flat bottom 240

[bowflex]

i'm thinking about building a flat bottom for my 240. i was wondering what people think some issues i may have. i would like to enclose it completely, but i feel that for that i'd have to have at least some vents underneath the engine compartment, probably with a vented hood and racing radiator and oil cooler. has anyone done this or heard of anyone doing it? I think i may have a front diffuser then have a flat bottom from the firewall back and then build a custom rear diffuser. any ideas or comments?

[GSXRJJordan]

You need to vent the air underneath the engine, since that's where the radiator vents to, and you need a vent for the diff.

Sasha from Canada campaigned a S14 in the Canadian GT class a couple years back, check the thread on ziptied: Sandra - Game Over. I love you sweetheart! (http://www.ziptied.com/forums/index.php?topic=7879.0)

He did a honeycomb bottom just like you're talkin about, have fun!

[HungryHank]

http://www.ziptied.com/Coppermine/albums/userpics/10252/05~2.jpg
http://www.ziptied.com/Coppermine/albums/userpics/10252/07~1.jpg

[nsn240]

I was going to post Sasha's car as well... Pretty big job and you definitely need to do your research..

Is this going on a track car or?

[Def]

Don't put NACA ducts as exit ducts(they are not efficient that way), and don't put ducts going to the diffuser ramp(it's a higher pressure area) if you do it.

I've been thinking more and more about doing this on my S13, but it is a lot of work and I don't see myself having the time in the near future. I've got quite a few ideas on it though, and will probably get a friend to take some pressure data around the car with some very "expensive" pressure transducer modules.

[ixfxi]

ive always wanted to do shit like this, and when i do it will be modelled after the aero ive seen under all of the exotic cars.

[bowflex]

i'm going to design it in a cad program and then model in with CFD software i have to see how the flow goes. that way i can improve the design and finally i have a lab technician who would build it for me out of 1/8" sheet metal (CF is just too hard to build plus rocks hitting it underneath would really mess it up). using the CAD software i can mark exactly where the bolts would go. but for now i have to wait for my engine rebuild to get back from the machine shop. hopefully will be soon though.

[INeedNewTires]

i'll be building mine within a month or 2, will post up a 'build' thread... full undertray, splitter, and diffuser.

[nsn240]

i'll be building mine within a month or 2, will post up a 'build' thread... full undertray, splitter, and diffuser.

Definitely gonna look for that

The Naca ducts on Sasha's car were to let in air to cool the diff and then the reversed ducts are for that air to flow back out - why wouldn't it be efficient? They're just acting as scoops to redirect that air back out

Bowflex - What program do you use to test airflow like that?

[ixfxi]

if anyone ever builds undertrays for the 240sx, i cannot say that they will sell millions of them.. but i can most definitely say that i am interested.


edit: undertray, and an aluminum hood for my s13! too things ive always hoped to get someday.

[bowflex]

it's a cad program that some technicians i work with would use. but the NACA ducts were designed as low drag inlets, it really shouldn't make that much of a difference for the relatively low speeds the ducts would be used, but it would be more work required on your part.

[bowflex]

does anyone have contact info for this Sasha person?

[cdlong]

they're designed to be low drag, but not in that direction. those are backwards and upside down from the way they're supposed to work.

[Phlip]

does anyone have contact info for this Sasha person?

SG Motorsport | Welcome (http://www.sg-motorsport.com/)

[email protected]

... 15 seconds, 2 clicks, no searching necessary.
Try harder, people.

[BustedS13]

i'm going to make a new skidplate out of a stop sign or something. the plastic one died a while back.

not really the same thing. but if i were going to the whole car..... i think a highway sign would have more than enough metal.

[RB240Mike]

sounds like a stupid idea and i giant waste of time

[soreballz]

^GTFO. You're probably the type of person who would say "Why buy SPL when I can get THE SAME THING from Godspeed for 1/3 of the price?"

Douche.

[RB240Mike]

mmm yea I have a Blitz LM.... so no, I'm not the type of person that will say that


It just seems like a giant waste of time and money, what would be the purpose of this and you cant even see it.

[SirSilvia]

mmm yea I have a Blitz LM.... so no, I'm not the type of person that will say that


It just seems like a giant waste of time and money, what would be the purpose of this and you cant even see it.
aerodynamics and oil pan/steering rack protection etc.
and by your logic you don't need an engine since like you said, you can't see it.
^GTFO. You're probably the type of person who would say "Why buy SPL when I can get THE SAME THING from Godspeed for 1/3 of the price?"

Douche.
I agree, GTFO

[Drifting-pedobear]

i detect some 2 fast 2 furious in this thread. if you cant see it, what good will it do?

who needs a steering colum theses days?

i really wanted to do this as well, im working on an alluminum one on my friends EG civic for time attack. one of the reasons the GTR is to amaizing is that the entire undercarage is flat, aerodynamics are so key in racing. not really for your DD, but on the track, they help tremendously.

[soreballz]

It just seems like a giant waste of time and money, what would be the purpose of this and you cant even see it.
Woooooooooowww... So you're one of THOSE people.

I was right the first time... Definitely a douche. I bet you would NEVER consider spraying your intercooler black, would you? "Well if I sprayed it black, people wouldn't be able to see the sweet silver with the blue Blitz logo! And if people can't see it, what's the point?"
Ugh.


BTW, I was talking about suspension when I made the reference about SPL and Godspeed. SPL doesn't make intercoolers.

[Ghost240]

this thread is full of "lol"

[Bigsyke]

The OEM skid plate is like $35.

I assume the tranny would need some sort of cooling?

I can see on most track cars a rear under valance would be enough, a full body skid plate would be too heavy and outweight its advantages, unless your dealing with carbonfiber.

Block the air from going underneath the car.

[BustedS13]

It just seems like a giant waste of time and money, what would be the purpose of this and you cant even see it.

i don't think you're going to fit in around here :/

[nismoskyz]

wow, i'm surprised to see others are thinking about this too.

i've been juggling the idea of this in my head for a while, although i have nowhere near the means of executing it.

[SirSilvia]

The OEM skid plate is like $35.

I assume the tranny would need some sort of cooling?

I can see on most track cars a rear under valance would be enough, a full body skid plate would be too heavy and outweight its advantages, unless your dealing with carbonfiber.

Block the air from going underneath the car.
btw if someone wants mine they can have it.
its not a 'skid plate' more or less a dust cover hahah.
As for the tranny, if you were really beating on it you can get a trans cooler. the stuff in those pics above do not look like metal, more like that plastic cardboard stuff. the stuff they make postal mail carriers out of.
http://blog.al.com/spotnews/2008/12/medium_1227post.jpg
http://www.preservationequipment.com/UserData/root/Products/Images/000311_0.jpg.thumb?w=283&h=283

[GSXRJJordan]

Sasha used aluminum honeycomb, not plastic.

[RB240Mike]

mm figured you meant VSPL. And SPL's are just ok IMO

So you are seriously gonna tell me a little piece of aluminum is going to keep your oil pan from getting cracked? Ummmm sureeeeee righttttt itll just get crushed into your oil pan and then your oil pan will crack, thats why I junked my Greddy oil pan because it sat to low and got cracked several times, went back to stock and its all good. So how often have you heard of stuff flying up and hitting your steering rack? Ummmm yea I havent. Here is my old hatch.... it was lower than im sure most all of your cars are and I never had a problem
http://c1.ac-images.myspacecdn.com/images02/32/l_5415f5db07c54d889deb615788901eec.jpg

and what would be the point of spray painting my front mount black? The car still has full aero, still has 50mm rear 1/4's, etc etc its not like its gonna draw attention away from the car. There would be no point so no why the fuck would i ruin a $800 intercooler.

I love how everyone gets attacked for their personal oppinions. Personally I am saying I see no functional point of it. Sure maybe this is a built track car for time trials or something, but I HIGHLY doubt it. O yes I am sorry I am a giant ricer because I have a uras BODY KIT on my car and I have SHINNY 18" volks and I spent $500 on a nardi wheel because I really thought it looked sweet, I thought about painting the wood though because it makes it look old. My next mod planned is some ubber cool pink street glow with some of those windshield washer light up things.

I mean seriously guys you are bashing me because I think its a bad idea?


Ooooo and BTW my intercooler has black writing on it not blue dipshit

[Nezahualcoyotl]

http://c1.ac-images.myspacecdn.com/images02/32/l_5415f5db07c54d889deb615788901eec.jpg

My next mod planned is some ubber cool pink street glow with some of those windshield washer light up things.

I mean seriously guys you are bashing me because I think its a bad idea?


Ooooo and BTW my intercooler has black writing on it not blue dipshit

hmmm pink street glow would go well with your car and those light ups are tight.........:ddog:
a flat bottom does wonders to a cars trackability. i would love to do this if i ever track my car...

[zenki.life]

wow dude you really are a douche just like everyone is saying. like you are just trying to pick a fight with everyone or something because you dont have a life maybe. negative attention better than no attention??? im sorry your mom didnt hug you enough as a little ugly child.
and just because you spend lots of money doesnt make you any less of a "ricer" youd just be a rice with lots of money, a ricer is a mindset.
remember this "everyone is hard behind their computer screens..."
mm figured you meant VSPL. And SPL's are just ok IMO

So you are seriously gonna tell me a little piece of aluminum is going to keep your oil pan from getting cracked? Ummmm sureeeeee righttttt itll just get crushed into your oil pan and then your oil pan will crack, thats why I junked my Greddy oil pan because it sat to low and got cracked several times, went back to stock and its all good. So how often have you heard of stuff flying up and hitting your steering rack? Ummmm yea I havent. Here is my old hatch.... it was lower than im sure most all of your cars are and I never had a problem

and what would be the point of spray painting my front mount black? The car still has full aero, still has 50mm rear 1/4's, etc etc its not like its gonna draw attention away from the car. There would be no point so no why the fuck would i ruin a $800 intercooler.

I love how everyone gets attacked for their personal oppinions. Personally I am saying I see no functional point of it. Sure maybe this is a built track car for time trials or something, but I HIGHLY doubt it. O yes I am sorry I am a giant ricer because I have a uras BODY KIT on my car and I have SHINNY 18" volks and I spent $500 on a nardi wheel because I really thought it looked sweet, I thought about painting the wood though because it makes it look old. My next mod planned is some ubber cool pink street glow with some of those windshield washer light up things.

I mean seriously guys you are bashing me because I think its a bad idea?


Ooooo and BTW my intercooler has black writing on it not blue dipshit

[n_my_coupe]

i have nothing to say

[SirSilvia]

Saying its stupid and a giant waste of time is determined it's purpose and the person wanting to do it.

And saying it's a giant waste of money, for not being able to see it?
doing a flat bottom setup might cost $150 plus about a handful of hardware. It's easy to get thin sheets of aluminum (not hard to find if you know where to look) or what ever the hell you want.

Again, like I said before, by your logic, an engine would be a giant waste of time. So would a performance fuel pump, and LSD, and if you tint the windows enough. The car wouldn't need your ass sitting behind the wheel.
THAT would actually be the quickest and easiest weight reduction mod right there, you could get rid of about 180+ lbs of unnecessary weight right there.
Should do a reduction to the forum's username database and remove you. Could add about 1-2HP to every new post after that.






Ooooo and BTW black or blue, you're still a douchebag.

[Def]

Definitely gonna look for that

The Naca ducts on Sasha's car were to let in air to cool the diff and then the reversed ducts are for that air to flow back out - why wouldn't it be efficient? They're just acting as scoops to redirect that air back out

Bowflex - What program do you use to test airflow like that?

NACA ducts are actually known as "submerged inlets" - they are NOT efficient at all when used as an exit. He's also dumping to a HIGHER pressure area than the inlets, as a diffuser's goal is to gradually get the lower underbody pressure to the higher freestream pressure.

[RB240Mike]

Lolzzzzzz haha you guys make no sense, now I know why I stick to lurking. I should figure out my password to my old screenname then I'd be all ubber cool with my OG join date, but then you guys wouldnt be like this so thatd be no fun.

I mean seriously WTF is you guys problem because I said it seemed like a stupid waste of time its like I stabbed your mother. Who cares, just like everyone says, its your car, DO WHAT YOU WANT, and yes, it would no be expesive, I could actually do it for free if I wanted, I have a like 100ft roll of 026 guage aluminum sitting around, but it seems to be a waste of time to me and would get fucked up pretty quickly. Apparently you havent done much fabrication if you are saying it wouldnt take long at all to make, to do it right it would take quite a while of measuring, cutting, bending, etc, things always take far longer than you think they would. Just like that clutch job you thought would take 2 hours and ended up being 6. IMO its always better to consider things being a bad idea and being a good idea, its stupid to jump into something head first then wish you hadnt wasted your time later. The fact of the matter is Im sure I've probably built more S-chassis than you have and have tried, or thought about doing just about everything, including this, then after weighing the pros and cons figured it would not be worth it. I'm not the "e-thug" here, you guys are. Instead of attacking my post because I really do think it is stupid and a waste of time, you coulda said you didnt think it was. But ehhhh to each their own, at any rate chances are I doubt the OP will ever even attempt this.

[xs240]

Actually Sasha is not the only one who's done this. There's plenty guys who have with even faster cars, just they are unheard of.

Check out on nissan road racing a guy from saudi Abdul is his username. His project thread is called "S14 road race car" He just recently raced his car against a 400,000USD 911 GT3 race car. His car has an LS7 v8

[Persona]

You guys are going too far with this IMHO, someone just stated their opinion which was different yes, but no reason to let it get this far. Lets just all take deep breathes now and turn on some mr.Rodgers!:rofl:

[murda-c]

no the guy said it was stupid because you can't see it. most people pick function over form.

[Persona]

no the guy said it was stupid because you can't see it. most people pick function over form.


This is true, but i have a feeling he isnt going to change his mind over some internet arguing. But i'll get back in the shadows now not to be seen again in this thread! :wavey:

[BustedS13]

no the guy said it was stupid because you can't see it. most people pick function over form.

painting your intercooler ruins it

$800 wasted

[kognition]

You can use that alumalite material, but it still has limitations.
Harman Motive made extensive use of it on their Subaru. I realize not alot of guys have access to better materials, but it does fill the void.
I am working on one for the S14, but i do not expect to sell many of them. Only because they are not cheap, and no shortcuts are being made. But you do need
to channel air in a separate tunnel to cool your trans and diff, if you make your own. Keep that in mind.

[Bigsyke]

The air being channeled would have to be drawn out somehow. You can test this by removing your shifter upper boot and opening your window. after about 20 mins of driving the air is pretty hot comming from that hole.

The idea of this is blocking air from getting under the car, and wicking away any air that does- as fast as possible.

However Im not really sure if most of us are going to see the benifits because honestly most user's trannys will run out of gearing before the undertray would produce results. Getting the car low, and running a front lip is almost all you need nowdays.

[RB240Mike]

no the guy said it was stupid because you can't see it. most people pick function over form.
Not what I meant, just meant I dont see its functional purpose since I am quite sure this is probably your typical $2k s13 build as 99.999999% of all s chassis builds are shit and since I dont see the functional purpose of it, and you cant see it.. whats the point.


painting your intercooler ruins it

$800 wasted

Would you pay as much for an intercooler that has some dumb fuck has spray painted black or would you pay more for it looking like new? If I was going to spray paint a front mount Id just get some ebay shit and do it. Use common sense.

[ThatGuy]

If you can't see the functional purpose of it, then you must not understand aerodynamics. As such, stop posting if you don't understand the conversation.

[chituntang]

Its just like putting a giant wing on your car. Does it aid aerodynamics? Yes. But when? Like when you are going over 120mph. Same thing for full underbody panel.

This is weighting pros and cons for a mod. But since we have no clue what the OP drives, what mods it has already, we should not determine if it is a waste of time, money, or what not.

My logic is wasting 12k on modding a 2k car is the same as wasting 12k on a 200k car. I did put enough on my car and mods that makes myself think that maybe I should just get a WRX. There is a point where modding your car becomes your personal ego. It is not economical because there are something better in the market already. And please do not tell me it gives me better feel, or driving fun, because I can bet you as fast and as easy as an EVO can be, you will still kill yourself when you drive it over the limit.

[Bigsyke]

^^^id rather drop 1/2 my stacks on my s14 than my lambo or ferrari

[ThatGuy]

Believe it or not, not everybody "settled" for a 240. There are real enthusiasts on here.

[Bigsyke]

I waited 5 years to get the s14. I started out with 2 civics, essentially maxed out the platform for what I was using it for. The S14 cought my eye as a better platform;

*Wider
*Much better engine platforms
*RWD with better xfer options
*The KA24de was a better platform than the B16 or D16y8
*Looks better than those Eg hatches that I hate so dearly
*true budget sports car

[zenki.life]

Believe it or not, not everybody "settled" for a 240. There are real enthusiasts on here.

haha A-FUCKING-MEN.

ZENKI 4 LIFE!......its even my screen name

[southerncross]

damn, i cant believe how many people here have no clue how much aero tuning affects a car. you can see benefits as low as 40mph when they are applied correctly. a good example would be that lexus ls430s have a dimpled full underpan to aid airflow at highway speeds and reduce drag, which enhances mpg. back in the early 90s honda played with the idea with the civic hatch vx, which had a small vortex generator at the rear of the car, which was also developed for mpg. just sealing all the cracks at the front of the vehicle and limiting air intake to the grille/radiator opening area can add considerable top speed to a car.

im not saying everyone should go out and tackle a project like this. mike, i see what you're saying in that you think its too much for a car that most people wont build to a level that necessitates this kind of fab work, but that doenst make it any less usefull to someone involved in time attack, which is what the S14 pictured is specifically for. i think its cool that regualar guys would want to attempt an engineering task like this. its hot rodding at is best.

and its something i'd like to try when i can devote my s13 solely to track use. until then, its just too damn low for a bellypan to be practical.

[jspeedm]

damn, i cant believe how many people here have no clue how much aero tuning affects a car. you can see benefits as low as 40mph when they are applied correctly. a good example would be that lexus ls430s have a dimpled full underpan to aid airflow at highway speeds and reduce drag, which enhances mpg. back in the early 90s honda played with the idea with the civic hatch vx, which had a small vortex generator at the rear of the car, which was also developed for mpg. just sealing all the cracks at the front of the vehicle and limiting air intake to the grille/radiator opening area can add considerable top speed to a car.

im not saying everyone should go out and tackle a project like this. mike, i see what you're saying in that you think its too much for a car that most people wont build to a level that necessitates this kind of fab work, but that doenst make it any less usefull to someone involved in time attack, which is what the S14 pictured is specifically for. i think its cool that regualar guys would want to attempt an engineering task like this. its hot rodding at is best.

and its something i'd like to try when i can devote my s13 solely to track use. until then, its just too damn low for a bellypan to be practical.

verry well put. just installing my body kit raised my highway mileage by 3-4mpg. now if i could just get city mpg up too.
to the op, if you think you can pull this off, then do it. the only down side i see to this is weight. good luck

[driftstyre]

You can use that alumalite material, but it still has limitations.
Harman Motive made extensive use of it on their Subaru. I realize not alot of guys have access to better materials, but it does fill the void.
I am working on one for the S14, but i do not expect to sell many of them. Only because they are not cheap, and no shortcuts are being made. But you do need
to channel air in a separate tunnel to cool your trans and diff, if you make your own. Keep that in mind.

The alumalite works very well as a step down from a composite piece. For the money (probably about 300-400 for the whole car) it is a good option. The whole floor was completed late last year on my nissan. I plan on a revised rear diffuser later this season but I adapted my old one to the floor.
http://www.dentsport.com/wp-content/gallery/240rs-maxi-aero/flat_bottom.jpg

http://www.dentsport.com/wp-content/gallery/240rs-maxi-aero/dscf6279.jpg

[Devil Man]

um wow^ that is quite the set up you have there

[BustedS13]

Would you pay as much for an intercooler that has some dumb fuck has spray painted black or would you pay more for it looking like new? If I was going to spray paint a front mount Id just get some ebay shit and do it. Use common sense.

....so when you build your car, you're thinking more about the resale than the functionality while you own it?
how much is it going to cost when you get a ref ticket?

[mrflip69]

Lucky he's in Flo-RIDA.

driftsyre: bringing in the hotness. too bad nobody can see all that nifty tubing when the body is on. "i just don't see the point"

...

hahahaha :)

Forgive me if I can't tell--is that your S13 Hatch up there? What engine are you running? Not worried about your diff overheating, having it sealed up completely like that?

300-400 for the whole car in alumalite isn't too bad. Is the material pretty stout?

[kognition]

Just as an fyi, the term is not "flat bottom", it is "undertray". :bow:

i'm thinking about building a flat bottom for my 240. i was wondering what people think some issues i may have. i would like to enclose it completely, but i feel that for that i'd have to have at least some vents underneath the engine compartment, probably with a vented hood and racing radiator and oil cooler. has anyone done this or heard of anyone doing it? I think i may have a front diffuser then have a flat bottom from the firewall back and then build a custom rear diffuser. any ideas or comments?

[xs240]

build an off the shelf option for 300-400 for s13s haha :)

[QuickSpoolSR]

The air being channeled would have to be drawn out somehow. You can test this by removing your shifter upper boot and opening your window. after about 20 mins of driving the air is pretty hot comming from that hole.

The idea of this is blocking air from getting under the car, and wicking away any air that does- as fast as possible.

couldnt you just put some spacers on the hood latches like everyone is doing these days?

[QuickSpoolSR]

Believe it or not, not everybody "settled" for a 240. There are real enthusiasts on here.

i am building a 240 from the ground up, because i love them, and how is making a viper killer for about 10 or 12k, less economical then getting a 25k scoobie and then having to mod that?

[soreballz]

couldnt you just put some spacers on the hood latches like everyone is doing these days?
That only works at idle and slow speeds. As the car gets moving, there is a low pressure zone at the base of the windshield, so if you have hood risers, the air will flow IN to the engine bay, not out.

[GSXRJJordan]

That only works at idle and slow speeds. As the car gets moving, there is a low pressure zone at the base of the windshield, so if you have hood risers, the air will flow IN to the engine bay, not out.

Correct. I know in my car, with an open front grill, there's quite a bit of air coming through the radiator, then down the sides of the engine - you need to get this air out of the engine bay either behind the front tires, or under the frame rails.

Just having cutouts and NACA ducts placed backwards would probably do he trick, but you'd have to actually put temp/air pressure probes in the engine bay and drive it to know.

[drftmark]

S14 the road racing car ! - Page 4 - Nissan Road Racing Forums (http://nissanroadracing.com/vbulletin/showthread.php?t=808&page=4)

this guy made a pretty nice diffuser.

and not to mention a badass car...

He started making the diffuser on page 4 and it goes on from there.

I recommend looking at the whole thread.

[PoorMans180SX]

NACA ducts are actually known as "submerged inlets" - they are NOT efficient at all when used as an exit. He's also dumping to a HIGHER pressure area than the inlets, as a diffuser's goal is to gradually get the lower underbody pressure to the higher freestream pressure.


Correct. I know in my car, with an open front grill, there's quite a bit of air coming through the radiator, then down the sides of the engine - you need to get this air out of the engine bay either behind the front tires, or under the frame rails.

Just having cutouts and NACA ducts placed backwards would probably do he trick, but you'd have to actually put temp/air pressure probes in the engine bay and drive it to know.


Said above, NACA ducts are not efficient backwards.

With that being said; Vent your hood directly behind the radiator. This is the lowest pressure zone on your hood, with your cowl being the HIGHEST.

Also, when you run a splitter, you can put a vent behind your engine bay if you're really worried about air escaping your engine bay. You really don't need it with a hood vent though. With that kind of underbody, you should have a lot of positive pressure against the intercooler/rad, which will push air through them and up and out the hood.

[Silverbullet]

Said above, NACA ducts are not efficient backwards.

With that being said; Vent your hood directly behind the radiator. This is the lowest pressure zone on your hood, with your cowl being the HIGHEST.



actually the highest profile on the hood has the lowest pressure/highest velocity. Refer to a venturi model where the area is reducing into the throat. The cowel has a high pressure zone due to separation from the edge of the hood.

On the topic of NACA ducts, make sure they have sharp edges for the most usage out of them. This will reduce the drag, and create vortexes to keep separation to a minimum. Many NACA ducts are improperly designed due to having round edges, even on competition cars.

//edit: ugg, just realized i CPRed a month old thread.

here, this is a good diagram to refer to. Just about all cars follow this general shape.

http://img20.imageshack.us/img20/6780/cupcarpressure.jpg (http://img20.imageshack.us/my.php?image=cupcarpressure.jpg)
http://img20.imageshack.us/img20/cupcarpressure.jpg/1/w821.png (http://g.imageshack.us/img20/cupcarpressure.jpg/1/)

[Def]

actually the highest profile on the hood has the lowest pressure/highest velocity. Refer to a venturi model where the area is reducing into the throat. The cowel has a high pressure zone due to separation from the edge of the hood.

On the topic of NACA ducts, make sure they have sharp edges for the most usage out of them. This will reduce the drag, and create vortexes to keep separation to a minimum. Many NACA ducts are improperly designed and are round, even on competition cars.

//edit: ugg, just realized i CPRed a month old thread.


http://img20.imageshack.us/my.php?image=cupcarpressure.jpg

The cowl area has the highest pressure of the hood surface due to the flow compressing against the windshield base/having to turn upwards. Has very little to do with separation.

[Silverbullet]

^
Compression? I recall there being recirculating air in that cowel area.

//edit: nvm, your right. I am looking at two different occurrences. The high pressure from the on coming air hitting the base of the windshield, and the recirculation from the highest point on the hood getting sucked in at the edge right before the windshield.

[JDMSTYLE]

having an undertray would be awesome as well as functional. thinking about making one to replace the cheap plastic oem one that on there.