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Author Topic:   rear spoiler
akadirtracer7
Dirt Freak

Total posts: 217
posted May 26, 2004 08:58 PM  
I see the pictures and alot of you have rear spoilers.What angle do you set them at?whats to much and whats not enough.I'm getting ready to try one and I was wondering what is the recomended starting point.

racer17j
Dirt Forum Champ
Total posts: 5390
posted May 26, 2004 09:10 PM  
first off how many of you think a spoiler actually works /helps?

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted May 27, 2004 03:50 PM  
As far as whether they work it depends on the car they are on. Late models yes, mods maybe, stocks i really doubt it but you never know. It seems on our mod the biggest thing the spoiler did was keep people from sitting on the back of the car...

way2fast72
Dirt Freak

Total posts: 303
posted May 27, 2004 05:29 PM  
I agree,they look cool,but functional? I doubt it.if your running 100 mph plus then yeah maybe.

Leadfoot#8
Dirt Full Roller

Total posts: 44
posted May 27, 2004 07:46 PM  
Mine probably doesn't put down any downforce==LOL==but it sure looks good===came off of a Toyota MR2

outlawstock17
Dirt Forum Champ
Total posts: 1363
posted May 27, 2004 09:12 PM  
i've said this before......if you don't think a rear spoiler creates downforce, cut an 8"x60" piece of plywood and hold it at a 45 degree angle standing in the back of your buddy's truck while he drives down the road increasing his speed up to your racing speed. better yet, do this while standing on a bathroom scale. rear spoilers create downforce, even at relatively low speeds.

akadirtracer7
Dirt Freak

Total posts: 217
posted May 27, 2004 09:19 PM  
Wondered the same thing myself but yea we do get up to 100 mph.Its a big track 9/16 with long straights and banked turns.

waltonjr1
Dirt Forum Champ
Total posts: 516
posted May 27, 2004 10:54 PM  


 
Dont know if they work or not but it gives the car a tough look.


ryan
Dirt Forum Champ
Total posts: 776
posted May 28, 2004 09:14 PM  
If its tall enough it keeps people from tailgating. lol
We can run up to 8 inch.


[This message has been edited by ryan (edited May 28, 2004).]

akadirtracer7
Dirt Freak

Total posts: 217
posted May 29, 2004 12:44 AM  
well the spoiler made a difference I run my 3300 lb factory stock put headers and 8 " spoiler at 45* (thanks 17j) and had to run with the limited late models and didn't do to bad.I got a fourth out o seven in the heat and 5th out of fourteen in the feature,I don't think I can complain about that.The car was loose going in before the spoiler ,after putting the spoiler on it was tight going in should be able to do something for that.

dtd_93
Dirt Maniac

Total posts: 132
posted May 29, 2004 11:37 AM  
was talk with a buddie about this subjet and like he told me put your hand out the window at 45 mph and you can feel it pushin it down...

UNVRNO
Dirt Maniac

Total posts: 136
posted May 29, 2004 01:48 PM  
60 degrees, and 90 degrees would be the more common options for spoiler angle, 45 would be on a very large track after the 60 was too much..

zeroracing
Dirt Forum Champ
Total posts: 1875
posted May 29, 2004 07:38 PM  
run a dodge superbird wing. that would work great... just joking.
rear spoliers will not make a huge difference on a street stock most the time, the cars are so un aero to begin with. also yeah it may seem like alot to your hand when you stick it out the window but compaired to what the car feels it is not huge. mods it is debateable, on short tracks it makes no difference either. on long tracks it is debated and makes small differences. the front tires screw up the aero on them.
late models yes makes a difference.
but as far as a street stock mainly for looks on most tracks. but i would start at 45 and leave it alone. there are a hundred more important tuning aids on the car to deal with, spring choice, rear %, wedge, stagger...
put on the spoiler and alot of the difference will be subconsionce(mispelled), if you believe it will make a difference it just may in your head. but i never could notice any difference in a street stock and little on a short track mod. but does imporve the look alot of both.
also it really wont hurt your car any so put it on for looks if nothing else, just dont expect it to be a magic bite fin.

19J
Dirt Freak

Total posts: 370
posted May 29, 2004 08:55 PM  
I see you all debating this. Both sides have good points. Think about this....

Find a strong wall(brick)... Run into with your body just take off running. (your all thinking im nuts lol) Find out how fast you can run first. Lets say 5 mph. Run into it and see what happens to you. You cant stop though just run right into it. You will most likely get hurt right?

Now get in a car with a speedo go 5 mph and hit the same wall the same way. Did the car in comparesion to you have more or less damage??

Point is which can hold more human body or a car? The car can resist more force so even though that wind can move your hand or the plywood wants to fly your not as strong as your car so it makes it seem like it does alot when it might not do so much at all on a full size car. Then you are talking about corner entry and it helping. Well i dont know how you all race but around here its called throw the car in the corner so you wouldnt do as much as you think due to the spoiler at the wrong angle. A spoiler is designed for down force when going straight not sliding sideways. Just my penny though. Sorry so long.

joetaylor
Dirt Forum Champ
Total posts: 640
posted May 31, 2004 07:53 AM  
I have read this post and thought I would try something befor I put my spoiler on I loaded my car on the trailer (open) I wired tied the shocks to see the travle on them with out the spoiler it only moved about 1/4" @ 55mph now I installed the spoiler and travled the same road and the ssame speed and it moved 1 1/4" @ 55mph so my guess is that it will be a big help

just readneck wind tunnel testing

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loose is fast & on the edge of out of control

UNVRNO
Dirt Maniac

Total posts: 136
posted May 31, 2004 08:32 AM  
66, I mean....UNVRNO...please don't start again...we will be going thru the same scenario we did before. We don't pick fights here.

jam

a ladder on top of my wagon dropped fuel mileage 5 mpg on a 2000 saturn on the freeway 200 miles.

[This message has been edited by jammin (edited May 31, 2004).]

Okie11m
Dirt Freak

Total posts: 287
posted May 31, 2004 09:30 AM  
If you have a full int. kit it might help, but I would have to say they look better then they work & make a nice place to put a saying on the back of your car!

zeroracing
Dirt Forum Champ
Total posts: 1875
posted May 31, 2004 09:38 AM  
those gaint plexiglass sides like an outlaw latemodel. that will help and look differnt.
just joking

akadirtracer7
Dirt Freak

Total posts: 217
posted May 31, 2004 10:25 AM  
you guys can argue all you want but I shaved close to 2 seconds off my lap times by putting a spoiler and a set of headers on.the car was more stable and rear was hooked good .we all know the headers didn't has anything to do with the stabilty or the rear being hooked good.Next week I'm going to be putting 10" tires on and some more rear stagger and hopefully that will help

carolinafast
Dirt Full Roller

Total posts: 72
posted May 31, 2004 12:10 PM  
2seconds or .2 seconds?????
where did you get that spoiler
we took a spoiler off a pavement street stock and gained .2

[This message has been edited by carolinafast (edited May 31, 2004).]

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted June 01, 2004 08:40 AM  
2 seconds? You've convinced yourself it will stick better so your driving it harder. A spoiler might help a tiny bit, but you're not gaining 2 seconds with one. At my track, 2 seconds is the differnce between a back marker and a feature winner.

The redneck wind tunnel is a great idea, but here's the problem. A NASCAR Nextel car generates about 1400 pounds of downforce with a hand built body. Assuming your rear springs average 200 pounds and the 1 inch travel was due soley to the spoiler, you're claming 400 pounds of downforce from that spoiler. Do we really believe a single strip of tin will do 1/3 the work of an entire hand built stock car body?

How much would we laugh if some one said their car picked up a 2 second push when they removed the nose?

Good debate, but spend your money on tires instead of cool looking spoilers.


zeroracing
Dirt Forum Champ
Total posts: 1875
posted June 01, 2004 09:00 AM  
my question about the redneck wind tunnel does this comepsate for the car bouncing from pot holes or small bumps on the road.
i can travel the same stretch 2 or 3 times and hita slightly different line adn sometimes the body may bounce alot.
i feel western auto17 is correct. that most of it was you thought it would do it so it did in your head. i was at a big racers thing and dale mcdowell was talking about how drivers made the same mistake about how the car was because they wanted it to be that way. so they were ignoring the problems and saying it was better.
yet again, spend your money and time on shocks springs, tires, wheels, more motor, and adjusting weight.
if the streets gained 2 seconds a lap by going with spoilers at our track i would feel bad, they would ba as fast or faster than a mod.
like i said before on most tracks you can not even tell a difference in a mod with a spoiler versus one without, some run them some dont and they all run about the same speed.
but good luck to you, also the headers probally made a ton biggerdifference than the spoiler did. if the spoiler made the difference for you wheater on your car or you feel better with it on, it does add to the look of the car if nothing else, so keep it on just dont play with the angle trying to find magic speed.
good luck

akadirtracer7
Dirt Freak

Total posts: 217
posted June 01, 2004 10:58 PM  
So my imagination is what made me run faster thats cool that was cheap I'll take more.At the 3rd week into the season of factory stock the inspectors told me my car was illeagal and that if I want to run I have to run with the limited lates .Sure the car has been leagal for the last 3 years but now its not.thought about parking it but 3 races wasn't enough for the year.no close tracks. so I thought I would try it and thats were the spoiler ? came up.Like you said I had to step up to. Changing some things on the car and the mind game ended up the best times I've run at this track And its cheap because a freind has an old super stock sitting around and has plenty of parts that are there to try.Just to have a good time this year.I finished 5th out of 14 in the a main ,I know its not a powerful feild but they have alot better equipment than me . The top 3-4 run away from everybody else I can run with the rest of them.Just to fill the need for speed and that class pays more too.

joetaylor
Dirt Forum Champ
Total posts: 640
posted June 02, 2004 07:24 AM  
zero this road that I went down is brand new and I wen't down and set the cruze now I did this more than one time and each time on average it was a 1" drop in the suspention so what ever you guys want to say I am currently looking for a real wind tunnel so no one can say any thing about about the redneck way

I am not trying to start any thing

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loose is fast & on the edge of out of control

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted June 02, 2004 07:53 AM  
Joe -

I am not lookin' for a fight either, I just like a good debate.

I don't doubt the suspension travled an inch. I just think it was some other variable. There are bumps on the road, truck springs, trailer springs and a million other variables befor you even get to the variables in the car.

What you have to consider is not whether the suspension moved, but why it moved. In my opinion, you cannot keep a straight face and claim that a spoiler bolted on the trunk of a street stock can develope 400 pounds of downforce at a measly 55 mph. Who knows, I could be wrong, but I just don't think the air moves cleanly enough around a street stock (with no windows or boxed in interior) to ever get to a spoiler.

I put one on my old car and it made zero difference and I was just like you guys, I convinced myself it would help a little. However, I had to admit it didn't.

I guess I would say if really want a spoiler, put it on, set it around 60 degrees and don't ever think about it again.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted June 02, 2004 08:55 AM  
i am not trying to start a fight either, was just worried about the varibles.
as far as finding a wind tunnel, if you have enough to pay for tunnel time get out of streets and go to nascar. but you may check a local highschool. our highschool had a scale model windtunnel then you could jsut build a scale model of the body out of wood. but it may give you somewhat accurate numbers or just show you the actuall amount of difference that a spoiler will give you. our highschool had one. it was not huge but still had wind and a computer hooked up.

carolinafast
Dirt Full Roller

Total posts: 72
posted June 02, 2004 06:02 PM  
lol!!!..this is one hot topic! i'm thinking about getting the local wino to get up in the truck bed with a 5" spoiler and a jug
wondet which one will knock him down???
just kidding..here's my opinion...if you want one by all means put it on...however
attention to the basics is still what will put out front,...ain't this fun?

kgofsttrnlft
Dirt Roller

Total posts: 16
posted June 02, 2004 09:13 PM  
Wellllll....awright, check this out.
A spoiler on my limited late model, body differences notwithstanding....
74 inches wide, 8 inches tall....that's 592 square inches of surface area. At 60 mph, assuming a pressure of...say...something conservative, 1/2 pound of pressure per square inch....that's 296 pounds of force, that's like havin' a fat woman sittin' on yer trunk lid. Come on guys, it ain't that hard.

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted June 03, 2004 07:40 AM  
A straight bodied late model with a boxed in interior and a massive 8x74 spoiler is a different story. That monster would make a difference.

ratracer10
Dirt Maniac

Total posts: 141
posted June 03, 2004 08:52 AM  
Look at it from this perspective. With a 3000 lbs car, every 30 lbs you add to the rear wheels is 1% more rear. Considering that the spoiler is as far behind the rear wheels as you can get helps even more. If you were adding ballast, any weight to the rear bumper would give more rear percent then adding above the axle. So it should take less then 30 lbs at the spoiler to get 30 lbs at the rear wheels.


As hard as it is to get rear percent in street stocks every little bit helps. Yes a spoiler on a street stock is not as efficient as a late model. However, if you can gain 2-3% for free on you rear percent (while in motion) how can you say it was a waste of time.

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- When in doubt, hit the gas.

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted June 03, 2004 09:50 AM  
Its a waste because you're spending money and time chasing aero issues on a street stock when you would better spend that time and money improving the mechanical grip. In a dirt street stock, mechanical grip is were races are won and lost.

If you want a spoiler because you think it looks cool, than more power to you.

waltonjr1
Dirt Forum Champ
Total posts: 516
posted June 03, 2004 11:24 AM  
It does not cost a great deal of money to make a spoiler. 15 bucks on lexan, and made the wings from left over interior sheetmetal. 1 hour to make, its not going to hurt you so if you like the way it looks just put one on and go racing, just dont be expecting a major difference.


ratracer10
Dirt Maniac

Total posts: 141
posted June 03, 2004 01:32 PM  
Yes, that is my point exactly, itís cheap and takes very little time to install and will give a slight increase in down force. How much time and money do all racers spend on trying to get that last little bit of an advantage?

No, your not going to add a spoiler to a street stock and all the sudden go out and win the late model feature and it wonít even turn a tail field street stock into a street feature winner. It will however give and advantage over an otherwise equal car. If the rules allow it seams foolish to give up any such simple gains. Any gain, no matter how small is still a gain.

Let me pose another question. If aero makes no difference at street stock speeds, why do auto manufactures spend so much time and money on the aero of street cars to improve gas mileage?

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted June 03, 2004 02:07 PM  
ratracer
aero does play a part in performance at street speeds but most street driven cars have a windshield and side windows, not a big open hole in the middle of the car to catch air and screw up airflow over or around the car. think of the inside of a street stock car like the open bed of a pickup, not very aerodynamic is it.

ratracer10
Dirt Maniac

Total posts: 141
posted June 03, 2004 02:35 PM  
The lack of windshield makes the spoiler even more effective, there is nothing in the way to block the airflow to it. Thatís why the height and shape of the greenhouse is so critical to cars with a windshield, so the air can flow up and back down to the spoiler.

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted June 03, 2004 03:09 PM  
This is a great argument, nobody's changing anybody's mind, so lets keep it going.

Here's why the windsheild argument doesn't work - when the air flows over a stock car with windows, it flows up the windsheild and accross the roof. After the roof, a low pressure zone is created which ***** the air right back down to the trunk and spoiler and BAM, you have downforce. In a car with no windsheild and no boxed in interior, the air flows into the interior and turns into a tornado. Its never really gonna get to the spoiler. Thats why the driver's compartment in a late model is so small, to keep the air moving straight back to the giant lexan spoiler.

You just can't duplicate that situation with a street stock.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted June 03, 2004 03:16 PM  
thats what i mean, a late model is all enclosed and a mod is somewhat enclosed or at least has a flat deck to keep air flowing back to the spoiler. The open interior of a street stock acts like the empty pickup bed and tailgate, catches air and prob to some exent slows the car down.

bob17
Dirt Roller

Total posts: 16
posted June 03, 2004 03:36 PM  
i've tried several diff combos in the past just looking for an advantage and hear is my opinion, if you have an otherwisae slow car you can do all the body and aerodynmic work you want but in the end your still gonna have a slow car, if you take a fast car with an aftermarket nose, fully tinned interior and a small street stock style spoiler and you pull all that stuff off your gonna still have a fast car. we run our ss with a full tin interior monte ss noses and only half a fire wall just the driver side is full from what i can tell from my experience with a full fire wall the air runs through the nose and hits the firewall and either goes up or down, by cutting out th pass side and tinnig the interior in you allow for the air to tunnel through the inside and out the back. this has been proved to me because last week my dad dropped a cylinder and all the oil pumped out t6he valve cover breather on the driver side from blow by all the oil ende up on the pass side of the car there was no oil on the driver side at all the whole tunnel of sheet metal is covered in 20 50 valvoline but none ended up on the fire wall itself so it wouyld seem that the air is be sucke d otu through the pass side and out the back which is also open. so i think from aerodynmic terms as long as you have a decent nose on the car and you do all thast you can to keep the air from being trapped in the car you should be doing okay, but it's not gonna make any miracles you still need more importantly a good motor handling etc just my 2 cents

dtd_93
Dirt Maniac

Total posts: 132
posted June 03, 2004 08:38 PM  
ok ya's wanna hear a good one...
last year i was runnin around in my heat race when the top pins for my truck lid pulled threw asnd the lid stood up like a 2 foot spoiler.. and well it helped commin off and goin in but was killed me at the top end of the straigh.. the motor was luggin i was in the car and well i didn;t have a clue as to why the car had no power at the top of the straight away but it; wouldn't spin the tires commin off...

akadirtracer7
Dirt Freak

Total posts: 217
posted June 03, 2004 10:08 PM  
WoW All I can say is try a car with and without and form your own opinion it was worth my time and 20 bucks.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted June 03, 2004 10:10 PM  
i dont feel that they help much if any.
but for a short amount of time and 20 bucks they are worth it because they make the car look alot better. almost any car looks 100% better with a spoiler onit.

TxHobby3
Dirt Roller

Total posts: 9
posted June 05, 2004 10:19 PM  
OK I guess I'll way in on this too. This is going to be long.
On any car, it will add downforce to some degree. How much? A wind tunnels is he only way to answer this question. Any other test will have to many variables (even the redenck wind tunnel.)
I'll Start with the redneck wind tunnel. Was there a headwind, tailwind, cross wind on any of your tests? What about traffic? Also, is that a constant 1" of travel, or is it an oscillation? Also is the car loaded on the trailer the same? ( could effect the pitch of the car.) Also did you measure travel of the trailer axles? ( They will take some of the force as well.) What about tire pressures? ( on the car and the trailer, tires also perform the function of spring and dampners.) Also the tow vehicle will increase the areodynamics of the trailered vehicle, therfore increasing the effectiveness of the spoiler. ( similar to drafting in nascar)
Now for on track tests. Now there are even more variable here. Was the track the same on all tests (wet, tack, dry, rough, slick?) Was the car running the same? What about atmospheric conditions? (Cool damp, hot dry, high, or low bar. pressure? these will all effect the horspower output.) Is the setup the same on the car for all tests? What were the winds at the track like? Where was the car running (Top of track, bottom, out front, in traffic, alone?)
These are just some of the major variable that are difficult ton control outside of a wind tunnel, there are many more minor vairables.
Another point to consider is, will the downforce created by the spoiler be enough to offset the drag created by it? More than likely not. On a short track, it is probable that the straight is the only place where the spoiler will create an effective down force, which is the point where you want the the least drag, and the down force has the lowest benefit.
Now with that said, if you like the way spoilers look, or just plain want one, put one on. Just don't devote alot of time to it, the effects of the suspension set up will far outway any benefit of a rear spoiler.

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Gas on it!

    

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