Give us the truth, Paul. We can handle the truth!

Show us the light and give us a spot light and not a flashlight.

I know you don't have time to, but showing us colorful pics, graphs and schematics oh I love schematics (jk on the schematics) would be more beneficial

Here is some reading to look at, pay attention to paragraph 3, keeping air out from underneath, para. 4 and para 5 mentions the air dams purpose and F1 and indy car design add ons. The little side bar window on page 3 talks about the side skirts on a stock car which are riveted on and made from ABS to keep air from rolling under the car sides and creating lift.
My idea has always been to keep the air out from underneath my car not invite it under unless I'm willing to smooth the whole underside and add a rear difusser to help get the air out from under the car. Adding a upward sloping splitter in my opinion is letting more air under the car without an effiecent way of getting it out on our undersides unless you are willing to smooth the underside and add a well designed difusser with an upward angle of no more then 9* seems to be the max number most reading has said to not exceed or you well stall the air in the difusser. I have seen the spliter on the nascar cars and it is wider then the front bumper as it should be but it is not very deep back under the car, it sole purpose is to trap air on top to create downforce not increase the flow of air underneath the car. That is why I run 949's air dam up front and it also has spats that deflects the air up over the car side and tires which helps keep it from curling underneath along with the side wings I added over the winter.
I am no aero engineer but I have done alot of reading and been racing for 50 years off and on and sure don't know everything.HowStuffWorks "Stock Car Lift "

Read paragraph 4 in this article. HowStuffWorks "NASCAR Racing Physics 101". If I was to build a splitter I would use the nose like crusher uses and build the splitter to extend out forward as much as I wanted for downforce and that could change with which track I was going to run but I would not run it back under much as to speed the air flow under the car with a large surface and running it into a stock undercarriage. The main reason I don't run a slitter is I like to do off track excursions and having to pick up 949's air dam in 3 pieces and glassing back together is enough work for me. LOL!. Again just my 2 cents worth.

Here is a 2011 cot road course splitter and a used one for a porsche, check out the price used, and we think we spend money for something that gets tore up easily. http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40

muddy waters
 

While air is fairly predictable, I think it muddies the waters to talk about race cars with rules, and cars that are free of regulations. NASCAR and F1 operate under the strictest of rules, and if they were free from them you'd see their aero packages change drastically. So the "why" in racing is most often rules-based.

If you chuck the rule book you may end up with a bunch of Delta wing shaped cars with suction fans sticking out the ass end, active aero, and all sorts of other nonsense. :)

I was answering a question about splitter orientation. The rules don't change what works and what doesn't. I agree that if there were no rules aero would be over the top, but the design still has to work together.

John, according to my copy of Competition Car Aerodynamics, for a car with a quote unquote stock, "dirty" undercarriage (ie, no flat floor here - a nascar type sedan is the particular model used, but should apply equally well to our miatas) the effect of a front splitter is drastically improved when it is coupled with a front diffuser compared to a front airdam with a splitter sticking out the front and no aero behind the airdam.

When I create my front splitter, it will include a diffuser section running back to where the stock undertray mounts now.

https://www.miataturbo.net/attachmen...h_diffuser-jpg

My post wasn't in response to yours. It's just that discussions about aero solutions get muddied when racing rules are injected.

I hate aerodynamic racing rules. they are garbage. Remove the rules that limit aerodynamic advancement.

And watch any form of cost containment go out the window. The geek in me agrees with you - turn the engineers loose! see what they come up with! But in reality, what happens is non-competitive series where the best-funded team wins. Unfortunately in professional motorsports you must explicitly state what is and what is not allowed, and put some form of testing time constraints on the teams involved to control costs, otherwise the best funded teams will continually dominate and the back marker teams will continually be just that.

There's still plenty of work for the engineers, but the gains they are chasing are much smaller.

Reality is once they make something other teams will figure it out and copy it.

It occurs to me, for those of us chasing aero advantages and not bound by any form of competitive rules, that examining what is prohibited in these series could be advantageous.

I don't know that anyone on this forum is well funded enough to create a sucker miata. But limitations on diffuser depths and areas - side skirts - wing widths, chords, etc - any form of passive aero limitations are worth exploring. If it was limited, it must be for a reason, right?

But there will still be uncompetitive series while this is happening. Witness the active suspension on the Williams FW14 (an Adrian Newey car, btw). Mansell dominated the 92 season. At the British Grand Prix, he had pole by over 2 seconds (!!), second was his teammate Patrese, who was a whole second in front of Senna in third. That is not interesting racing when the car is obviously dominant compared to the field. Anybody qualifying 3 seconds ahead of Senna had to have a superior car.

And copying aero components blind, without understanding how what they did ties specifically into the rest of their car, doesn't always work out so well. Witness the number of teams that were unable to get the exhaust-blown diffuser to work for them.

If i wasnt living in an apartment building i'd be making a sucker miata.

I got won a competition that gives me engineering services from a company named Creaform. They not only make their own scanning machines, but offer FEA and CFD engineering. I'm really looking forward to them running some CFD on the bodywork, including the diffuser, splitter, and even air flow through the engine bay.

This stuff is as much art as science, as there are so many parameters that it takes someone with some talent and experience to accurately set up the tests, and then decipher the output.

Its not always that complicated guys, though more often then not it is.

I always thought that splitters work by exploiting the high pressure area where air hits the airdam/bumper. Provide a horizontal surface for that pressure to work on and you get lift or downforce. In the example pictured there is a horizontal surface both above and below the airdam, so that entire section will produce zero nett downforce. The added area is of no use at all.

No.

Hope that brilliant post didn't wear you out.

You're wrong. Totally and fundamentally wrong. Read this thread, look at the pretty pictures, and try to understand the words.

On this forum, if you post with authority as an expert on a subject, about which you actually know very little, you will get hammered.