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Custom Fab Aluminum Diffuser

Old 01-28-08, 07:02 AM
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Custom Fab Aluminum Diffuser

S2000 owner gets a custom diffuser made out of aluminum. Looks good!!! Wish someone would make a nice one like this for the 7.













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Old 01-28-08, 07:09 AM
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i have my rear sub frame apart at the moment, i might take some measurements and see if i can cook something up for cheap.


that looks like 1/4" right?
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Old 01-28-08, 07:13 AM
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looks like 1mm thickness if you go by the pic w/ the riveter
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Old 01-28-08, 07:45 AM
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i think its 2mm, time to go steal the shops brake
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Old 01-28-08, 11:42 AM
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Without flattening the rest of the underbody and installing low side skirts this will have limited benefit. You want to create a low pressure area under the whole car, not just have a wing underneath.

My $0.02
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Old 01-28-08, 03:38 PM
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Originally Posted by TrentO View Post
Without flattening the rest of the underbody and installing low side skirts this will have limited benefit. You want to create a low pressure area under the whole car, not just have a wing underneath.

My $0.02
I'v been researching underbody aero for many yrs and that bit does help high speed stability. Lower +pressure is generated just by the mass of underbody without being perfectly flat and of course flat would be a greater benefit. This is a very complex topic but a buddy of mine used to work for Lockheed Martin and in his off time would calculate aerodynamic data for cars. Even the slightest changes make a difference. In this s2000 case its a dramatic change to air flow. I think the job is well done and you will def. feel a difference with that at high speed.
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Old 01-28-08, 08:17 PM
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if i m using that might as well just go with the RE-A one
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Old 01-28-08, 08:27 PM
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It would be hard to tell what real good the diffuser would do since they mounted that enormous wing at the same time. Lookes like a quality job though.

There was a Dodge Viper on ebay a few months ago that had a pretty cool diffuser that was cut into the bumper. Heres a pic.



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Old 01-28-08, 09:34 PM
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A diffuser allows the air traveling underneath the car a place to expand and decelerate back to road speed as well as providing wake infill. As the air enters towards the front of the car it accelerates and reduces pressure. There is a second suction peak at the transition of the flat bottom and diffuser. The diffuser then eases this "high velocity" air back to normal velocity and also helps fill in the area behind the race car making the whole underbody a more efficient downforce producing device by reducing drag and increasing downforce.

Understand that a true flat bottomed car (one without a diffuser) will produce downforce in and of itself when run in rake. Essentially the entire flat bottom becomes one large diffuser. It too has two suction peaks, one upon entrance, the second at the trailing edge of the flat undertray. A diffuser acts to enhance this underside suction, it acts like a pump, encouraging better flow under the car.

One thing to note is that the rear wing interacts with the diffuser "driving" it. The proximity of the low pressure side of the rear wing encourages better flow through for the underbody.

http://www.mulsannescorner.com/diffuser.htm
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Old 01-28-08, 09:36 PM
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Old 01-28-08, 09:48 PM
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http://www.fatcatmotorsports.com/iga...o_articles.zip

Download and read this, it'll help you understand and better design your own aero stuff.
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Old 01-28-08, 09:55 PM
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Originally Posted by Black91n/a View Post
http://www.fatcatmotorsports.com/iga...o_articles.zip

Download and read this, it'll help you understand and better design your own aero stuff.
Awesome free info!!! GUYS READ THIS!!! and if your still interested get books like this

BOOK 1

BOOK 2
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Old 01-30-08, 12:06 PM
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I keep looking at this diffuser on the S2k and have some questions.

First I would like to compliment the fabricator for a job well done, but it seems to me the front on the diffuser is actually acting like a splitter. Although I agree with what was said earlier "Even the slightest changes make a difference" a few things could have been done a little different and the benefits would have been much greater. It seems alot of air will be going above the aluminum and exiting the rear side openings of the diffuser which will probably create some down force but at the cost of ALOT of drag. the center of the diffuser looks good but the sides are what's probably going to negate any of the benefits of this diffuser. perhaps if they sealed the front of the diffuser allowing only enough room for the exhaust pipe or even raise the sides to look like the center so the whole thing looks like the diffuser posted earlier of the open wheel car.

Just my .02 worth, don't spend it all in one place
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Old 01-30-08, 02:17 PM
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I`ve got book 2 above, very very usefull. We even had the writer, Simon McBeath, come and analyse our race cars aerodynamics which was very interesting
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Old 01-30-08, 04:23 PM
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I have both the above books, and they are great. Katz work with the GTO RX-7 IMSA championship wining car was useful in this book.

I am concerned that the rough underside ahead of this part, will feed very dirty, turbulent air into the abrupt entrance of this part, which will reduce it's effectiveness.

Also, they mounted their big carbon fiber wing over the rear trunk lid, which reduces it's net downforce. As shown in the sideview of the prototype drawing above, the rear wing is more effective, and it boosts the diffuser, by mounting the rear wing aft of the rear trunk lid, not over the trunk lid.
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Old 01-30-08, 04:31 PM
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The problem with sealing it against the bottom of the car is that you need some cooling air for the exhaust pipe and the diff. Maybe with a diff cooler you could seal it up, but not otherwise.
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Old 01-31-08, 12:58 AM
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Well, I look at all this cool splitter fabrication and the custom body kit, etc. and figure that someone's spending the big bucks on a no-compromise track monster.

And then I see a car with a rag top (the aero equivalent of a parachute) and a rear wing that's sitting down in the dirty air behind it, and I am forced to conclude that this is a case of "show over go" in a bad way.

At this point I seriously wonder if any aero analysis was ever done for this car.

-b
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Old 02-02-08, 06:34 PM
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Im working on a front and rear aluminum diffuser as we speak....its still a long way from done. il post picks once im done...
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Old 02-02-08, 09:56 PM
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I'm personally not a fan of using aluminum for those sort of things, as it can very quickly get to looking like this. Plywood makes for excellent splitters, and is what SpeedSource uses, lexan or similiar plastics also work well.
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