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.

Please educate me and explain to me exactly where all these total and fundamental errors are. I looked at the pretty pictars and I understand them. Do you?

I'm ready to get hammered if I'm wrong, but to come up with actual arguments and logic seems to be beyond you. Oh the effort of typing!

PS, since when does starting a sentence with "I always thought that", count as "posting with authority"? I added it as a bonus for people to be able to post: you're a complete idiot... (got to that part no problem), and here's why (more difficult).

Mobius As stated above because of too many off track excursions I use the KISS method. I don't disagree with you, but we all have to weigh what is ideal and what is practical. I am able to remove my air dam for loading and unloading very easily. A splitter I agree has to sit higher because they are harder to remove and install for loading and unloading, and for that same reason I choose to run 949's air dam and it sits 2 1/4" off the ground. Just 2 Fridays ago at the Ridge going into turn 6, which is a big carousel to the left, I came up on a GT3 and for some reason he decided to hit the brakes in the middle of the corner and he spun. Well I was closing behind him fast and was going to go by on the inside but as I was getting the thought to start turning inside of him it was to late, so I had no choice but to hit my brakes or hit him and the R6's didn't like that much and a couple 360's later I was sitting out in the dirt with a 3 piece air dam. I removed 4* of rear wing to help balance the car without a frt airdam and picked up 4 mph down the straight.
One thing we all need to keep in mind is on our cars when we create more down force we are creating most of the time more drag and unless you are running big whp you can get to much pretty easy especially with a nat. asp. car, so the more whp the more exotic you can get I guess. There is no 100% right way but the design has to work fundamentally whatever way you choose.

Mobius I guess I'm a little confused. I too thought that the air hitting the air dam above the splitter caused a high pressure area at the air dam. I don't have that book you mention but I thought it would act like say at the base of the windshield not knowing anymore then I do. I know the main function of the splitter is to direct more air up and over the car creating high pressure and less under the car creating low pressure and a vacuum effect. Here is another read I found, very good read. Read the splitter part. Course maybe I am misunderstanding your answer to damir130. Aerodynamic Upgrades, devices for increasing downforce.
Also wouldn't you still have to have an efficient bottom with a rear diffuser to run a diffuser with a splitter to keep from slowing the air flow behind under the car?

No, you don't have to have a fancy flat floor to see benefits. That was the point of the cfd plot I posted. Even with a dirty undercarriage and no rear diffuser, the effectiveness of a front splitter is still enhanced by transitioning the airflow from the splitter to the underneath of the car smoothly with a diffuser. Airflow will still be increased by it, and the low pressure created by the splitter is allowed to act over a larger surface area.

The CFD plot I posted was done on a nascar-type sedan with no aero enhancements underneath (no flat floor, no rear diffuser, no fancy aero control arms) - so reasonably similar to our cars.

Understood. Thanks

jmann, sounds like some work put into designing a quickly removeable/replaceable bumper and/or splitter would be beneficial to you. I have the same "Production style" bumper as Crusher. The bumper is removeable in ~10 seconds, and the splitter is removeable in ~30 seconds despite still being as strong as can be (handles at least 450 lbs of people standing on the front edge)

-Ryan

Thanks for the thought, but my car is very well balanced as is and I really don't see any reason to change the front using 949's air dam. Might one day in the future though, can't never tell.

John can put on his spare air dam in a few minutes without going under the car. He just needs to watch the closing speed on poorly driven Porsches so he doesn't loop it in long sweepers. :party:

In one of the models that Paul designed makes approx 190 lbs @ 100 mph but I want to make more like 300 lbs. When I was talking with him, he was saying that the Miata wasn't the best in making downforce in factory form unlike alot of other cars. So what on other factory cars is more efficient? What on the hood, fenders and the "Crusher" type bumper could be changed for lower drag and more DF?

This is a bumper a guy named "Ben12a" on Time Attack Forums built from foam and fiberglass.

https://www.miataturbo.net/attachmen...ine=1369679581

https://www.miataturbo.net/attachmen...ine=1369679016

Now thats a splitter I could go with except for any off track excursions would HURT!! Very cool. I wonder why the big openings on each side of the grille though. He has what looks like brake cooling ducts down lower on each side of the grille opening. I bet one is engine oil cooler and the other is trans or some other cooler, I would think he should have some large fender vents to extract the air. I had a fiberglass company in FT Lauderdale years ago, doing work on boats and that is a REALLY nice job of making that nose.

posterity
 

So for posterity, was it Paul who made the first "Crusher" splitter design or 949?

Neither, E production cars have been running similar noses for many years now.

If you design your aero to come off quick it'll come off quick. Splitter, air dam, and wing on my car all come off before it goes on the trailer. I was on the trailer and strapped down within 20 minutes of being released from impound in jersey. And the wing takes longer than the splitter. In total its 6 dzus (air dam), 4 thumb screws, 4 quick pins (splitter), and 4 allen head bolts w/nuts (wing).

Any pictures of how you mount your splitter?

I cant find them. I already want to re-do it. I bolted my down mounts to the inside of the frame rails. After removing the fender liners I realized I should have mounted to the outside of the frame rails since its flatter and easier to access. I used Al square tube from mcmaster that is designed to slide in and out of each other so I can actually have 2 splitter heights. The clearence is tight so it is somewhat of a pain to get the splitter on initially, it takes 2 people and is something I want to work on. Once I finally break this one I'm going to switch the design to mounting on the outside of the frame rail. Also if I was going to road race with this splitter I would consider adding a hook mount in the rear so it could hook onto the sub frame by the steering rack. Right now it is only mounted in the middle and the front, but its stiff enough to get away with that.

Fair enough. I've been trying to come up with a way to remove the whole nose of the car for transportation, but haven't quite come up with a good design yet.

Just use 4 bolts under the hood for the bumper, and cut the point out where it bolts to the fender and replace it with a quick latch like thing. Something like these but smaller theres plenty of options. And if you have a splitter, mount it to the bumper solid, hook it to the sub frame, and use these with the set screws replaced with thumb screws to hold up the front of the splitter and have them bolt to the bumper beam or baby teeth mounts. You'll want one of those battery powered ratchets to make getting the 4 bolts under the hood off faster. But that should work out really well.

Note, if you don't make the splitter long enough to go all the way back to the sub frame and/or dont mount to it, and just use a bumper cover mount and a front mount even at auto-x speeds you'll make enough downforce with the splitter to visibly put stretch marks in the bumper cover.

That's the part that I'm trying to avoid. I also can't run the splitter behind the wheels. This project is pretty low on the list right now. Need a spoiler first, and a good running car before that. :)

Like Blackbird said, EP cars have been doing similar setups for a while... but since you asked, here is the original thread from when I did mine back in 2011, it was the first non-EP Miata with one that I know of: https://www.miataturbo.net/race-prep...ducting-60291/

MAD MAX meets Miata!!! I like! :)

I used 4 dzus fasteners along the top edge and then one on each corner with these brackets attached to the fender. Has held up that way for 2 seasons but it's just the bumper skin.

Pictures:
https://www.miataturbo.net/attachmen...ine=1369870851
https://www.miataturbo.net/attachmen...ine=1369870851

I will be working on the same idea, but a tube frame for the bumper supports. The radiator for the engine swap will be moved from the stock 8 deg angle to 30-35 deg angle. There will be a radiator duct exiting out through the hood. Here is a close pic to what I will be working on in a month.


AMS Evo X Hood Radiator Vent
https://www.miataturbo.net/attachmen...ine=1370134596

https://www.miataturbo.net/attachmen...ine=1370134596

http://i526.photobucket.com/albums/c...ps5bca97d3.jpg

Attachment 185389

Why is the hole not a gaping hole?

I think its because there is an engine in the way..lol

Its kinda making a wing shape with the top of the hood and the top portion of the Radi duct.

I talked to Paul (plucas) about it and he recommended a low resistance flow radiator

https://www.miataturbo.net/attachmen...ine=1370143040

https://www.miataturbo.net/attachmen...ine=1370143040

https://www.miataturbo.net/attachmen...ine=1370143040

I'm referring to the hole in the front in front of the intercooler.


https://www.miataturbo.net/attachmen...ine=1370134596

I think it was in the book Maximum Boost that talked about when making a duct to go to the radiator or intercooler has to be 20%-30% smaller than the surface area of the heat exchanger. I guess it is to draw the air in, instead of force it in with drag on the car.

triple post please delete

triple post please delete

Finally took this out,

Monster grip, very very stable.

Happy days.

Turbo setup held up good also.

In, passed scrutineering no hastles, drop the tyre pressures on the slicks, check, double check, triple check.

Out for qualifying, first lap out, first time down the straight the splitter failed.

I tested it to about 150kg jumping on it so I was amazed, when he came in a quick check showed that it generated so much downforce it tore chunks of steel out of the bodywork!

http://s24.postimg.org/nnalzjlyt/20130601_104609.jpg

Here is a piece I retrieved from the other side.

https://www.miataturbo.net/attachmen...ine=1370144644

Its held on with 6 bolts and only the front 2 had issues, so lesson learned, the splitter is way way more efficient than Id even hoped so it was remounted with a temporary but strong solution. So great news about the front aero design, also looks like the cooling issues the car has always had have been solved with these recent changes.

Here is the excel series and the pulsar series in together.

And a few pics from the field.
http://s24.postimg.org/52qz67px1/20130601_095653.jpg

https://www.miataturbo.net/attachmen...ine=1370144644

http://s24.postimg.org/ka6yqkhrp/20130601_121029.jpg



Dann

OK so a triple post but that is a good looking track Miata. I mounted my splitter to a steel structure that bolts to the factory bumper bulges (bumper bulges been removed)

Fuck me, can someone please fix the TP.

I didnt realise, I was having trouble with firefox, using chrome now, swore I never would.

Thankyou mate, this was remounted using the factory weld nuts you can see in the first photo.

Thanks
Dann

Also the hole has to be smaller than the surface area of a cooler because if the coollers frontal area is 50% metal, 50% air holes then it will only flow 50% of its area wont it.

Dann

Oh i see. Well you learn something everyday. I always thought you wanted more pressure in there.

No it doesnt need to be smaller but thats why it can be, My apologies.

Im fairly certain making it larger doesnt do anything because there isnt more pressure just a boundary layer.

Dann

Your thread was my inspiration to build mine. :party:

Nice work Dann.

:)

You are a LOT of my inspiration Dave.

Dann

Awesome :bigtu:

Regarding the heat exchanger intake area: The reason you want the intake area to be about 1/3 of the frontal area of the heat exchanger is due to bernulli's principle. The efficiency of a heat exchanger is affected by the pressure differential across it. Bernulli says that when velocity decreases pressure increases. So if we have a small opening with ducting that opens up behind it, the velocity will decrease as the cross sectional area of the ducting increases and it will create a higher pressure in front of the heat exchanger.

Regarding your torn out splitter mounting points: why not use those nice reinforced threaded holes just above the holes you used? Thats what I've used to support my similarly sized splitter for years without any problems.

Thats what I ended up doing..

i dunno..

I dunno.

Anyway lesson learned and thats the important part.

Dann