Rear Underbody Diffuser - Pics anyone?
Nov 25, 2003, 07:00 AM
#31
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I'm not talking about the GT-R, just the G35s rear underbody offering :
Aero Package ($550) includes a rear spoiler and underbody aerodynamic side fairings.
http://www.newcars.com/nctd.php?nctd_id=8&page=0
This si easy extra money for manufacturers, and consumers get so many benefits, improved stability, improved top speed, less wind noise, more fuel efficient.
Aero Package ($550) includes a rear spoiler and underbody aerodynamic side fairings.
http://www.newcars.com/nctd.php?nctd_id=8&page=0
This si easy extra money for manufacturers, and consumers get so many benefits, improved stability, improved top speed, less wind noise, more fuel efficient.
Nov 25, 2003, 02:00 PM
#32
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Originally posted by Mister2zx3
I'm not talking about the GT-R, just the G35s rear underbody offering
I'm not talking about the GT-R, just the G35s rear underbody offering
No.
When I don't quote a specific post but am replying to someone, logic would dictate it would be the post directly above mine.
He said "could be the new Skyline". Uh the G35 IS the new Skyline. But we all know he means "Skyline GT-R" and I was informing him that no, a G35 Sedan or Coupe with AWD is NOT the GT-R. The GT-R is not coming here for a couple years and it will be a supercar.
Last edited by JRock; Nov 25, 2003 at 02:02 PM.
Nov 25, 2003, 03:46 PM
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Then I guess you're having a conversation with yourself because if you didn't quote or address a specific post/poster you're either replying to the person directly above you (me) or you're TALKING TO YOURSELF in the middle of a forum! 
Way to fail at logic (or alternately, how to use a forum). Being a smartass and trying to argue with me will get you nowhere, because you'll lose every time.
Way to fail at logic (or alternately, how to use a forum). Being a smartass and trying to argue with me will get you nowhere, because you'll lose every time.
Last edited by JRock; Nov 25, 2003 at 04:44 PM.
Nov 26, 2003, 06:41 AM
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Originally posted by doraemonracer
remember reading an article for JGTC race cars
the whole rear diffuser really only comes into play assuming the underbody of the car is completely 'flat' .. the flat underside creates a channel for air to run toward the rear which in combination with rear diffuser and rear spoiler ... ... ... which is very uhmm impractical for street cars ...
the entire car had to be windtunneled over and over again to create the perfect combination to maximize downforce ..
soo slapping on some fins underneath your rear bumper isn't going to suck your car down onto the ground .... it's just for cosmetics if anything else ..
remember reading an article for JGTC race cars
the whole rear diffuser really only comes into play assuming the underbody of the car is completely 'flat' .. the flat underside creates a channel for air to run toward the rear which in combination with rear diffuser and rear spoiler ... ... ... which is very uhmm impractical for street cars ...
the entire car had to be windtunneled over and over again to create the perfect combination to maximize downforce ..
soo slapping on some fins underneath your rear bumper isn't going to suck your car down onto the ground .... it's just for cosmetics if anything else ..
When you say "flat" I assume you're saying it's free of any restrictions to airflow. How is that impractical as it would be cheap and easy to achieve.
Anyone notice yet how the new USDM Lotus Elise has a nice rear underbody diffuser STOCK? I can't wait for this car.
Nov 26, 2003, 07:37 AM
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I hadn't noticed the lotus underbody aero, but it is of no surprise, all manufacturers are finally starting to look on the underside to make the cars better in many areas. Mitsu talked about there wind tunnel work on the 8 in the front area, decreasing lift and reducing drag, I'd hope they would continue that work and get the entire underside reworked.
May 16, 2004, 05:42 PM
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May 17, 2004, 10:50 PM
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Originally Posted by doraemonracer
remember reading an article for JGTC race cars
the whole rear diffuser really only comes into play assuming the underbody of the car is completely 'flat' .. the flat underside creates a channel for air to run toward the rear which in combination with rear diffuser and rear spoiler ... ... ... which is very uhmm impractical for street cars ...
the entire car had to be windtunneled over and over again to create the perfect combination to maximize downforce ..
soo slapping on some fins underneath your rear bumper isn't going to suck your car down onto the ground .... it's just for cosmetics if anything else ..
the whole rear diffuser really only comes into play assuming the underbody of the car is completely 'flat' .. the flat underside creates a channel for air to run toward the rear which in combination with rear diffuser and rear spoiler ... ... ... which is very uhmm impractical for street cars ...
the entire car had to be windtunneled over and over again to create the perfect combination to maximize downforce ..
soo slapping on some fins underneath your rear bumper isn't going to suck your car down onto the ground .... it's just for cosmetics if anything else ..
According to Race Car Aerodynamics: designing for speed (by Joseph Katz) , underbody diffusers work with a flat body undertray to increase downforce under the rear of the car by creating venturis. To get an idea of the effect, an F355 Ferrari uses a flat undertray and an upward sloping rear diffuser to gain "about 170kg of downforce at 290km/hr."
The Evo can't get near 290km/hr, roughly 175mph, nevermind that the rest of the underside is not perfectly flat to help either. If true aerodynamic efficiency is the goal, it would take a huge amount of work.
Maybe the best way to get increased downforce in the back of the Evo is to use the Vortex generator strip like is on the MR, in conjunction with a gurney strip on the rear wing, which is available at RMR. Thats what I'm going to try, along with the front canards.
Just my .02, with a little help from Mr Katz. An awesome book, if you're into racing aerodynamics in a geek way!
