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Discussion Starter #1
That goes below the bumper and makes the rear underside of the car more aerodynamic? I saw a pic a few months ago of it on a JDM car. The new STIs have it too. It may have had the word vortex in it.

Also, were do you get them.

EDIT: typo



Post Edited (Jan 7, 12:49pm)
 

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why do you want one? I don't think they look that great, and I pretty sure they don't have any effectiveness until you're nearing triple digits. . .so unless you're gonna be tracking it, it's not worth it, especially on an NA
 

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I like them, though not for the looks. I don't think they are $600-1000 cool though.

Maybe my reason for wanting one is silly and i'm not sure how much they help break up the vortices behind your car but they can help down force (at very high speed) and lower the drag coefficient. $600 is defiantly too much for me though.

Mega, if you can make one for cheap I would be interested though.
 

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If I can get the dimensions right, all it should take would be a single sheet of aluminum with 6 bends to make a flat underbelly with 2 vanes.

On the other hand, it may be a flat sheet with 2 v-shaped vanes riveted in place. If I do them, they will probably be powdercoated in a standard color, and they would probably be @25% of the cost just mentioned.

They would attach with Dzus fasteners.
 

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Diffusers, front or rear, can offer substantial improvements in your car's overall performance. It is not just for triple digits, any cornering around 60mph or higher will benefit from it. There is one issue most do not realize until it is too late because it is not advertised [for obvious reasons]. When you have a fully functional front diffuser it causes much higher engine bay temperatures, especially during racing. JGTC cars are very picky on how they design them to pull air out from the engine bay while keeping a relatively flat surface underneath.

Cheap ones are usually just a flat peice. While cost effective, heat build up [this pertains mostly to the front end obviously] will be an issue, ESPECIALLY on a car like the z32.

I've ridden before/after in a FD and the biggest difference was felt during changes in elevation, magnified further if the change in elevation involved a turn, like a large banking sweeper.
 

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Exactly...I have an aftermarket rear valence and it's bigger than the OEM. It surely produces more drag. If I make one for my car, it will just be a flat panel (no vanes) because vanes would protrude down too far. That is why the upward sweep of the OEM tail is conducive to vanes.
 

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Good discussion about an obscure topic - undercar airflow.

There is a comment in one of the Z32 design histories saying that Nissan Design considered adding a rear undertray similar to the good ones on the front, but they found that the car's shape did not benefit from one in wind tunnel testing.

Now, if the owner adds an aftermarket mod rear valance sitting far lower than stock, there might be a case of excess drag generation there. This is probably why many / most mod rear valances feature air venting. Not just for appearance, but to permit the trapped air to exit the car.
 
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