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Wing or diffuser?

Old 06-04-12, 06:02 AM
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Wing or diffuser?

Hi guys

I'm trying to work out what's the next step in aero development for the race car, which is going to have the biggest impact - make the car faster!

I've got a splitter and flat under tray (back to the sway bar) at the front, matching side skirts, although nothing flat extending into the middle of the car from the bottom of the skirt...

It seems like the next step is either a GT style wing or a diffuser.

What do you think?

Thanks
Shaun
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Old 06-04-12, 06:10 AM
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oops - this time with a photo...
Attached Thumbnails Wing or diffuser?-utrs-r2.6.jpg  
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Old 06-04-12, 07:25 AM
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Wing first. It's adjustable, LOWERS weight, and won't get damaged in an off-track excursion.

Some canards on the front, if they're legal in your class. Don't know just how much they help, but what the heck... couldn't hurt.
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Old 06-04-12, 08:09 AM
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usually the next best step is instruction...

When you say race car, do you mean HPDE car? If not you have left a lot of information out of your question.
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Old 06-04-12, 08:10 AM
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Originally Posted by Valkyrie View Post
Wing first. It's adjustable, LOWERS weight, and won't get damaged in an off-track excursion.

Some canards on the front, if they're legal in your class. Don't know just how much they help, but what the heck... couldn't hurt.


So much wrong here I dont know where to begin. The first is how does a wing lower weight exactly?
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Old 06-04-12, 08:40 AM
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Compared to the stock wing, obviously. Not by much though.
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Old 06-04-12, 08:47 AM
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Ok, so let me help you here-

First, by the time you add the hardware etc to mount a wing, you have likely not saved any weight. Even if you in fact did save weight, there is drag to consider, and you have to balance the reward/penalty of the drag vs downforce.

You can just bolt a wing on and go for a drive and maybe its better maybe its not, but it is far easier to screw up wing settings than get them right. FAR EASIER.
A wing does not in and of itself help you with putting power down on corner exit. It will(properly setup) enable you to have a higher cornering speed which leads to higher exit speed which in turn lowers laptimes. Higher exit speeds usually also helps with power delivery, but this is a long conversation.

Generically wings on club cars are grossly misused and definitely not understood. You will gain far more laptime through good instruction, a well adjusted and tuned suspension, and seat time than you will by throwing on an aero device.
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Old 06-04-12, 03:47 PM
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Stock R1 wing only weighs like 4 lbs since it is basically just a big piece of foam. As D Walker said, pretty much any aftermarket wing (good or bad) will add weight. From a bang for buck perspective, and given that you do not have complete underbody, my guess is the downforce from a wing will far outweigh what you'd get from a diffuser. I think there is alot more engineering that needs to go into a diffuser and it will be more dependent on the other parts it needs to work right.

-Andy
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Old 06-04-12, 04:18 PM
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Experience with a FD GT car. A wing added to the rear of the car within the rules was able to generate so much downforce it mde the car undrivable. Couldn't get the front to stick any where near as much as the rear even with the splitter.

Running without the wing tufts of yarn on the back window stand straight up in the air= lift and drag from air not staying attached to the body.

Running the wing at a neutral angle of attack it made the yarn lay down smooth and helped both top end and cornering.

My vote. Wing. Diffuser is very hard to make work as an add on to car without much overhang behind the wheels. They are also very touchy to ride height
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Old 06-04-12, 04:28 PM
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Just to add my $.02. First if you are going to add a wing to your car, you have to consider the effectiveness of the airfoil design versus the normal speeds you travel on your track. If your max speed, cornering speed, is under 100 mph/ 160 kmh, then no wing is really going to make a substantial difference when you compare it to the costs in added drag. If you are grossly overpowered, then you can set your wing damn near straight up and down, add a ton of drag and get some downforce in the rear. Just like sticking a sheet of plywood up in the air. Look at World of Outlaw sprint cars. Their wings are so inefficient, but they work as the cars have huge power and really don't go super fast. Most tracks in New Zealand have relatively slower corners as far as I know. I race at Mosport most of the time and aero does have an effect on most cars lap times.

Personally, I would take the rear wing off your car as I don't think it does a thing and its got to weigh a lot. Try a race or 2 like this and see if the reduced drag makes you go any faster in a straight line. Take the money that you were going to spend on a wing and put the stickiest tires you can get on the car and use that for improved mechanical grip which helps in cornering, braking and accelerating. Play with the rear toe and bar settings to dial out any corner entry transient oversteering spookiness and you will go way faster.

If you have your heart set on a wing, don't buy any over the counter Japanese tuner wing, get a WC or Grand Am Crawford Composite wing and mount it high enough in the airstream so it isn't shadowed by the greenhouse. They really work well on a variety of cars and have a huge bling factor. I an certain that a few guys in Kiwi land have started making clones. I know of a Cobra R runner down there with some good stuff that they have made in-country.

If you are going to add it, make sure it will do something or admit to yourself that you are adding it to look cool and try to minimize the impact on your cars performance.

Eric
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Old 06-04-12, 04:47 PM
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Get a kognition spoiler.
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Old 06-04-12, 04:52 PM
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diffusers also dont work nearly as well if the bottom of the car isnt flat leading up to it.

i also vote wing, but go with a proper low drag wing (not that APR bullshit...). kognition is a high DF wing which comes with a drag penalty. rear wing should only be used to balance the car, so theres realyl no need for an extreme wing unless your front end makes really good downforce. if you can find one, a NASCAR COT wing is actually a great profile for low drag/downforce. same as crawford, grandam, etc, except they're like $600 used.
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Old 06-05-12, 03:12 AM
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Originally Posted by D Walker View Post
usually the next best step is instruction...

When you say race car, do you mean HPDE car? If not you have left a lot of information out of your question.
I race in an open GT class down here in NZ, it's very open in terms of what you can do with the car, everyone is grouped based on lap times into 3 divisions.

The car is stripped of anything non-essential, has an extensive chrome moly cage in it and weighs in at 2425 lbs (incl 1/2 tank of gas, but no driver).

I'm running stock twins (non-seq) with a mild extend port done on the motor ... upgraded radiator, IC, oil coolers, fuel pumps and 4 850cc injectors.

I'll move to a single turbo next year (I'm watching Howard Coleman's thread with interest), but thought I might do the next bit of aero work in the meantime.
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Old 06-05-12, 03:23 AM
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Originally Posted by D Walker View Post

Generically wings on club cars are grossly misused and definitely not understood. You will gain far more laptime through good instruction, a well adjusted and tuned suspension, and seat time than you will by throwing on an aero device.
Agree completely, I'm currently focussing on alignment, suspension set-up and seat time, along with many hours watching footage taken from inside the car to review where I can improve ... there's not a lot of instruction options near where I live ...
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Old 06-05-12, 06:04 AM
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Originally Posted by jgrewe View Post
Experience with a FD GT car. A wing added to the rear of the car within the rules was able to generate so much downforce it mde the car undrivable. Couldn't get the front to stick any where near as much as the rear even with the splitter.

Running without the wing tufts of yarn on the back window stand straight up in the air= lift and drag from air not staying attached to the body.

Running the wing at a neutral angle of attack it made the yarn lay down smooth and helped both top end and cornering.
Great idea - I will do some testing with the tufts of yarn and confirm how bad/good my current set-up is.

How did you record what was happening? Mount a Go-Pro facing backwards on the roof filming the rear windscreen?
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Old 06-05-12, 10:02 AM
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Autospeed Magazine LINK has done a lot of nice DIY aero testing, some of it even involving FDs. Using vortex generators, they were able to smooth out the airflow over the stock wing more effectively for relatively cheap. Might be a good first step before making a big purchase like a high end wing. Do some digging and search around their site for "aero" and "vortex"
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