damir130

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).

jmann

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.

jmann

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?

Mobius

iTrader: (2)

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.

jmann

Understood. Thanks

ThePass

iTrader: (3)

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

jmann

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.

mr_hyde

iTrader: (4)

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.

1993ka24det

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?

1993ka24det

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

jmann

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.

cordycord

iTrader: (2)

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

Blackbird

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

Leafy

iTrader: (1)

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).

tpwalsh

Any pictures of how you mount your splitter?

Leafy

iTrader: (1)

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.

tpwalsh

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.

Leafy

iTrader: (1)

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.

tpwalsh

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.

Handy Man

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/