I've only built one car so it doesn't make me an expert in chassis building nor aerodynamics. whats the proper way to set up a rear spoiler a for a FWD car and how does it work. What's the benefit of having one oppose to not having one.. I need some feedback from the guys in here that have built RWD.. thanks..

 

i thought they were for downforce, to keep the rear from getting loose. but i don't know ****.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rota92 &raquo;</TD></TR><TR><TD CLASS="quote">As I'm sure you know, it must be to help rid of any negative pressure cavities behind the car lowering the coef. of drag right?</TD></TR></TABLE>

im thinkin maybe a duckbill on a civic hatch might do something to that effect.

a massive park bench on the back of a coupe though...aside from possibly tuning it to help you around a road course at high speeds, i cant imagine there are any benefits of having it on the back of a FWD car for drag racing.

this is my 'logic', i dont have any true factual input for you

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rota92 &raquo;</TD></TR><TR><TD CLASS="quote">As I'm sure you know, it must be to help rid of any negative pressure cavities behind the car lowering the coef. of drag right?</TD></TR></TABLE>

Thats what im unsure about myself.. what is it actually doing at 120mp 130mph vs 170mph better yet is there any literature on affects of drag spoilers in general and what it 's going on a RWD car if i could understand that i could apply it ..

 

prostock style wings are mainly to manipulate a long package for stability. the more narrow and longer your chassis is the better for aerodynamics.

now, where it really comes into play , i dont know i would guess around 140 to see any difference.

 

Not sure, but you dont want the wing to create downforce. If your planting the *** the nose will unload and lose traction.....obviously this is not good for us fwd guys. I've had a customer who drag races often and is pretty consistent tell me he gained 2 mph by going from a spoon style duckbill back to the oem----or in his case a jdm oem.

 

I do believe Leslie Durst Armendariz and her Crew/Scion have some info on this actually, maybe she will chime in here in a few

 

yeah i notice that her lid is flat with out lip or angle on the end.. would that be the ideal setup... so that air flow threw the spoiler without and restriction witch i think will help keep the car in a groove without creating too much down force to slow the car down.. what do you guys think?

 

it looks like it does have a slight lip on it.. Leslie where you at?

 

imo, the " wing " with the side plates, will make the car want to go straighter @ high speeds. the angle is slightly adjustable(the main part of the wing im talking about) ive seen Gardella's wing angled downward on his hotrod cobalt(when he was driving it) and now this year it seems to come straighter off the car with Jamie driving. im not real sure what this would do to the air stream coming off from the top and the bottom of the car though.






Modified by DaveF at 8:02 AM 9/11/2007


Modified by DaveF at 8:06 AM 9/11/2007

 

Get Coleman (nor cal member) to post the pic's of his spoiler on his DELSOL, Cleanest one' i seen so far

 

you are kidding right ?

 

This should be good.....

 

I had a OEM wing on my 93 rx7 and i picked up about 2 mph by takeing it off. Now the car felt a little looser on the top end but I think for all purposes you don't want something pokeing up disturbeing air flow maybe something that just goes with body lines helping smooth air flow out... that is just my E-theory

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SFWDcoupe &raquo;</TD></TR><TR><TD CLASS="quote">Get Coleman (nor cal member) to post the pic's of his spoiler on his DELSOL, Cleanest one' i seen so far</TD></TR></TABLE>

maybe you didnt notice that Steves wing looks almost stock (as far as curvature).. Come on lets see Colemans wing

 

 

imagine your car from the side. imagine its an eg hatchback. as your eg hatchback slides through the air the air goes around it in all directions.

a tear drop (in terms of drag) is a perfect shape aerodynamically. if a tear drop is driving through the air the air hits the broad side of it, moves around the outside of the teardrop and then it follows the contour of the teardrop and ultimately all of teh air neatly comes back together at the rear point of the teardrop. the rear of the tear drop is the reason for its low coefficient of drag. when the air can smoothly transition back to its normal position that it was sitting at before the teardrop plowed through it, less drag is created. (bare with my simplified explanations.)

a good example of this is the honda insight. it has a very low coefficient of drag. one of the major contributing factors for this is that the rear of teh vehicle progressively narrows. not as much as the tear drop but certainly to a noticeable degree.

so what happens on a shape (in this case a car) that doesnt have a rear end that progressively narrows and therefore doesnt enable the air to neatly come back to its undisturbed state?

well, its juts like when you drive a boat through water. if its a triangle shaped boat (like most speed boats) the rear end is flat. teh front end moves the water gently aside and then once teh water gets to teh rear portion and hits teh sudden "drop off" it spirals inward toward the empty space left behind the boat and this creates wake. a canoe would be more like the honda insight only to a larger degree, and it therefore creates little wake.

cars are the same way only the car is fully submerged so teh wake rushes in from all directions.

the benefit of having a rear spoiler on a honda civic drag car(spoiler meaning that teh leading edge sits flush with the body panel it attaches to unlike a wing where the leading edge is in a free stream of air) is that it gives the air a few more feet or inches of travel before it :drops off" the back of teh car causing wake. this relocates the point at which the wake begins at some point further away from the rear of the car and this reduces drag.

now what i just said is only referring to the flush mounted rear spoilers that simply exntend outward from the roofline.

if you are talking about spoilers with an aggressive angle of attack or actual aerofoils i would reccommend not installing them on your drag car unless you have a real issue with rear stability, in which case i would suggest that build a nice front air dam first and then see if you need a rear wing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by six sigma racing &raquo;</TD></TR><TR><TD CLASS="quote">

it looks like it does have a slight lip on it.. Leslie where you at?</TD></TR></TABLE>


Yeah Danny it does have a very slight lip.... I don't have very much info for you on why it was built that way. You really need to talk to Gary Steen @ Steen Chassis for more info on the design....

 

Never mind - you already have this. Bad scroll button, bad!

Still, Good luck and hope to see you in Pomona or Bakersfield!!!!


Modified by dlcracing at 2:53 PM 9/11/2007

 

Thanks for the input Daniel i read it right before you took it down..

 

Tony gave me a good idea.. Told me to run the car for a few races get it consistant add a spoiler and see what i does .. So i guess ill update this tread in a few month..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by six sigma racing &raquo;</TD></TR><TR><TD CLASS="quote">Tony gave me a good idea.. Told me to run the car for a few races get it consistant add a spoiler and see what i does .. So i guess ill update this tread in a few month..</TD></TR></TABLE>


Why not add the spoiler and at the same test session take it off when you know the conditions are the exact same or as close as possible? I dunno how many runs you guys get out at a Test N Tune out there but here lately the track has been good at getting lots of runs in

Get it consistent first of course then after that add it and then take it off

Maybe you can sneak into one of the GM Team's Wind Tunnel testing

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed.com &raquo;</TD></TR><TR><TD CLASS="quote">
Maybe you can sneak into one of the GM Team's Wind Tunnel testing </TD></TR></TABLE>

Good luck, but I would actually like to know more about aero myself! I understand a bit, but there is always more to learn!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed.com &raquo;</TD></TR><TR><TD CLASS="quote">


Maybe you can sneak into one of the GM Team's Wind Tunnel testing </TD></TR></TABLE>

we have a cheap wind tunnel in NC (the same tunnel Hod Rod magazine used on their record setting landspeed camaro)

FIRST-VISIT Pricing:

$345 per hour for the First 2 Hours

REGULAR Pricing:

$490 per hour (2 hour minimum)


*edit*

http://www.a2wt.com/