This is just a fantastic forum! Being quite the newb, forgive me if I'm on the wrong thread. I need some advise and I know that it'll be freely if not copiously given. I like it already!
We've got a '74 that, at the moment, is in pieces. It's a street/track (little more focus on the track) baby that is getting some minor additions to help with high speed stability. One is the addition of a rear wing. There are two choices. As you can see from the pics, it's not pretty but at this point that's not the point.
What do you think about aerodynamics/functionality and also aesthetics?
Don't have any advise on the spoilers vs wings just wanted to say...
I like the first one the most, I have been wanting to put just a lip spoiler on the back of mine. I think it all really depends on the overall look of your car.
But, be careful some of the wings can bend your decklid....
You're in the right place!
Regarding spoilers; personally
T
any aero device mounted down on the decklid or a wing that low will have no aero advantage. I had a 6" tall rear spoiler on my car and it was pointless (tho' it looked really cool ).
So, I would just pick whichever you like the looks of as it will be aesthetic only. Without any additional aero devices such as vortex generators across the rear of the decklid, any wing needs to 1) have an actual foil shape, and 2) be mounted within a couple of inches of the roof height. Slightly higher above the roof, the cleaner the air and benefit.
My wing after selling the spoiler
I have a wing it is functional and it doesn't bend the deck lid.
Niether of the ones posted in the pictures will have any effect on downforce or stability at speed.
Because if the vertical rear window the air is insanely dirty and scrambled. Only way to get air to a wing is put it up high or use vortex generators on the roof and the wing only needs to be half as high.
and a splitter is absolutely required with the use of a wing. I have tried the wing with no splitter DON'T DO IT !!!!!!!
is there an echo....echo....echo... haha. Hey Joe, I saw the post and was sure you would be one of the replies, so imagine how happy I was to get in a reply first
yeah, what he said that I said that he and I have probably said before.
I almost forgot again... the reason for the post
The Paddock is another forum here in 914World that has some great older threads with pics and discussions on the wing builds of both of those awesome 914s seen above. For sure the wing+splitter is going to give more downforce, but unless you got lots of HP planned you may want to run w/o either to reduce aero drag...just like the OG 914 factory GT race cars. Great to see more race projects!
I agree with all above - and welcome to 914world!!!
However, its your car man, do what you want and if I was choosing for you it would be the first one.
without a wing your car will spin off into space.
My car is 5 MPH faster with wing and air dam than without and a heck of a lot more stable. Also bumped MPG so it's really not a fluke. Real air foils don't need a huge angle of attack to be effective.
Yes this very same wing mounted on a civic hatch with 10 degrees of angle slowed his car down 7 MPH.
I run my wing about 2 or 3 degrees high speed 100 + and crank it up high for Autocross. It has lees effect under 60 MPH.
I think your wing has to be high.
But I would get the front planted before I add downforce to the back.
My free advise on vortex generators on a 914.....
When engineers put vortex generators on a surface they are ususally trying to get the airflow to stay attached (in an unfavorable condition).
The rear window of a 914 is less of an unfavorable condition and more of an impossible condition. I am unaware of any way to keep the airflow attached over the back deck of the 914 short of making a "fastback".
The vortex generators that got a buzz here before apparently were designed to cleanly separate the airflow from the surface much like a small spoiler will do. So while there may be some benefit, there is still not "good air" near the rear deck. I do not know if this type of vortex generator or a small spoiler would allow for lower wing, but it won't allow for a fuctional device near the deck.
I am not an aeronautical engineer so you were overcharged for this advice.
Check out this webpage http://www.cassidy-online.com/porsche914/aerodynamic_aids/index.html
So does anyone have any good pictures of how you made your splitters and attached them to your air dams?
cool. I guess I should just go buy some aluminium and do it.
It really won't make any difference in an autocross situation Jon. Only on the track do these ground effects really work wonders. On the track a splitter also needs to be balanced by a spoiler.
Ok, they will make a difference, if they're big enough. And if you are going fast enough. A little Al one that sticks out an inch or 2 won't do anything at those speeds (kind of like the things that are on alot of ricers), and you still need to balance it out.
Hey Joe
Could you please send me some pics of your air dam/ splitter so I can see what it looks like. I am crafty, but my father in law is the one who really knows how to work with composites. If I have a picture to show him what I need it will help greatly in making it.
Thanks.
IF I could come up with a 200 sq in wing at a resonable price.....that I knew worked & a splitter that didn't stick out past the front bumper.....same requirements as above, I'd go fer em'. I get airflow to the spoiler as is, but I'm not convinced that it does much good......there is a cool factor tho.
Attached image(s)
so the discussion is bringing up some good points - all aero stuff is very car and use dependent. So if you want to AX and have "high" speed oversteer ("high" being quoted as 55-70mph on larger courses is high for AX but not for an interstate hwy let alone road course) then you want a big, FAT wing (fat in foil shape) and will probably run a maximum angle (right near wing "stall") to get both a spoiler and wing effect. So first you add the wing, which tends to overshoot and create understeer. So now you start adding splitter to counteract that to the point of how you want the car to feel.
So my car had NASTY high speed oversteer (125+ mph sweeps at Willow Springs thru T8) with the V8 and 930 trans (both much heavier than stock stuff) but not necessarily low speed oversteer (I can use the go-pedal with all the power to get what I want). So the car was scary. I then went to a whole new car setup (tube chassis, etc) and also added a wing at that time. I have a short splitter because I wanted to tune the car to just a slight plow (At speed expectation of 150+ thru T8 I wanted a safe bit of plow). So if I had stayed in CA to try a longer splitter, at some point the car would have gotten neutral and I would have scaled back to be somewhat safe. That is why I recommend an adjustable splitter that you can slide back and forth to fine tune the front downforce to match the rear and get the driver feel you like (slight over, neutral or slight understeer). You tune the rear to the max downforce that doesn't drag mph down (unless the car is still unstable, then you go up to wing stall to fix that issue even if it slows the car slightly).
I used to work with Tyson Schmidt, Wevo guy, when he lived in Seattle. My old boss goes down to see him about twice a year and they go to Willow. I think your 914 is the one they tell me about. They are very impressed, and they have some very nice 911's.
Phoenix - that may be. I never met Tyson tho' I know of him from guys that ran out there (he used to work on some of the 911s out there when he was in LA before going to WEVO) but he mentioned digging my car one time on the bird board. I never got to run the full tube car there with those guys tho' (I ran on a test and tune day about a month before moving to CO).
found this link about the COT splitter to give some of you guys ideas (maybe). Notice that pretty much exactly as Joe has done (and typically the rule of thumb), the splitter extends out about even with the bumper length. As stated, I started a bit shorter (which you can argue is stupid on my part as I could have easily removed material to a slight plow v. the impossible adding of mat'l - I don't always think everything completely thru hahahaha)
http://i.a.cnn.net/nascar/.element/img/1.0/sect/news/2007/1/22/cot/COT.pdf
Thanks for the link. That definately helps. I can make that.
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