Full Under Floor/Diffuser
Thread Starter
Joined: May 2004
Posts: 3,403
Likes: 6
From: DFW, TX
Full Under Floor/Diffuser
Hey guys...I haven't seen anything like this available and was wondering if any of you have tried it. I'm planning on building a full floor for the/my S2K using 1/4" plywood/fiberglass. Maybe eventually making something a little more durable.
So has anybody else done this? If I made something like this would anybody be interested.
So has anybody else done this? If I made something like this would anybody be interested.
Gotta keep the drivetrain cool. Post pics as you go!
Registered User
Joined: Sep 2004
Posts: 249
Likes: 0
From: Sunny Los Angeles
I went a little way down this road with my 911. I'm interested in seeing what you come up with, but here are my cautions:
1) Get a transmission temp gauge. You'll be surprised how hot things get when you eliminate airflow around it. Keep in mind that gear oil breaks down at a lower temp than engine oil. I guess the same would go for your differential (in my car, the two are the same).
2) Your springs are going to be an issue. An underbody treatment is tremendously height sensitive -- within 2-2.5 inches of the ground is often ideal, which is impractical on a production car (the picture above is an example of being much too high off the ground). If your kit does create some downforce, it's going to compress your suspension, changing the ride height, and likely 'stalling' out at some point -- at which point it will stop creating downforce, and the car will spring back up, and the process will start all over again. Side skirts will give your setup an actual chance of being effective, but they need to be very low -- and suspension travel will destroy them.
The same thing goes for when you decide to turn the car, only more so. The springs will compress on one side and you'll change all the angles under the car again, and downforce will disappear, with compression giving way to extension. And up you go -- just as you need that downforce the most. It's called porpoising.
There are definite advantages to smoothing out the underbelly of a production car (most of the production 'diffusers' you see are simply a blinged up way of doing this simple task). And I suppose with plywood and fiberglass you might be stumbling on a way to cheat on very low ballast if you're in a class that limits that sort of thing. Steel would be even 'cheatier.'
The nice thing about wings is that they keep working at different heights and different amounts of yaw. Meaningful underbody aero often requires big compromises on suspension compliance. 2000# and up springs are often used. Those kind of spring rates would be hell on the integrity of a production car's chassis.
Trending Topics
Former Moderator
Joined: Aug 2005
Posts: 13,078
Likes: 1
From: SoCal
Originally Posted by JackOlsen,Feb 23 2007, 12:30 PM
I went a little way down this road with my 911. I'm interested in seeing what you come up with, but here are my cautions:
1) Get a transmission temp gauge. You'll be surprised how hot things get when you eliminate airflow around it. Keep in mind that gear oil breaks down at a lower temp than engine oil. I guess the same would go for your differential (in my car, the two are the same).
2) Your springs are going to be an issue. An underbody treatment is tremendously height sensitive -- within 2-2.5 inches of the ground is often ideal, which is impractical on a production car (the picture above is an example of being much too high off the ground). If your kit does create some downforce, it's going to compress your suspension, changing the ride height, and likely 'stalling' out at some point -- at which point it will stop creating downforce, and the car will spring back up, and the process will start all over again. Side skirts will give your setup an actual chance of being effective, but they need to be very low -- and suspension travel will destroy them.
The same thing goes for when you decide to turn the car, only more so. The springs will compress on one side and you'll change all the angles under the car again, and downforce will disappear, with compression giving way to extension. And up you go -- just as you need that downforce the most. It's called porpoising.
There are definite advantages to smoothing out the underbelly of a production car (most of the production 'diffusers' you see are simply a blinged up way of doing this simple task). And I suppose with plywood and fiberglass you might be stumbling on a way to cheat on very low ballast if you're in a class that limits that sort of thing. Steel would be even 'cheatier.'
The nice thing about wings is that they keep working at different heights and different amounts of yaw. Meaningful underbody aero often requires big compromises on suspension compliance. 2000# and up springs are often used. Those kind of spring rates would be hell on the integrity of a production car's chassis.
Registered User
Joined: Sep 2005
Posts: 735
Likes: 0