Hi,

I've recently got into various track days and I've found my egg of a car just doesn't like high-speed straights. So I've arrived that a bit of aero could help settle the rear of the car a bit for those long straights or high speed sections of different tracks. Last year I made my first trip to VIR and I can say toping out 5th gear that much in my K-powered car made me realize how unstable the car felt at high speeds.

So I'm looking for suggestions, I've primarily been a drag car guy in my past, so aero just wasn't a huge concern.

I ordered a front splitter from Jeff @ Special Projects Racing last July...yet haven't heard on it, so I'm honestly open to any vendor as long as they can provide a product easily.

So front & rear options, I'm open to whatever is out there. I've noticed that various people have had custom pieces made, or using various Cwest parts, yet I just haven't been able to locate a reliable vendor.

Any help is welcomed,

as you can see, its stock CX appears, only piece I added was the VX underbody blockoff on the driver rear. The engine setup was originally built towards H1 spec, yet a mis-shift caused me to go with an illegal bottom end, so now its a lapping day car, until I opt to drop a stock block back in it.

 

Im in the same boat as you.

Thing to remember, is that proper flow of air under the car to increase velocity of flow is actualy more important then wings.
Downforce is created by velocity of air flow difference between air flowing under the car and flowing over the car. The faster the air flows under the car, the lower the pressure will be. Generating more downforce, which will help increase stability.

Another thing to consider is that the air meeting up behind the car needs to meeting up smoothly creating the least amount of pressure behind the car. Which will actually generate drag, if the tail end is to large (kinda like a parachute).

So with that being said, spend as much time on air flow under the car as much as you do over the top of the car.

Something I put together a while ago reguarding some aero stuff.

You want a very slight upward on the front of the splitter forcing some of the air to actually go under the car.
Mis understanding people have is that the pressure on the front is what causes the downforce..That actually causes drag.
Downforce comes from the pressure difference of the air on top vs the air below the wing(or car in this case).

You actually want to have NO pressure zone in front of the car, as it causes a high air pressure bubble to be created on the nose, forcing the car to push that bubble.
Optimal design would split the air gradually, forcing the air to slowly get pushed below or above the car.
However when adding a splitter to a car, you should also consider doing a rear diffuser. As just the splitter cases the balance of the pressure to be more front heavy. With an addition of the rear diffuser you are now not only able to balance it back out evenly, you will also create a smoother flow of air under the car allowing it to exit more efficiently. By having a diffuser you allow the air to now come together at a much faster rate, helping reduce the tail of the low pressure right behind the car. As the low pressure tail actually causes drag as well, similar to a parachute.

This image demonstrates the high pressure spot that is created in the front, along with different attack angles and how it effects it. As you can see its not a straigh cut, and more of a rounded leading edge.


Another image showing the high pressure spot, that causes the car to push a "air bubble" in the front.


And now a image of a F1 CFD. As you can see a F1 car has almost no vertical areas, as anything vertical will create drag.
Red shows the pressure being generated. The pressure generated is do to air flow below the wing and over the wing, and not pressure do to it raming into the air. When you put a splitter on with out re-directing the air, you are creating a huge pressure spot similar to what the tires are doing on the F1 car CFD
*perfect example of why you dont want air ramming into something is the front tires. As you can see it has allot of pressure in front of it.



This high pressure in front of the bumpers, is why Canards are installed on cars. The canards chanel the air thats in front of the car out ot the side where it typically would have a hard time moving itself. If you actually look at properley set up Canards, you will notice that they will start on the FRONT of the bumper and then move towards the side of the bumper. Chanelling the air that is trapped. As by moving the air you are eliminating that high pressure spot and are now increasing down force by moving the air.


And then Diffusers.
If you dont channel the air coming out from under the car, and air from over the car. You will get the air coliding, and cousing it to do all sorts of weird things. As you can see in this CFD of a lotus, there is a very low tail of pressure behind the car. Also you can see that the air is swirling as it comes out where the trunk is. This swirling causes the low pressure air to move out from that area. Making the car more smooth in flowing through the air

You actually want to create down force moving the air under and over the wing more efficentley, instead of creating drag by having huge pressure spots in front of the wings. And low pressure spots below. You want the air to flow over as smooth as you can, and exit as smooth as you can with cousing the least ammout of desurbance to the air. As the smoother the air the better the flow, the more down force, the less drag.


CN: When adding a front splitter. Also do a rear diffuser and air guides under the car along with over the car. Then add front Canards to chanel the air out of the high pressure spot in front of the car.

ps. sorry no spell check on the pc im using right now.

 

Found some cool wallpapers

 

I'll keep this open, but do search in the archives. I know for sure there are a few posts covering this EXACT topic.

It looks like you have the Spoon-type duckbill on the back, yes? There are a number of more aggressive wings available that might suit your needs, since you're asking specifically about rear-end stability.

snowman, can you elaborate on some points?
-Your mention of the splitter, followed by the diagram of what looks to me like a wing. Are you showing that as an ideal wing shape, or a splitter shape? I don't know how you could make a splitter to be shaped like that, if that is what you're trying to portray.

-How does the high pressure area relate to our car's need to have air flowing through the radiator, situated at the front of the car? Going by the F1 diagram you posted, the radiator outlets do indeed have some of the higher pressure areas. Is that just based on the necessity of a radiator being a big flat thing, or on the necessity of a radiator needing that type of air flow? If the latter, wouldn't some higher pressure flow right by the radiator be beneficial (from a cooling perspective) for a front-radiator car?

Also just a comment based on what I've seen: diffusers are very difficult to make work on a Civic/Integra. Short of cutting the crap out of the rear floor/bumper area, there's not a lot of room to work with there. From a racing standpoint (in the US) there is also not much room with respect to rules for a FWD car to develop that kind of thing.

I'm also curious as to why the aerodynamicist's we have here tend to have a flat "airdam" style bumper connection to a splitter, which directly opposes your idea. Not saying one or the other is wrong, just wondering the reason. It could very well be a degree of realism and practicality, rather than an ideal design (I have no idea), and that is something important to keep in mind, especially with our budget track cars.

While striving for the ideal is not something to be admonished for, you have to keep yourself grounded at the same time

 

The other thing to keep in mind with a rear wing is to get it into clean air with sufficient support to direct the downforce generated to the best place on the chassis. There is going to be a good bit of turbulence coming off the roof of the EG hb, so you will find that a properly designed wing will perform better if you can get it up and back (but if you go too far back, then you have to deal with downforce on the back of the car lifting the front of the car like a lever).

 

Hi guys sorry for the delay getting pictures up,,, I will show the wings i have made specifically for the Honda challenge cars. We have an EG running one now as well as the AEM car.

It was interesting how "little" wing was required for these chassis. Anything too large slowed the car down 2 seconds per lap. I had a post going a while back when I first tested the larger wing I designed. If our cars see too much rear wing it doesnt allow the car to transfer weight to the front and induces a push.

The fastest cars I have driven were "undriveable" without a wing. Anything short of that I could just tune out with suspension adjustments

 

^^pictures of said wings!

 

My current aero. My car changes from night and day without a front splitter and rear wing. I would say its almost undriveable under cornering with out aero.

P1 Spec V.1 Airdam + splitter.
PCI GT Wing Brackets w/ APR GT-U airfoil and PCI endplates.

 

I've done searchings, yet I see items like, there are better wings, but I never can find where to buy said wings.

As Made in OC posted, those are pretty much the aero mods I'd love to have. I ordered the v2 front splitter in July of 09 and I'm still on the list, or waiting for box to arrive. So at some point in time, I hope to have a front splitter, yet at the moment, I have nothing, so honestly anything at this point is better than nothing. I know the spoon type wing isn't doing me anything, but its something.

I have seen the various canards on cars, but I've always wondered how great they worked as you see the at so many various positions and angles. It seems for alot of hondas you see alot of airdams and splitters but there still isn't a large marketplace from what I've seen.

Really just looking for options out there.

I'm running 8041 race konis with 600f/800r with the ITR front sway bar and 24mm ASR rear bar. With the k20 upfront, its at 63/37 weight distribution sitting at 2200lbs with the fuel tank full without me, ITR conversion added some weight. Its tail happy and when I'm at putnam park, as I'm topping the 140mph mark at the end of the straight, I hit the brakes and the car literally jumps a bit as it settles down. I'm sure if I upped my nerve a bit, I could drive into turn 1 like that, but I feel a bit of aero can stable out the car and help my confidence.

Thanks again for the help.

 

Ill speak with Jeff to see why your airdam and splitter are taking such a long time... I generally help and work around his shop on the weekends so we'll see.

As far as the Canards, forget about it... Splitter and wing will do worlds of a difference. You probably wont notice a thing with Canards.

-Charles

 

Canards are secondary aero devices that work well, but at a somewhat lower efficiency than other parts such as the splitter/airdam, which is why I would develope them first. Flat splitters are good if they are properly designed and are the easiest to manufacture, but the best splitters in terms of efficient downforce production would have five or more diffusers built in to the underside of the part. Of course, the complexity of putting diffusers means that you'll have to understand how diffusers work and then you have make a composite mold and lay up each part. It is much easier to cut out a piece of plywood and mount it on the car to get maybe 75 to 80% of the downforce of a real aerodynamic splitter. In addition, you need to get the splitter height correct to minimize pitch sensitivity, avoid boundary layer blockage, and minimize underbody drag.

 

not to highjack but made in oc see what up because i have been trying to order one for my dc2 for a while and no luck

 

Like Charles stated, it is a significant difference to have a proper splitter and wing. It's been much more confidence inspiring and allowed me to feel more comfortable pushing the cars limits and keeping the throttle floored.





Homemade splitter with 5/16" plywood core and 2-ply carbon. Strong enough to stand on.
Homemade rear wing struts with APR GTC-200.

 

have you replaced the rear trailing arm bushings? A Lot of civici and integra racers have said the spherical bushing will calm down the car under braking

 

PM Kiwi and crack the whip :p

 

Even if not spherical, fresh rubber RTA bushings are a tremendous improvement in stability over old, cracked ones.

 

The entire front of the car is just like a big wing. Dont look at it as just the front lower part of the bumper where the splitter sits. But look at the entire car as a big wing.


Flow needs to go IN and OUT. These cars dont channel enough air from the pig nose facia to draw air from flowing by, so it needs to go threw By not channeling the air coming out of the radiator, you start creating a huge pressure zone in front of the radiator. Slowing down flow.
This is the reason why high end sports cars like the GT-40 has the vents on the front of the car. So that air can flow into the radiators, and out. The flow of the air coming out should be channeled properly as well, given that the air coming out of the hood area is at the proper velocity and angle. However this air can then be sent to flow over the top of the car properly and used to create even more down force from the pressure difference. (this is a very lengthy subject of its own, i would say that if you are interested you can find some old CAD and CDF diagrams floating around online explaining this)

No one said that building race cars is easy. The difference between a good car and a great car is the time, though, and money that goes into the proper design ( the Bugadi is 1.5mil if not more, but it also hits over 250mph).
This is why spending time resercing air flow, using computers to air in flow characteristics, and doing test and tune track days are beneficial to increasing cars performance. Every year a month before LeMans comes to Utah. The Spider team comes for 4 days and rents out the entire track for testing (not cheap), but their record in Utah has shown the time they spend testing is paying of in wins.

Reason is that Image was taken off a site, I didnt think that my MSPaint skills are up to par with my thinking to translate it into a accurate image.

But as again, racing is never cheap.


And thats the real world. Testing is as important as design. However testing should follow the design, and not design follow testing.
Design, test, log info, analyze, redesign if needed

Thats my plan right there for the majority of the 2010 Season. try new ideas that have never been applied to the honda platform. See if the ideas work, if not back to the drawing boards...

 

What aabout diffusers? In all the eg's posted I don't think any of them are running diffusers. Can I see some under the car pics?? And is anybody running the beat-rush underpanel? And how far under your car does your splitters go? I'm in the final stages of getting my HPDE hatch running and aero is one of the last things me and my buddy are lookin at, just tryna get some knowledge.
-tj

 

the whole car is a wing?? then why add aero??

 

A car is a cambered body like a wing, not an inverted wing. As a result, a car body will always generate lift unless some underbody aero is added to reverse some of this lift. Some cars, such as the Ferrari 355, 360, 430, ect. actually generate some net downforce due to airflow management under the car in addition to a reduced "camber" shaped body. And even if the car were an inverted wing shape, we would want more downforce than the body could create on its own and thus we would add aero appendages such as wings, splitters, canards, ect. to it.

 

At AutoClub Speedway,during a Redline Time Attack, I tested with and without a front airdam/splitter and rear wing. (I can post if desired) Some photos my pop took show my car having a tucking tire in front with my splitter and airdam,while later it also showed a gap between the fender and tire without the airdam and splitter,basically exhibiting lift at 130mph.No changes but the aero.
I also learned the aero package I am running has very minimal drag,as my laptimes were actually 1 second slower without the aero.I also was very uncomfortable at 130mph in the banking with no aero,the car felt like it was "on top" of the track and not "in" the track.

I agree with some good hood venting as well,just like a fart,releasing some pressure anyway you can will help.

 

If you are putting a car together and have never been on track before, don't worry about any of this. You're going to have so much more to worry about than good aero for the next few years.

 

That absolutely deserves to be quoted, LOL!

 

EVERYTHING about a spliter takes forever...

 

One big thing to point out.

With AeroDynamics when with increase of Down Force, increase of drag will occur. The "ideal" aero will create no drag, but a bunch of downforce. But as anything else thats imposable. As the force that creates the downforce splits into a downforce and a drag vector. Optimal if you can increase the downforce vector and decrease the drag vector, the more efficient your aero is.