S4 Playin w/u

According to that link you guys posted, it looks like Mr. Buschur already tested it and found no gains whatsoever. Just as I thought.

ShiftySVT

You're confused about the difference between weight (mass x gravity) and down-force.

Adding weight slows the acceleration of the car because
Acceleration = Force/Mass

Adding down-force slows acceleration because of aerodynamic drag, which is a force that opposes forward motion. This force is proportional to the square of speed.

Clearly these are two completely unrelated phenomena, so please don't confuse them and tell people they can shave 2-3 tenths by removing their wing.

TrinaBabe

iTrader: (3)

At 118 it may not make a difference... at 130 it may be huge. Not trying to say anything about what Buschur wrote but considering his drag car does not have one and he claimed if anything the car was "ever so slightly slower" without it.... makes me think twice.

Also, if you look at all the fast Evos (Curt's, Dave's, Al's, Dan's, AMS's, etc...) not one of them still has the wing. There is a reason... its not for the 7 lb weight savings I really doubt

S4 Playin w/u

LOL, I knew somebody would say that... You think if it makes no difference at 118, it could make a huge difference at 130? Even if it DID start to make a difference at 130, you're forgetting that the run ENDS at that speed... Plus, we're talking about only 12mph here... On a 130mph trap car, that 12mph represents only a couple hundred feet worth of acceleration... You could have an Evo's aerodynamics for the first 118mph and then a brick-like car such as an old Fox Body Mustang for the remaining 12mph and I still doubt it would make much of a difference... Probably still less than 1mph and that is a much bigger aerodynamic difference than just having a wing on or off the Evo.

It shouldn't be that difficult to test this out yourself at the strip. You could do some A-B, A-B tests at the dragstrip and take the average of the trap speeds with the wing on vs the average of the trap speeds with the wing off. This would be about the most conclusive way of testing it outside of say maybe running your car through a wind tunnel (yea, good luck with that!)

7lbs of weight savings in itself is quite meaningless, but when done with lots of other little things it can quickly add up. Or maybe some of the cars you mentioned have carbon fiber trunklids and they didn't feel like drilling holes for the wing so they said screw it, we'll just keep it off. Or maybe they did it in attempt to make their cars stick out more from the other Evos at the events since most Evos run WITH the wing... Lots of possibilities here.

TrinaBabe

iTrader: (3)

Well no, the whole help the car stick out from others.. lets be honest. They are all race cars from shops (Aside from Curts which is still a race car). So they arent worried about trying to make it look different. Some of them are RS's so I could see not bothering to get a wing for it. But it seems pretty damned strange to me that EVERY fast one doesnt have it

And about it not making a difference at 118 but it might at 130.. Im not great at physics but I would say the drag is exponential to the speed... at 10 to 20 mph the difference might be minute but at 50-60 is may be much greater, at 120 to 130 even more so a difference. Im not sure but it seems like it might be. Oh, and I never said it didnt make a difference at 118.. someone else did I personally believe it does make a difference... the problem is at lower traps it may not be as noticable... people arent consistant enough to hit 118.6 every run so if it only helped by .5 mph people would probably never notice. Now if it makes a 1-2 mph difference it would be noticable.

I will do back to back testing on it and I honestly do think its worth a mph or two. I could be completely wrong. Now I have another clutch/tranny problem so I may not make it this weekend to the track but when I do Ill test it out

DragNRacing

iTrader: (1)

Opposite end of the car but I once ran my GSX with my hood off for a few races(because I was stupid and forgot to lock the hood pins...ever have a sunroof explode on top of your head?...sucks digging glass chunks out of your skull). The fastest times I ever ran were with the hood off the car. It didn't make sense to me at the time as drag should have been effected greatly. Maybe it acted like ram air somehow.

TrinaBabe

iTrader: (3)

ok well I need some help with a physics guy now

Does downforce effect acceleration/top speed?

I know drag does which is a side effect of a wing but does the actual downforce make the car slower (In effect weighing the car down more I assume it does).

I found some specs from Mitsu about the downforce that various things create... Ralliart front canards (2) = 4 kfg of downforce @ roughly 110 mph. The small tape on lip on the top of the spoiler (NOT the spoiler itself) also creates roughly 4 KGF of downforce at 110 mph.

Now from what I have read, the downforce does effect acceleration by effectively making the object "weigh" more at higher speeds. Same idea as pushing a chunk of metal across a table... push a 1lb chunk of steel striaght... now add another lb of weight to it and push again.

I am pretty sure this is the correct way to look at this but someone that knows physics better would know more. The only thing I can see that the wing actually helps with is making the car have less drag... even though it is a big wing, it is disrupting the airflow coming from the roof of the car helping enlongate the wind path flowing over the car. I would guess the downforce (Unknown right now... I would guess in the area of 50-75 lbs starting at 100 mph going up to 70-150 lbs at 130 mph. I dont think the decrease in drag (If there truly would be any... it could make the drag worse) would be able to countereffect the increase of weight.

Considering most cars trapping at 127 and higher hit over 100 by the 1/8th it would mean for half the track they are adding 50-150 lbs of weight... this seems relatively significant to me.

From what I think (Which may be wrong) it seems the best overall way would be to toss the wing and add the vortex generator... the vortex generator would help reduce drag but wouldnt make any more downforce without a wing. Removing the wing would only remove the downforce. Seems like a simple way to cut 100lbs or more off the car to me.

I will try to find some more info about this stuff but this seems pretty logical to me. Alot of math is needed to guestimate what you could test in 20 seconds I wish my car was running!

scorke

iTrader: (18)

Yes, the more downforce the slower the top speed, more downforce=more rolling resistance between the tires and the road. The wing's downforce doesnt really come into effect until you are over 70mph or so. Removing the wing is definately a good idea if your serious about drag racing but it wont make much of a difference.

Scorke

TrinaBabe

iTrader: (3)

...

1.8t

iTrader: (16)

What you need is Shaun@SG or Saabtuner to come in here and do their tengo about the physics. One things for sure, a very in depth answer would come from their discussion.

A418t81

iTrader: (5)

I personally am tired of reading reviews on basic college level fluid dynamics topics.

TrinaBabe

iTrader: (3)

Thanks for the info.

By the way, I am trying to find the formulas of how downforce effects it, not just a guestimate but the actual formula. Is it the same as adding weight to the car or not? I am also trying to figure out how much downforce would be created (And drag) at different speeds. I believe it is the square root of the speed which effects it but Im not sure.

A418t81

iTrader: (5)

Not sure what is going on here, but my post you quoted Trina wasn't aimed at you, but rather a response to 1.8T about others who feel the need to continually rehash basic physics on an evo board

TrinaBabe

iTrader: (3)

Mine was aimed at all those people making posts about how to launch thier car, how much hp they should make, how to swap a fuel pump, etc... Not aimed at you


On to the topic at hand I just finally thought of something.... our wings are designed to create downforce obviously. The question here is how much force and how much drag is created from it. I used to think the downforce would be considerable but thinking about it again makes me re-think it all. If it had too much downforce, it would squat the rear of the car, lifting the front. This would obviously not be a safe maneuver unless the front had close to equal the amount of downforce (Which I doubt would be possible without any type of canards or more underbody panelling).

I believe the best outcome would be to use the VGs that come on the MR to help keep the velocity as high as possible and swap the wing for a simple spoiler instead. The spoiler would be designed to increase the Cd but not induce nearly as much downforce. This would also be the best for reducing drag.

Another big spot where I think the car could gain some aero help is the underside. Specifically near the rear bumper area. Since i have removed all the evap and bumper support stuff it is kinda like a parachute back there. I would think plating that up could help a ton. I would think some sort of channeling would also help increase the velocity of air traveling underneath the vehicle effectively reducing lift and drag.

I hate benchracing

TrinaBabe

iTrader: (3)

Doesnt anyone on here have access to a wind tunnel