Custom flat underbody

[Bergycheese348]

Hey everyone.
Anybody have experience with a full flat underbody with these cars that can help with some insight? I currently have a front splitter and Verus diffuser (needs to be fixed), and will be throwing on my TRD skirts in a few months. I know cooling for the dif will pretty much be required (lets just say with a NACA duct or two), but is there anything else to consider? Would it work to have the panels go down to the level the side skirts are at or should I leave them at the height of the splitter and diffuser?

I am trying to not only help the car lose drag but to optimize the diffuser (help with downforce) as well. The car is my DD but it will start seeing a lot more track days and autocrosses this year, so the little things will add up overtime. Thanks!

[Bergycheese348]

Also as of now I cannot just use the Verus suspension covers because my TRD braces are in the way, so rather than cutting up perfectly good covers might as well integrate it all together.

[NoHaveMSG]

Haven't seen too much on flat bottom. It has the potential to help a lot but a lot of TT orgs it is only allowed in upper classes. I haven't seen any track day guys go through the hassle of running it.

[Bergycheese348]

Originally Posted by NoHaveMSG

Haven't seen too much on flat bottom. It has the potential to help a lot but a lot of TT orgs it is only allowed in upper classes. I haven't seen any track day guys go through the hassle of running it.

If they cannot see it, they will not know about it

But i am not so worried on classing, as with how many TRD parts I already have on the car as well as other stuff I would classify pretty high (especially after my supercharger). I know people like Verus have done tests with flat underbodys on a NA Miata with varying ride heights and aero and they all helped a lot, but no real advice/examples on how to build one. I am still studying in college and have not taken an aerodynamics course yet (planning on joining the FSAE aero team), but hopefully in a year or two I will have the knowledge resources to conduct my own tests.

[RedReplicant]

There is a FB group called Time Attack Builders that might have some of what you're looking for

https://www.facebook.com/groups/1134021793283517

[NoHaveMSG]

Originally Posted by Bergycheese348

If they cannot see it, they will not know about it

But i am not so worried on classing, as with how many TRD parts I already have on the car as well as other stuff I would classify pretty high (especially after my supercharger). I know people like Verus have done tests with flat underbodys on a NA Miata with varying ride heights and aero and they all helped a lot, but no real advice/examples on how to build one. I am still studying in college and have not taken an aerodynamics course yet (planning on joining the FSAE aero team), but hopefully in a year or two I will have the knowledge resources to conduct my own tests.

I know, but I don't roll that way. My car is already not class competitive, I do it for fun.


@jflogerzi has flat bottom on his car, maybe he will comment.
https://www.ft86club.com/forums/show...6&postcount=40

There is a good amount on flat floors online, but how do you quantify the numbers without testing? It's 100% beneficial, just can't say how much.

KYLE.ENGINEERS on YT has a bunch of video on car aerodynamics and the effects that are good introductions. He was an aerodynamicist for Mercedes F1 team for a few years so he knows his stuff.

[makinen]

You can see the holes in the rear bumper.
There are chances that hold heat inside the rear bumper space. So I made holes to escape heat out of that space.

The connector parts that hold the bumper skin to the chassis were toasted before making those holes.




This issue could be caused by my diffuser design which has little air escape except muffler tips.

[norcalpb]

Originally Posted by makinen

Attachment 219141

You can see the holes in the rear bumper.
There are chances that hold heat inside the rear bumper space. So I made holes to escape heat out of that space.

The connector parts that hold the bumper skin to the chassis were toasted before making those holes.
Attachment 219142
Attachment 219143
Attachment 219144

This issue could be caused by my diffuser design which has little air escape except muffler tips.

Is that NACA duct for the diff?

[makinen]

Originally Posted by norcalpb

Is that NACA duct for the diff?

Yes, it is 3D printed one for diff cooling.