Spaniard

iTrader: (1)

Any opinions on whether this would help with downforce... or is it strictly a looks-enhancing mod...

For the advanced forum-er
If you think it would help with downforce/performance- please mention how much. - Technically, I can see it helping increase downforce maybe 5% over 60 MPH- but does that really mean anything??? All comments welcome.

http://www.paradox-systems.com/gallery.html

dawalkster

iTrader: (1)

it might help a bit but if you really want some downforce, i remember a post awhile back where a guy put a splitter on the front of his max. he said it dramatically helped, and that his car was much more stable on the interstate at high speeds. didnt look to bad either

Terran

iTrader: (6)

You were close. It will increase downforce exactly 4.7954932% at 60mph.

mansurxk

iTrader: (14)

downforce is neglible until you hit over 120 mph. and waht is that spoiler doing to produce downforce.....nothing, its flat theres no air resistance over that window spoiler. im not an advanced forum'er, but i took a million semesters of physics and engineering courses. on the same note, the spoilers on our cars dont do anything either because of the space between the trunk and the spoiler, all the air passes through the gaps instead of applying downward force on the top of the spoiler.

Spaniard

iTrader: (1)

Good one ha ha haha!!! Thats my kind of humor...


SHees.

dgeesaman

iTrader: (10)

You want to create downforce over the rear wheels of a front-wheel-drive car?

You sure about that?

nosispower

My trunk spoiler adds A LOT of downforce to my car, it feels great when I try to slalom on the highway at 120mph.

mansurxk

iTrader: (14)

a little downforce to the rear of your car would help that wheel gap

ti2tmax

iTrader: (18)

I'd like some info on this "splitter" if it's true. my car is stock height but at 110+ the front end gets REAL light. Lowering would help some too I belive..

deezo

iTrader: (3)

Thing is Spaniard, if you want something that works, it's going to make your car look hurt.

Spaniard

iTrader: (1)

Yea, I know- not a big deal for performance even if it worked.. I just dont like oversteering if I can help it.

deezo

iTrader: (3)

It might help to get stickier tires for the rear and see how that works. that will allow for more push (understeer) through the turns.

shavedmax

iTrader: (6)

you only create downfoce when you have air going both over and under whatever it is. think of it like your hand out the window at 50mph. if its tilted one way it goes up, if it tilts the other way, it goes down. doesnt do much when you cup it over your mirror though, does it?

$tillenmax2k

Seems you didn't learn anything from taking all those classes!
The space under our rear spoiler is actually what makes it work. The negative pressure on the underside is what provides downforce and stability.
It cracks me up when I see people post how aerodynamics don't do anything until X mph. Even at 20mph it plays a role. For road cars, 60-80mph is when aero components start to make a difference.
I have a carbon fiber front diffuser on my car from a local maxima tuner, and it makes a noticable difference. It's about 1/2 the size of our hood, so it gives a pretty large area for aerodynamics to work on. It sticks out about .5" from my front lip, and then covers most of the bottom of my engine bay. The shape of it is actually kind of hard to describe, it's a lot more complicated then i thought it would be. If anyone wants to get one, PM me and I can give you more info on the guy to get it from.

BTW- Due to the shape and location of the rear window spoiler, it actually creates lift.

nexgenmax

iTrader: (14)

hope this will help
http://www.absoluteastronomy.com/enc.../downforce.htm

It's correct that for street cars, aerodynamic start around 60mph

Spaniard

iTrader: (1)

Thanks for the info, all-

Deezo- right! I have my sticky tires in the back on my "road wheels" for "insurance" if I have a accident to avoid or something.
On the track I have been keeping the same rubber all round and making sure to have tire pressure ideal for grip for the rear wheels. It might be interesting to consider when/if I go to racing rubber - to get stickier tires for the rear than the front... nice idea... Hoosiers in the back and Victoracers in front!!! I like it!


And now, at the risk of seeming laim, I have to admit- there might be a spoiler that works a bit better and still looks - well- maybe even good..?

Here it is:





J
U
S
T

K
I
D
D
I
N
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Actually, this is the one I wouldn't mind- I think... just mulling it over... not like I have $500 bucks to spend on it...,

dgeesaman

iTrader: (10)

I don't think you even got the point. This car understeers. Downforce at the rear lifts pressure off the front wheels, making understeer worse. At high speeds, it can lead to complete loss of steering. Cosmetic spoilers are one thing, but trust me you don't want downforce on the rear of the car. If anything, you want canards on the front corners to put downforce on the front.

THAT'S why putting a rear wing for downforce on this car, and attempting to driver at high speed is an incredibly stupid thing to do. It reeks of Darwin.

Spaniard

iTrader: (1)

I do now see what you are getting at so thanks for making your point clear. A very interesting point and yes, not one that occurred to me.

You see, Ive been encountering oversteer as well as understeer - so thats why I was asking. Ive been adjusting my tire pressures to non-ideal grip in the front, with ideal grip psi in the rear to prevent oversteer at high speed.
So I was thinking if I got a bit more downforce in the rear, I could "turn up" the grip in the front.

Also, I have a hard time thinking that at even 100+ MPH even a big rear wing would cause 'loss of steering' - at least for someone who has a clue as to how to drive? Let off the gas, (decelaration, increased force on front tires), start to turn, also slows the car, increased force on front tires...

So, not to sound argumentative but thats where im coming from. I appreciate your point though.

Spaniard

iTrader: (1)

Oh yea, and can anyone describe or point me to pictures of canards and splitters?

dgeesaman

iTrader: (10)

- okay, some physics - bear with me now.

A car on shocks is like a seesaw - push on the front tires, the rears lose some grip. And vice-versa. Same goes for left/right. There are two reasons why this will happen - inertial loads and aerodynamic effects.

What you're talking about is inertial - hit the brakes, the car tilts forward, causes a tendency to oversteer. Hit the throttle, it understeers. The maxima in a rolling corner (no throttle or brake) still understeers a little.

The aerodynamic forces are basically constant for a given speed - if you put a wing on the rear, behind the rear wheels, that produces downforce, it will put more load on the rear wheels and lift some on the front. If you're on the throttle and at high speed, that means you have very little force giving the front tires grip, and at a high enough speed it can cause vehicle instability. Instability doesn't mean the fronts lift off, but it means you don't have enough steering friction to keep the car on line if there are tiny bumps or crosswinds. And THEN you go flying/spinning.

On a FWD car, the ideal wing is not behind the rear wheels as it is in the case of a RWD car (in RWD, both throttle and braking pushes the front down and counteracts the rear downforce). So on a RWD car, a rear wing can be functional, but on a FWD car, it's rice (as in, for looks but not function). The stock 'wing' is actually a spoiler - it produces little or no downforce.

So on a Maxima, since you don't see many roof-mounted wings, then the front is the only reasonable place to see them. And the reason nobody makes them is because the Maxima is not built to race at the speeds where it's significant. Try all you want, this is still a FWD family 4-door.

Canard is a wing on the front of the car. Splitters are a form of canard fitted on the side of the front bumper at the corners. The trick is getting them to not ruin the airflow over the rest of the car and cause excess drag. See here for a pic of splitters: http://www.rx7club.com/showthread.ph...ghlight=canard and
here for a discussion of this subject in the case of a RWD car: http://www.rx7club.com/showthread.ph...t=aerodynamics

Dave

$tillenmax2k

dgeesaman- Sorry dude, but you're trying to teach people, yet you don't quite understand the topic yourself. A canard is not simply a wing on the front, and a splitter is definitely not a type of canard.

If you guys want to see what the front (visible) portion of a splitter looks like, go here: http://www.the16v.com/RA03/split/index.htm

dgeesaman

iTrader: (10)

So after all that discussion you come on to gripe about the precise definition of splitter? And you post a link showing integrated splitter/canards to clarify the difference? Thank god someone who knows showed up.

Truth be told, I switched the definitions a little - a canard is any kind of wing/fin/stabilizer on the leading end of an aerodynamic body - and a splitter is a front wing. Either way, a Maxima is too slow and heavy for it to matter. If a Maxima were capable of really racing, it would need a full suspension conversion before aerodynamics are worth worrying about.

Dave

97SEdriver

iTrader: (3)

Dave,
any car is capable of really racing, I've never seen a maxima out there at an SCCA event, or NASA competition event. But several guys on this site, including me, have certainly done NASA HPDE events and over here there's EMRA which I might start next year. Maxima's can consistently beat Miatas and the like on any course with some longish straights, I suck in the infield compared to the Miatas (but I'm still running stock wheels and suspension). And I have certainly hit 120mph at track events. This year the SCCA is trying a PDE at Pocono where you run 2.5 miles of the course. This whole downforce arguement is relevant, but the time it would take to dial everything in is not trivial, so it depends what this guy is going to do.

C MAX

iTrader: (4)

hahahahahahahahahahahahahahah

dgeesaman

iTrader: (10)

Sure, a buddy of mine autox'd his 01 Max SE the other week because his Camaro wasn't fully prepped. I guess if he was a track guy who did this regularly, he still wouldn't put aero mods on it because it would hurt his highway fuel mileage. (remember, adding downforce adds drag - this tradeoff cannot be avoided)

My point is that to do aerodynamics and make it actually work, you need one of two things:
- track time to dial in and let the results judge your changes
- wind tunnel or serious CFD work to make a best guess.

The rear window spoiler in question clearly needs track time or analysis to prove it's utility. It appear designed to sell based on looks and not utility, IMHO. At least its center of pressure is in line with the rear axles, not hanging off the back like I've seen on some other FWD rice cars. But since it is a spoiler, I suspect it could tend to trip the airflow and cause a net lift on the rear instead. It's impossible to know without testing or analysis.

So what I'm saying is that yes, you can race a Maxima, but those racers are generally folks who just getting started and need the car for on-road use as well. And if you're doing that and getting to the point where aerodynamics are of concern, you should pick up another car and start with something RWD and a more racing-like suspension. At least a used Bimmer. The fact that there is no market for functional aero add-ons helps reinforce the notion that aero mods for Maximas are mostly for looks, and maybe tuned for highway feel, but not racing.

Dave

97SEdriver

iTrader: (3)

Most of this stuff is custom anyway, and yes a used bimmer might be easier. But you know that SE-R are in the SCCA races, and so too with Dodge Neons. I know on most days I can still take a SE-R, and unless it's engine has been worked over, it's hitting the rev limiter at like 105-110mph in 4th. Still it might be fun to actually put a roll cage in a max to see how good it really is in some real racing.

$tillenmax2k

Again, you're spreading incorrect info. On most production cars, lift is produced by many things that are also causing drag. It's not too difficult to reduce drag while at the same time reducing lift.

Too continue on-topic discussion, the rear window spoiler produces lift. Reason for this is because it creates a low pressure region over the rear window, which in essence it acting like an airplane wing. That's the opposite effect we want. Low pressure on the top portion of the car lifts it up.
A note about terminology:
Typically the term 'lift' is used when talking about any kind of aerodynamically induced force acting on a surface. This is then given an indicator, either '+' or '-' as to its direction. In racing the term 'lift' is generally avoided as its meaning is almost always implied as positive, i.e., lifting the car off the track. When ever the term 'lift' is used its meaning should be implied as positive force. The term 'downforce', therefore, should always be implied as negative force, i.e., pushing the car to the road.


Maybe some examples will help people understand, especially if you look at the profile of the following cars.
The VW New Beetle creates 742lbs of lift at 124mph. That means it would come off the ground (and take off like an airplane) at 124mph if it weighed only 742lbs. Pretty scary!
The Ferrari 360 Modena produces 294lbs of downforce at 150mph. So it actually gets pushed down onto the road the faster it goes. This is all without wings or any big aero appendages no top of the car.
To compare a car built with the sole intention of racing, the 1987 Nissan GTP ZX-T produced 3,938lbs of downforce at 150mph, and aoround 7,000lbs at 200mph! This is why aerodynamics add-ons must be firmly attached to the chassis, not just the body!!!

An interesting math fact, lift/downforce increases with the square of speed. The same is true for drag. So if a stock maxima produces let's say (just a random azz #) 100lbs of lift at 60mph, it will produce 200lbs of lift at just 90mph, and 400lbs at 120mph. No wonder our cars feel like at high speeds huh?

dgeesaman

iTrader: (10)

A lot of people say that, but there is no evidence to back it up. I'm trying to call you out, but aerodynamics is a fishy subject, such that small things can completely change the results. It's highly nonlinear at times, and unless you have experience experimenting with a particular car, everything is a guess. That's why I made the statement that downforce or lift comes with drag - it's a generally true thing when other conditions are held equal. Certainly in racing conditions - you're trading off top speed for cornering downforce. Problem is it's never quite that simple.

So for example, the rear window spoiler could be inducing turbulent flow in an advantageous manner, where laminar flow would have been higher drag. Or like you said, it could create a low pressure wake that creates a net lift on the rear. But it all depends, and will vary with speed as well. I agree with your assessment that it will result in lift - but it's only a guess.

Dave

rome06

iTrader: (1)

wow those spoilers are ugly as hell