Full Flat-Bottom Undertray EVO
Jun 15, 2008, 03:39 AM
#1
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Full Flat-Bottom Undertray EVO
So I'm working on some aero parts, and have my car setup with sensors to measure downforce etc. Evo's and pretty much every street car actually create LIFT, not down force at speed. Even wings and splitters on EVO's just help minimize lift, not create true downforce. Here's a thread talking about what I'm working on https://www.evolutionm.net/forums/sh...d.php?t=346323
I realized that the only way to really get past lift and into down force would be to clean up the underside of the car and make it as flat as possible, so here's what I've got so far
...
- Extended the APR splitter back to the chassis braces. Used aluminum sheet. I welded supports and captive nuts unto the chassis braces so it just bolts up.
- Full length plastic side skirts that stick out roughly 2 inches and come in under the car to the boxed frame.
- Center section, aluminum sheet slightly bent to create clearance for exhaust.
The car is now TOTALLY smooth to the rear axle/gas tank area. I just need to build a rear diffuser now.
Here are some pics.
I realized that the only way to really get past lift and into down force would be to clean up the underside of the car and make it as flat as possible, so here's what I've got so far
...- Extended the APR splitter back to the chassis braces. Used aluminum sheet. I welded supports and captive nuts unto the chassis braces so it just bolts up.
- Full length plastic side skirts that stick out roughly 2 inches and come in under the car to the boxed frame.
- Center section, aluminum sheet slightly bent to create clearance for exhaust.
The car is now TOTALLY smooth to the rear axle/gas tank area. I just need to build a rear diffuser now.
Here are some pics.
Last edited by jid2; Nov 21, 2008 at 01:20 PM.
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Jun 15, 2008, 10:47 AM
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Heat is on my mind as well, that's why the center section is aluminum. It's impossible to totally seal off the area between the undertray and the chassis, so there will still be airflow past the exhaust. If it is a problem I'll create scope to let more air in.
I don't have the money to go knock on Boeing's door and get some wind tunnel time, although it would be sweet. I have some test setups which can rough out lift/downforce and drag. I have some data from before the undertray, I just need to go out and get some more now. I just need a little time, probably in a few weeks.
The rear diffuser I'm planning will be for the USDM 8 bumper. It will require cutting the rear bumper, the lower lip of the bumper needs to cut away to create the proper shape for a real diffuser.
I don't have the money to go knock on Boeing's door and get some wind tunnel time, although it would be sweet. I have some test setups which can rough out lift/downforce and drag. I have some data from before the undertray, I just need to go out and get some more now. I just need a little time, probably in a few weeks.
The rear diffuser I'm planning will be for the USDM 8 bumper. It will require cutting the rear bumper, the lower lip of the bumper needs to cut away to create the proper shape for a real diffuser.
Jun 15, 2008, 11:28 AM
#14
This is exactly what I've been looking for the evo to be made. Putting on after market exhaust manifold on my friends 2006 330i I noticed that BMW's are pretty covered up underneath. No wonder why they hand pretty good on high speeds.
What about the factory jack points, are you going to leave any open areas for those? Its hard to tell from the pictures if you completely covered those up.
Also besides aluminum have you considered using high impact/temp plastic?
Excellent work for your efforts!
What about the factory jack points, are you going to leave any open areas for those? Its hard to tell from the pictures if you completely covered those up.
Also besides aluminum have you considered using high impact/temp plastic?
Excellent work for your efforts!
Last edited by BluEVOIX; Jun 15, 2008 at 11:31 AM.
