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Discussion Starter #1
So, in the latter part of the V8 thread, we have started discussing the aerodynamics of the S-chassis.

Having followed the radiator test conducted by fellow 240 owners/enthusiasts on FA, it was proven that running the upper radiator panel and some sort of underpanel to direct air through the FMIC and into the radiator (instead of below or above the radiator) proved to work very well in lowering water temp. Makes sense.

From that alone, it should be evident that proper ducting of air can aid in the car's performance.

It is also evident that aerodynamics on any car can improve its performance, whether it be cooling or reducing drag/increasing downforce.

I started this thread because I am planning on creating an undertray that will work both as a lower radiator panel and a sort of a front diffuser. It will start from underneath the FMIC core, and extend to the engine crossmember.

However, from the articles linked to in the V8 thread suggests, there are many shapes/forms/angles/etc. to consider when dealing with aerodynamics, as anything, however minute, can cause a huge difference in the outcome.

I do not own one of those pressure gauges, so if someone on here has one, I wonder if you guys might want to be a guinea pig? haha

Basically, let's all enjoy a discussion of ideas for an undertray that would help in cooling and create downforce on the front of our cars.
 

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moe.ron
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597 Posts
Wouldn't any thing to decrease drag on the under carage increase down fores, because the air could escape faster and spend less time under the car??


well for the b13 se-r, I would say that the 240sx lip should aid in aerodynamics, and directing air in to the radiator. Along with some sheet metal panels on top and bottom,that should help keep things cool as well. plus the 240 lip is sexy. any opinions?

P.S. It will be cool when you pop the hood and explain the panels to a ricer :tongue:
P.S.S. I'm going to finish my panels and post them up....
 

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Check out Voltex's front diffuser for the EVO to get some ideas:
 

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I'm probably going to have a shop build me a front diffuser, side plates, and a rear diffuser, because I want real downforce on my car. Custom designing the stuff will be expensive, but cheaper than having parts shipped from Japan, or rigging up some other product to work.

Hopefully you get the front diffuser done before I have to do that, it would probably save me some cost. Also, don't forget to add some sort of support brace for it, because these things create enough force to suck the bumper off if it's weakly supported [check out all the support bolts on that Evo!]. Is this going to be a splitter/diffuser combo?
 

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Discussion Starter #6
I can see 1 problem with the Voltex's undertray: its usage of fins will compromise ground clearance.

I'm going to try to get my hands on some software for designing this undertray, amongst other things...

Hopefully I will have something fruitful soon.

I plan on putting my Z32 front brakes on tomorrow, so I might actually go under the car and just start cutting out a cardboard and test it out.
 

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Actually it's still flat if you look at it, notice the end plates as well- restricting side air being sucked into the low pressure area. Fins help increase the effect of the undertray, directing the air straight and increasing velocity, as well as not allowing it into the engine bay. Voltex actually wind-tunnel tests all of their parts.
 

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Discussion Starter #8
It is really hard to tell if it's flat or not. If the fins are flat, then that means the plate is pointing upward at the end, which may work for the Evo, but I don't see it working out for the S-chassis.

Problem is, our sway bar comes down in front of the stock oil pan, and with an aftermarket oversized oil pan, like the Greddy or ARC, some reported that even their sway bar will no longer fit due to the oil pan hitting it. Well, if that's the case, the front diffuser undertray cannot have an upward bend as it will direct air into the oil pan and such, which sort of defeats the purpose of directing air underneath the car and picking up speed.

While it's a good idea to draw from, some of the elements of that tray just cannot be incorporated into the S-chassis's design.

I am going out there in a bit, perhaps I will try to take a few pictures to help me design this thing.
 

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1995 240SX
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Ok well I have been into 240's for a couple of years now and here is my input.

A front defuser would look killer.

If you spend the time and money to fab up this thing I really would not use it on the street because of pot holes and such.

I may be wrong (please correct me if I am) but the fins look like they have no purpose unless there directing air right or left. Its hard to tell just looking at the one picture. And if they bend some how, well you get the picture.

I can't see why a defuser wouldnt work on a 95 and up 240 we have a scrape panel that covers all our suspension pieces and that is pretty flat and smooth. Not sure about you s13 guys though.

And if im not mistaken Top Secrets s15 uses a front defuser mabe that disign could help
 
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