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Old 02-19-2013, 08:57 PM   #81
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I like the Kazespec mount kit for the same reason I like the FM COT uprights - it's a fair price that saves a person quite a lot of fabrication. Making your own stuff gives you the freedom to design it any way you can dream, but that can be a double-edged sword - many DIY designs are not very good. This design works, and not everyone has the knowledge/skills/tools/space/time to make their own.

Henry (Kazespec) was going to do solid angle mounts but it wasn't the most visually appealing package - I suggested heim joints and I'm glad he went that route. They add to the cost but the finished product is very nice.

-Ryan
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Old 03-03-2013, 11:56 PM   #82
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Quote:
Originally Posted by plucas View Post
Since this is about front splitters and air dams, I will leave the info I have gathered with miatas using cfd. This is a watered down version

1. Stock 1990-1997 Mazda Miata
2. Stock 1990-1997 Mazda Miata at a 4in Ride Height
3. Small Front Air Dam at 4in Ride Height
4. Small Air Dam with Splitter at 4 in Ride Height
5. Large Air Dam at 4in Ride Height
6. Large Air Dam with Splitter at 4in Ride Height

Note: The air dam and/or splitter is 2 inches off the ground in study 3-6


CFD Models


The solver used for these analysis is a steady state incompressible solver with a k-omega SST turbulence model.

Data


Cd = coefficient of drag
Cl = coefficient of lift
L/D = lift divided by drag / aerodynamic efficiency
Can anyone comment on why the lowered model(#2) has higher amount of drag than the stock model(#1). This seems counter intuitive.
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Old 03-04-2013, 12:02 AM   #83
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Quote:
Originally Posted by Redlined600 View Post
Can anyone comment on why the lowered model(#2) has higher amount of drag than the stock model(#1). This seems counter intuitive.
I did not go into much detail on the stock and lowered analysis because I didn't think people were very interested in that part. Basically when the car is lowered, the front bumper interaction with the rotating front tires increased the drag significantly. This interaction wasn't nearly as profound with the car at stock ride height. Maybe I will as some cut and or streamline plots to show this. With the air dams added, this changed the flow characteristics and decreased the drag by directing air in different locations.

Also drag should increase on a car with an undertray as the ride height decreases. This is the opposite of regular cars as lowering it decreases the amount of airflow under the car which will decrease drag. This is because the underside of the car is not smooth.

Hope that clears it up a little bit
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Old 03-04-2013, 02:22 AM   #84
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I dont get this part....

Quote:
Also drag should increase on a car with an undertray as the ride height decreases. This is the opposite of regular cars as lowering it decreases the amount of airflow under the car which will decrease drag. This is because the underside of the car is not smooth.
I have an air dam (no splitter) and just added an aluminium undertray from the bottom of the air dam to the front of the crossmember (same rear mounts as the OEM plastic one).

Are you saying I am better off without that tray....?

Not trying to be a dick, just interested to know and why/how....
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Old 03-04-2013, 05:10 AM   #85
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Look at it in extremes:

If you have chaotic, turbulent, uncontrolled mess under the car, you are better running it as low as possible to keep as much air out as possible.

If you have a glass smooth, engineered airfoil for an undertray you want the car up higher so the air can interact with the surface properly.

Generally, the 'truth' is somewhere in the middle since our splitters/undertrays aren't perfect entities. I'm glad to hear this concept from plucas though since my car is low enough and I'll be running version '6' this season.
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Old 03-04-2013, 07:21 AM   #86
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Quote:
Originally Posted by mx5-kiwi View Post
I dont get this part....



I have an air dam (no splitter) and just added an aluminium undertray from the bottom of the air dam to the front of the crossmember (same rear mounts as the OEM plastic one).

Are you saying I am better off without that tray....?

Not trying to be a dick, just interested to know and why/how....
No I am not saying that at all.

Basically if you have a full undertray:

As ride height decreases - usually drag will increase and so will downforce
As ride height increases - usually drag will decrease and so will downforce


Going from a car with no undertray to an undertray:

Drag will decrease and downforce will increase

When I say drag will increase, I am not talking about a lot. Undertray and diffusers are one the most efficient aerodynamic devices and can have L/D numbers of 300:1

I can get more into this tonight if it needs cleared up more.
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Old 03-04-2013, 07:24 AM   #87
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Quote:
Originally Posted by plucas View Post
As ride height decreases - usually drag will increase and so will downforce
As ride height increases - usually drag will decrease and so will downforce
My old Wrangler with 6" lift will disagree with you on that one.
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Old 03-04-2013, 11:24 AM   #88
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Quote:
Originally Posted by plucas View Post
Basically if you have a full undertray:

As ride height decreases - usually drag will increase and so will downforce
As ride height increases - usually drag will decrease and so will downforce
Quote:
Originally Posted by triple88a View Post
My old Wrangler with 6" lift will disagree with you on that one.
You have an undertray on your Jeep?
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Old 03-04-2013, 07:47 PM   #89
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Some more empirical evidence from Grand Am prototypes. Here are some photos I shot at the Rolex Series race this last weekend at Circuit of The Americas (CoTA). Their splitters are quite low as well. CoTA is a very smooth track so they can get away with low splitters.





Here is a photo of what happens when you jump a curb at the apex and launch your Grand Am prototype up in the air a foot or two off the track. When the car came back down it knocked the nose completely off the car. He pitted, his crew taped on a new nose, and they returned to the race, fighting for the lead near the end of the race. The tape (more like a big patch) they used was even color-matched to the blue paint on the car. I digress but the whole thing was pretty cool.


Skip to 1:10 in the video
Attached Thumbnails
Splitter Height-stadium-1.jpg   Splitter Height-stadium-5.jpg   Splitter Height-telmex%252520no-nose.jpg  
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Old 03-04-2013, 08:49 PM   #90
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Quote:
Originally Posted by mr_hyde View Post
You have an undertray on your Jeep?
Under armor that was up to about the transmission, the transmission has its own undertray that for protection, the only part that was exposed was the part behind that which was right above the axle.
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Old 03-18-2013, 12:10 AM   #91
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I was working on my splitter mounts today, but its definitely going to be to low to drive on the streets. The one I had before was good until I hit standing water and it decelerated the car from 35 mph to 5 and about slammed my friend's head in to the dash.







Attached Thumbnails
Splitter Height-20130317_185607_zpsd317c0ea.jpg   Splitter Height-20130317_185650_zps5dcca00a.jpg   Splitter Height-20130317_190654_zps9b97de71.jpg   Splitter Height-20130317_190812_zps33f9018d.jpg  

Last edited by 1993ka24det; 03-18-2013 at 01:18 PM.
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Old 03-18-2013, 02:38 AM   #92
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Planning to run some really stiff springs right?

Quote:
Originally Posted by 1993ka24det View Post
The one I had before was good until I hit standing water and it decelerated the car from 35 mph to 5 and slammed my friend's head in to the dash.
This is less a problem of the splitter's and more a problem of a lack of seatbelt...
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Old 03-18-2013, 04:34 AM   #93
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what is that bolted to?
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Old 03-18-2013, 10:14 AM   #94
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Quote:
Originally Posted by motormechanic View Post
what is that bolted to?
I haven't got to that portion yet but it will be mounted to a tube structure under the bumper cover

Right now it is bolted to factory support for the bumper cover and it holds my weight fine, but it needs more

ThePass---I'm getting a set of Xida's. How much do you run your car on the street? and how high is your splitter?

Last edited by 1993ka24det; 03-18-2013 at 10:50 AM.
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Old 03-18-2013, 11:28 AM   #95
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Seems like a good height to me. It should be the same height as the rest of your undertray, or slightly higher.
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Old 03-18-2013, 12:49 PM   #96
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ka-t: what happened to you getting v maxx? I remember you didn't want to pay that much for suspension?
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Old 03-18-2013, 01:17 PM   #97
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Quote:
Originally Posted by Dot3 View Post
ka-t: what happened to you getting v maxx? I remember you didn't want to pay that much for suspension?
Well I guess its because, you get what you pay for
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Old 05-15-2013, 03:35 PM   #98
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Does anyone have any educated guess as to how 3-4 would interact with a Street Prepared 10" spoiler? Or with the top down?
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Old 05-15-2013, 03:38 PM   #99
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Quote:
Originally Posted by Canyonfive View Post
Does anyone have any educated guess as to how 3-4 would interact with a Street Prepared 10" spoiler? Or with the top down?
How good is your SP spoiler? On a really good spoiler, 3 makes a bit too much downforce for the spoiler and 6 doesnt make enough. So 4 shouldnt come even close to making enough. I dont have any data on, not a good spoiler. But wemmons runs 4 on what looks like not a good spoiler so he'll have some data.
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Old 05-16-2013, 03:35 AM   #100
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Quote:
Originally Posted by Leafy View Post
How good is your SP spoiler? On a really good spoiler, 3 makes a bit too much downforce for the spoiler and 6 doesnt make enough. So 4 shouldnt come even close to making enough. I dont have any data on, not a good spoiler. But wemmons runs 4 on what looks like not a good spoiler so he'll have some data.



48 in wide 60 degree angle. 10in high (max height allowed)
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