets sketchy. You have to know where the air is going at these speeds, and be able to move it accordingly.

No one knows how to perfectly do this since much of fluid dynamics is still theory. Computers, even nowadays, can barely hack out the functions to properly map airflow. However the science is moving along and is fairly sophisticated right now. Still, unless you race, or speed alot, cooling is the only real airflow problems you should worry about.

Seth


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## James (Apr 29, 2002)

forget all that mumbo jumbo. a spoiler is designed like an upside down airplane wing. instead of creating lift up it pushes you down. you need to be a pretty fast speed to get a significant amount of force (airplanes don't take off at 35 mph do they?)... they work alright, everything said in the above posts are correct.

venting the top of the hood? no, i don't think it will reduce lift as much as it will increase wind resistance.


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## barnoun (May 7, 2002)

If you want to decrease lift in the front, make a front splitter, like this one.


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## Sentrixx (Apr 30, 2002)

Brainstorm said:


> *Since our cars are FWD, a wing in the rear won't help you. If you do put a wing (that's meant to create down force) it will hurt your plans to create effective downforce. That's why most FWD cars with big wings are classified as RICE since the wing does nothing for a FWD car other than maybe lifting your front in teh process? I'm not sure what you can do to create downforce in the front (where you really want it.) Short of putting a wing in the front (LOL.. we all know that won't work) and as far as I know there aren't any front facia's built to do create downforce like the F1 racers - well none commercially available anyhow.
> 
> I'd like to see if anyone else has any good ideas with respect to creating effective downforce on a FWD car. *



Well I have a good idea that might be pretty affective BUT, I don't have the money for a mold.


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## sethwas (Apr 30, 2002)

> (airplanes don't take off at 35 mph do they?)...


...ummm...actually, they do. 2 seater Cessnas take off at 55, and ultralights can take off at a jogging pace. However you're thinking of a 747 which weighs 200,000 pounds, or 80 SUVs. There, takeoff is around 160mph or so.
"rotate"

Seth


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## James (Apr 29, 2002)

sethwas said:


> *
> ...ummm...actually, they do. 2 seater Cessnas take off at 55, and ultralights can take off at a jogging pace. However you're thinking of a 747 which weighs 200,000 pounds, or 80 SUVs. There, takeoff is around 160mph or so.
> "rotate"
> 
> Seth *


what's your point?


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## Brainstorm (May 7, 2002)

Found an interesting bits of info on aerodynamics and the role of spoilers and body kits...

here


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## PatScottAKA99XE (Apr 30, 2002)

Whoa!!... Here are my replies to each one of you.

Brainstorm, 
Read Mike's second post in this thread...Nuff said.

setwas,
I think we are on the same wave-length(under-body stuff).

morepower2,
We ARE on the same wave, thank you.

XtremE,
Just for adds? I dont think the worlds best/fastest race cars would sacrifice the weight and areo drag of a wing to get more adds. D-force counts in triple digits..Thats where I am going.

James, 
Venting the hood wont help you say, you know those big openings for air in the front of cars..to let air hit the radiator??? what do you think that air does after that..disappear? No it creates a high pressure bubble under the front of your car effectively lifting the front end(making a understeer prone FWD even worse). Tottaly tape off the front of your car(leave a small opening for cooling air) and go for a high speed run, you will know what I am talking about.

Here are some of my other thoughts on car aero.

Lips/splitters: Put low enough they help divert air, stopping some from going under the car and becoming hella turbulent. Creating some "weird happenings" and lift down there at high speeds. This is where under-trays and diffusers come into play.

Under-body stuff ie. trays and diffusers: designed properly will smooth out that "dirty" air, and possibly create "suction". Do you think an F1 car gets enough down force to squash hella stiff springs and theoreticly run upside-down, from its front and rear wings? I don't. Wings that good would create hella drag.

Rear spoilers: depending on the tilt of the rear window(20deg I think) air will not "stick" to it and flow down to a oem(read useless) spoiler, and if it does the air will be so "dirty(read tubulent) the spoiler doesnt do a hell of a lot. Think of this.. cars with a rear window less than 20deg, that have a wing and a rear wiper dont utilize the wing because the wiper "dirtys" the air. For a sedan like say a B14 you need a wing that will peak up into the "clean" air over the roof of the car. I may look "rice", but its less rice than riding around on Sportlines with stock length struts(I'm guilty on that one).

Did I forget anything???
For those that think I am "ricing" or not going to acomplish anything with my aero ideas, remember this when a Charcoal Mist 99 Sentra XE blows by you on a corner because its sticking and your sliding.

"We mock what we dont understand"

P.S. Every "real" racing B14 I have ever seen has a wing.


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## PatScottAKA99XE (Apr 30, 2002)

morepower2,

Got any pics/specs on that spoiler? Id like to see.


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## James (Apr 29, 2002)

ok let me digress...

you're right, it does create the high pressure you are talking about. I said "i think", i'm not an expert on aerodynamics i just know the theory.

well here's a question for you then, do you think a car driven on the road daily will suffer more (whether that be from power, cd, or gas mileage, blah blah blah) from the high pressure under the front of the car or from the increase in drag in cutting holes in your hood?


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## PatScottAKA99XE (Apr 30, 2002)

James,

Not every day is a road day.

Drag from hole/vents in hood. Expain as I am not aware of that, If there is I would imagine that it is slight and the benifts could out-weigh the costs


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## James (Apr 29, 2002)

well i have no proof and no evidence. this is something that can only be known if we could test it and i don't have the equipment here. i'm only going by the logic that it's like opening your window, it creates enough disruption in the flow of air that it can affect your car...


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## PatScottAKA99XE (Apr 30, 2002)

James,
I see your point, but in that case the air is going in to the car, in mine its comming out. I agree that it would have to be tested.


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## Guest (May 26, 2002)

What does your car run where you would need the downforce especially in a sentra....


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## PatScottAKA99XE (Apr 30, 2002)

QuikBlackSentra,

In a desert out west, where a secret military base is thought to be. Its not really a military base, thats just "dis-information". Its really a secret Nismo test facility. All of those "UFO's" are really low flying Nissans. Now I am going to have to kill every one who reads this thread....lol

Seriously, I am interested in all forms of car perfomance. I just want to build stuff and try it out. My real high-speed test spot is a long stretch of Vermonts finest Intersate. Stock Sentra on the limiter=Scary, My lowered and stiffend up Sentra=a lot better.


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## Teknokid (Jun 1, 2002)

Okay so im pretty much confused. Could you just answer whether or not rear wings create downforce or not? I understand if they are above the top of the car they would. What about solar wings? They kind of extend the roof of the car. I seen an *cough*accord*cough* wagon with a small wing on the roof, would this help in anyway?


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## Teknokid (Jun 1, 2002)

Okay so im pretty much confused. Could you just answer whether or not rear wings create downforce or not? I understand if they are above the top of the car they would. What about solar wings? They kind of extend the roof of the car. I seen an *cough*accord*cough* wagon with a small wing on the roof, would this help in anyway?


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## PatScottAKA99XE (Apr 30, 2002)

Chris,
Yes theye create D-force, but only if properly designed.
The lil roof ones are for hatch backs and wagons, cuz thats all that will fit. I was once told that they do work. BTW on a car like ours, they do not have to be above the roof line, just high enough to catch clean air off of the roof of the car. Thats one of the questions no one has answered for me yet...How tall does it have to be???


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## SXSENIS (Jun 9, 2002)

the oem wing on some sentras and se-r's actually provide down force at 45 mph..stillens type 2 wing provides a bit more...though tall wing wont be good til about 120+mph...the front doesnt need down force because all the weight is up there..its nice to have some on the rear because if you have ever driven hard enough to get the back end swurly it'll make your heart drop!!!!..if you want more tracktion[?] up front go with wider tires...


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## Crono1321 (Jun 8, 2002)

The purpose of downforce via spoiler is to add the extra pressure on the wheels to make them spin harder. This is why a FWD car DOES NOT need a huge spoiler. The first person to reply to this had the right answer. A 240sx has use for this, as well as a booming stereo in the trunk because all this extra weight goes on the back wheels. In a FWD car it justs slows it down. And if you are thinking a large spoiler will help you it will not. It will merely make you look like a poor ricer who lives in a trailer and has no idea what real downforce is about. Spoilers on FWD cars are merely for show, except at exceptionally high speeds where the back of the car begins to lift off the ground. I heard this is speed is around 100-130mph, maybe higher. And in a ga16de, you would have to be driving WOT for about 5 miles to get your car up to 100mph, if it is even possible for one to go that high. An se-r, however...

ju§tin
96 se-r


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## PatScottAKA99XE (Apr 30, 2002)

SXSENIS,
An OEM spoiler creating d-force...where did you hear that? The rear window on a Sentra is too steep for air to smoothly flow down to a OEM(read:short) spoiler. A tall wing would really act SOONER than a short one, not later. Yes FWD cars need front d-force(or reduced lift), most cars have front lift problems at high speed. Wider tires wouldnt help as much as you think becasue they are being lifted off the ground. A better aero package would be a better choice for other reasons as well(bigger tires=slower car due to weight, and more unsprung weight as well)

Crono1321,
The purpose of a spoiler is not to make the wheels "spin harder"(whatever that means?). The real reasons are: stability,traction/grip(lateral), and in some cases reduced(yes, reduced) drag. A big sterio would not do this. It would upset the car a low speeds where a wing would not. If you get a wing that reduces(again yes,reduces) drag, it would not slow you down. The oppisite would be true(better gas milage as well). For show you say..look at the pic below. You dont put a drag inducing item on a real race car for show. At high speeds, yeah thats where I want it, 100mph+. I am not going to drive around town with it on. BTW it doest not take my GA 5 miles at WOT to hit 100mph  . Oh yeah...I have a SR20DET planned for my car after the suspension,and brakes are done. 100mph will only be a throttle crack away.

Please guys(not just you two) dont scream a ricer if you do not know the circumstances. To me or anyone else.


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## Sr20kidD (Apr 30, 2002)

morepower2 said:


> *
> 
> That is not true at all!
> 
> Mike *




mike i want your brackets and and your wing. hehe


is the nismo wing that they have on the silver specV the same as the one you have by fiber images??


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## Crono1321 (Jun 8, 2002)

By spinning the wheels harder..ahhh (!!!) its hard to explain. You sort of wrote it out in your post. Basically by adding more weight/downforce, you can increase the pressure (am I using the right words lol its hard to understand I need an illustration). I know weight distribution is key as well, but from what I have learned you should have more weight in the back/trunk of your car if you want your wheels to grip better (?? I Know, just don't try to understand  ). Basically, weight=wheels down=better traction=better torque/horsepower coming from your wheels. Am I correct? I am sorry my vocabulary seems to be quite limited tonight, therefore I can't seem to make a...competent explanation. And about the GA I was only kidding..you get up to 100 in 2 miles!!!  Don't flame me! PLEASE! LoL Production on these DET motors should be up, all the GXE owners in the world are buying them these days  Again, don't flame me! 

Also, if you can offer me some suggestions on where to correct these theories...thanks.

Ju§tin


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## Crono1321 (Jun 8, 2002)

And please tell me that car in the picture isn't a ga16...


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## PatScottAKA99XE (Apr 30, 2002)

Crono1321, weight does not equal d-force. Example...one time i was headed to shcool with my toolbox(about 150lbs.) in the trunk of my car. On one on-ramp the rear of my car slid out of line quite a ways. A wing would not cause this, it would prevent it. Do you see the difference? Rear wieght=oversteer, rear down force prevents it. Now I am talking about in the corners. Your theory would work in a straight line. In a drag race(RWD car) the weight would help rear traction all the way from the start, but making you slower overall. The wing would only help grip once you are at a speed that would make it effective,but it would take one hell of a motor to need that wing to prevent wheel slip at such a speed, but it would not maker you as slow as the wieght would. The d-force I want is for cornering reasons and high speed stability. Weight on one end of the car would be a bad thing for me(I can feel the difference my subs make big time,of course those would not be in the car under race situations). 2 miles you think, nope even quicker. About DET production numbers...I am not buying a DET, I am building a 300WHP low compresion turbo DE. BTW I have an XE, less weight than a GXE. LOL... I am not flamin ya, jsut trying to help ya out.


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## SXSENIS (Jun 9, 2002)

*stillen*

stillen and motor trend both say the oem spoiler add moterate down force at highway speeds...stillens type II wing at 45mph..wider not larger meaning increasing the width and decreasing the side wall hight...maybe a 1 lbs. differance not enough to matter..and you will gain more traction and a wider foot print into corners were are front wheel drive cars will and i speak from experince slide the azz end around on you possible losing control completly and taking out a fence and winding up in a pond side veiw mirror deep...that's all i was sugesting not it would help with down force..just maybe another alternative to the fact there is no actual wing that could supply f1 type force to the rear of are cars...including se-r's..and hight has nothing to do with it its the angle of the wing that control when the force is effective..but no harm no foul..

motor trends test of stillen's se-r sentra and the 95 review of the 200sx se-r..{same spoiler same effect}


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## Crono1321 (Jun 8, 2002)

Of course your car will like to fish tail if you have more weight in the back than the front. For the whole weight thing, I was talking about RWD cars, and those variable 4WD cars. When we were discussing this I thought we were talking about a straight line. I believe if you are going to be doing many turns and such that equal weight in the front and back would be recommended. I agree with you, my subs slow my car down, and sometimes I get angry with all 100+ lbs. of it!  And also...in a drag race, wouldn't getting a good start outweigh the extra weight problems you would face once both cars have started? In a 1/4 mile, most of these *good* races are over in less than 13-15 seconds, possibly quite a bit less. I know that some of those super fast cars with the spoilers that go like 10 feet in the air...their 1/4 miles are over in what...like 5 seconds? Of course, these cars don't have a trunk to put weight in .. AHH getting off topic. Anyway, what I am saying is..if you are going to be racing from a stop the weight will help you. Now if you are like in..Le Mans and whatnot on a long track, then this weight might cause you to lose this race. Also, its ok I know that an XE is kind of fast (??)...my friend has one I beat a GS eclipse in one! Stock too! But let us not get on a topic of racing. Also, I'm intrigued..are you keeping the GA16 and just making it a turbo? Or are you putting in an sr20? Hmm.

Ju§tin


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## PatScottAKA99XE (Apr 30, 2002)

SXSENIS,

Brush up on your aero theory. Heigth does matter. Our rear windows are too steep for air to get to a short spoiler. The air that does get there is very dirty. If you raise the height, it gets the spoiler into the clean air making it work right.


Crono1321,

I dont really know if the traction you would get from weight would out-weigh the penilties. I dont drag race so I am not all that interested. It is a good theroy none the less. As for an XE being fast.. faster than the other GA powered trim levels anyways.LOL My engine plans...SR20DE, built with lower compression and a turbo, plus lots of other stuff that I wont waste space here describing. It whould be good for well over 300 wheel hp.


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## Crono1321 (Jun 8, 2002)

Thank you for complementing and accepting my theory . Although I'm not a drag racer myself, I have taken physics over the past year, and coupled with my knowledge of cars, I just made that theory, along with listening to people's experiences. I am confused though on your plans for your car, I get the sr20 swap including turbo, but what confuses me is the lower compression you want. I am rather ignorant when it comes to working on the engine block, and I thought that higher compression was better??? Is lower compression better for forced induction? Please, tell me about your plans. I am very interested in anything performance wise, as you see I am still in the point where I can do much to my car. Either post it here on the forum, or email me or IM me whichever is fine. I just have a craving for knowledge, that's all. 

Ju§tin


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## PatScottAKA99XE (Apr 30, 2002)

Crono1321,
You welcome. I wont waste space here with my plans, but if you go here http://www.nissanforums.com/showthread.php?s=&threadid=1252 You will see about the low compression thing.


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## SXSENIS (Jun 9, 2002)

if height dos matter so mutch why does 911 and m5 have such short soilers with a step angle..they dont stick 3ft in the air..the bmw's dont even have a 3inches of trunk clearance..the air still travels down the glass it might not be as smooth as other high dallor designs but the co-efficient drag is still farly low compared to a jetta or brick wall on wheels...if you noticed i said the type II
wing from stillen is better at suppling down force..its taller but not gawdy like thoughs non working hi boy wings you see on saturns, civics, and other popular cars...i was just meaning some not all after market wing dont do what they are intended to do..I mean dont get me wrong there are some good looking spoilers that work..I prefer the aluminum single level ones.. they'd look good on my 200 but i really dont need it"maybe 8 to 10 inches off the deck lid"..oh by the way i work at a machine shop and we have several cadd programs one has a auto design section that gives the co-eff. drag of cars, ect..I've gotten chewed a couple of times for playing and not working..trust me i have experimented[?] with everything i could think of, and the jetta just beat the wall on wheels


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## PatScottAKA99XE (Apr 30, 2002)

SXSENIS ,

Just because an expensive car has a wing does not mean that it is effective. Short wings do have a purpose and most of the time it is not D-force, short wings when designed right can lower a cars drag and increase stability(having nill effects on D-force). This is the main reason expensive cars have them, not nessesarily for D-force.


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## tekamadrid (Jul 24, 2006)

ok... i have to say one thing about F1 cars. those cars' entire bodies are designed to control the airflow around the car. downforce does not neccesarily increase drag, especially since they do have that venturi effect on the car. now... the reason the venturi works so well is that there is an amazing increase in the volume of the airflow at the rear of the car, which produces suction and since the amount of air coming into the front of the venturi does not satisfy the increase in suction, there is a resultant negative pressure in the underside of the car that creates "downforce". on a B14, you wil NEVER be able to produce that amount of downforce, period. so my question to you is Why do you want more downforce? What is your ultimate goal that you plan to achieve by increasing the downforce, and where are you going to use it?


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## Sentrixx (Apr 30, 2002)

JESUS!!!! Talk about bring a dead thread back... My god. I havn't gotten a post back from this thread in 3 years!


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## zachmccool (Mar 7, 2005)

Just a question How all on here are Studding or have studied Aerospace Engineering? If you have not studied it at a acreaded college then you need to keep you moth shut on issues like this. 

Eny way's i think a OEM rear spooler will do you just fine. My 200sx dose great with one on it and i would be afraid to remove it. But like stated before it would only help above 70mph or so. Over 100 and it will really make a difference. It wont put down force on the front end but it will help keep the car form "floating around", if you know what i mean.

eny way's just my 2cents.


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## morepower2 (Apr 19, 2002)

zachmccool said:


> Just a question How all on here are Studding or have studied Aerospace Engineering? If you have not studied it at a acreaded college then you need to keep you moth shut on issues like this.


Maybe you might listen to yourself


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## zachmccool (Mar 7, 2005)

Actuly i am going to study aerospace engineering starting this fall. so i gess you'r kind of right, but then agine..... o never mind.


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