I was going to post in show and shine but I figure I am looking for a functional splitter over a show splitter. I did some Google searching and not many people talk about the functional side of them. Just looking at photos it seems like the APR might be the best, but this is just based on the fact that is goes under the car more. I am assuming the more flat area under the car, even though it's minimal with the APR splitter, the better. Plus it seems like it can be adjusted with the two mounts in front. I am trying to stay under 400$. Any other suggestions for a functional splitter? Or maybe they are all functional? Of course I care about looks, but I like most of the splitters anyways so I figure I may as get a functional one and kill two birds with one stone.

Thanks, and if this has been answered maybe point me in the right direction because my search didn't show much about the APR, mostly places to buy them.

 

Here's one that DOES work. The splitter is APR with a sheet of Alumalite. EFI Logics fabricated a welded frame with brackets as the splitter is completely separate from the bumper . The splitter attaches with pins in the rear. The front sits on adjustable rods behind the bumper. The front rods you can see are really just decoration. With the rods behind the bumper we can adjust the splitter angle depending on the track. Riveted to the back of the splitter is an aluminum rail (gurney flap) that helps deflect the air back to the splitter. You can't see it but use a flap in front too, to seal the edge between the bumper and the splitter. It is a serious piece of aero.

 

You have to decide how you are going to use the splitter and how it will coordinate and work with other aero used on the car. Additionally, you need to think about why you need the downforce and what the intended affect will be on the performance of the tires, car, top speed, etc.. We use the big APR wing too, and adjust that constantly to manage downforce along with the splitter's impact, tweaking for different tracks and suspension changes.

With shorter tracks, for example, I want more downforce in the front, increase turn in, reduce pushing, faster rotation. Use a little more wing also, to manage rear grip and rotation. More wing is MUCH more grip but slower top speeds and I can't rotate the car as quickly (maybe we can add a couple of psi to the rear tires to loosen them up-that sort of thinking), so too much of a good thing is a problem. Shorter tracks, give up top speed for grip.

Long tracks or a long straight and we'll flatten the wing and splitter to get that top speed, but the car will have less rear grip and less braking. So you need to consider the different impacts and what the car is doing, and what you want it to do differently. Document everything, so you can look at the data later and see what happened. Splitters will make a real difference but you have to make sure it's a difference you want.

APR makes a very good product but it's the mounting that will make the difference. Also, these things tend to get beat up at the track, so be ready for that. The double of alumalite on the bottom of the APR stiffens things considerably and really helps protect the splitter with my periodic off road sideways excursions in the grass when I overshoot my braking point at turn 2 at Poconos North. (as an example...)

 

NICE!

Damn good thing I don't need to worry about any of this with Rally-X or Auto-X. In those disciplines a splitter is an expensive luxury that will get busted the first hard impact with a cone or worse rock.

That always got me about the difference between the Evo II and Evo III WRC machines. The III had the "advanced" aero which included a bit of a splitter/lip and it always ate it even on tarmac. Unless you got a show car or a dedicated track car that may not be the best thing to get if you daily your Evo.

 

Thanks. To be honest, splitters see some rough times on the track too, and I'm constantly clipping the underside on the rumbles, or as I mentioned, when I gaff and find some grass. We keep another one (sans hardware) ready to go in the trailer.

There is a bunch of testing that indicated that anything much below 100 mph or so and a wing has little added down force. It's not 0, but it's not too much, and a driver could add grip much more easily, with less downside of weight and resistance, by simply using a stickier tire or lowering their tire's air pressure a bit. The splitter helps a bit more at lower speeds, acting as a plow when the car is nose diving under hard braking. The splitter can add some pressure to the front tires, improving braking and turn in grip. To achieve that though you need to be at a fairly high rate of speed and on the brakes hard (get the nose down) to really benefit. And, here's the kicker, still going fast enough that, without the splitter, you would immediately break traction and slide.

So, I always smile a little when I see full splitters and wings on daily cars that don't see the track.

 

Just out of curiosity, I don't know much about aero parts, but instead of using the APR wing that you need to re adjust based on track use and such, then wouldn't it be beneficial to have the aeromotions wing that adjusts depending on the situation? Just a curious question, I guess it's slightly off topic.

 

yes of course, theoretically the active wing is the best of all worlds... downforce when you need it and drag reduction when you don't.

but since it starts at $6,000 for the active wing, it is a luxury few can afford and i'm sure it is prohibited for most classes of racing

 

Walk me through this, please. I have always thought of splitters as being a negative when it comes to pitch. When you brake, the splitter makes nose-dive worse. When you accelerate, the splitter makes nose-rise worse. Am I missing something? TIA

ps. am I allowed to say that your car is beautiful?

 

Thanks for the info. In regards to the nose diving being better for the down force I am assuming its because the lower the splitter is to the ground the better? The lower a car is to the ground the more down force right? I mean other things taken into consideration of course but that's why F1 cars basically drag the ground or close to it. As far as being needed for a daily driver or not, well we do a lot of things to our cars to give them that "race" look without actually racing them. For me it will be a combo of both. I mostly daily drive it and like the "race" look. But at the same time I would like to start track days soon so if I am going to get the part I figure I get one that performs as well.

Thanks again...

 

And in car wing adjustment is not permitted by our rules

 

Thank you VERY much.

I can't speak to nose rise but suspect, to some degree, that's correct. Though there is a small downward angle at standstill (I think 5 degrees - though I'm not positive as our notes are written as 0, +1, +2, -1, etc) so that, unless there is significant rise under power, there would be little wind picking up the nose. I don't notice that at all.

In regard to dive, yes, you are correct, the splitter does push down on the nose thereby increasing downforce and grip on the tires. Canards intend to do the same thing. If springs are too soft and you had much downforce then there could be negative suspension affects. Though I suspect it would be hard to isolate whether it is just a too soft suspension setting or a suspension setting in regard to impact from the front splitter. With an R compound slick I would probably look for some early body roll but the front outside tire to load up with grip and then give way quickly (exciting!), but would have to experiment a bit to confirm it was the splitter affect or just the spring rate.

 

Well, yes, as I understand it there are ground affects as the air moves under the car "sucking" it to the ground and so F1 cars are designed thus. This is slightly different, as I understand it from the splitter's intent as it has angle and shape impacting the car, such that as the car moves through the air the splitter angle deflects the wind applying down force. There are books on this stuff though and it gets complicated fast.

I think if you EVER, even once, take your car on the track, you are forever and fully justified in any mod you can conceive. Why? Because race car.

 

I think the lower the car the air molecules change being compressed into the smaller area creating a low pressure area. Allowing more down force. But I am no Adrian Newey!!

I wonder if you can buy a kit to enclose the bottom of a Evo to make it completely smooth? I understand that helps as well. I guess I could always do that with some plywood and nails...

 

Yes, you've got it right. You could make the bottom smooth but you need to think of a bunch of other stuff too, if you do, like weight, access, heat, the elements, and, if you are competing, the rules. Most sanctioning bodies limit underbody work to in front and behind (rear) axles, unless the car came with it.

There are other fish to fry, like corner exit speed and your line...

 

There are also downsides (as it were) to a perfectly flat bottom.