our web server it down, so I can't post pics just yet.

and the prius supposedly has a Cd of .26 also

 

I don't know about the G being bigger Tom. In which aspects? Wheelbase yes but the wheels are so close to the corners it ends up being extremely short. I have parked next to many a G and they are no doubt shorter in height and length. Width I don't know but I'd guess they are pretty close. The track width on the G may be wider but this is again because the wheel are pushed out away from the body so much. Now weight, I will agree the G is heavier. That said, I agree that its Cd is incredible. I've never even seen .27's.

 

Hmm...2005 G35 coupe is 2 inches wider than the sedan, which is 0.7 inches narrower than our cars! And the sedan is about 2 inches taller than an unlowered 4th gen, so that's a huge difference. 2 inches is huge when you're talking about the general appearance of a car. Also the G comes stock at a sensible ride height, not a 4x4 ride height, so that's really more than a 2-inch difference. But otherwise you're right, our cars are pretty big, and the G is still essentially the baby Infiniti in the tradition of the G20. But the G35 just seems bigger than my car....

Get this: the G35 sedan w/aero is 0.26 Cd, whereas the coupe w/aero is 0.28! Probably because the coupe is wider and shorter.

Anyway, let's get this thread back on topic.

 

Nathan I will ship the Lip to you Sat or Friday night with a tracking # which i'll email you with Cool

 

I always forget there is a G35 sedan. In my previous post I was refering to the G35c. I will fully agree that the sedan is larger than our cars. I really don't like the shape of the sedan. I guess it doesn't look fast or aerodynamic but apparently my intuition is way off.

 

just to drag the off topic-ness of this thread ona bit longer, what is Cd? i feel like a total newb when it comes to drag and downforce.

 

coefficient of drag IIRC

 

Cd = Coefficient of drag. The d should be subscript but Sprint hasn't enabled that option.

It's just an index of how much overall drag the car produces. Higher Cd = more drag = worse aerodynamics. A Cd of 1.0 probably has some significance at least as a benchmark. Yeah, it does, see here: http://en.wikipedia.org/wiki/Drag_coefficient

 

ok, cool, ive only heard it refered to drag coefficient, never the other way around, so i didnt put it together, but thats a pretty dang aerodynamic car.

 

I think areo dynamics fits in this thread pretty well... maybe a bit of a stretch.

just talked to the machinist tonight, sounds like we'll be talking about prices in the next week or so. We threw in a few ball-park numbers, but nothing I can say yet until we do an analysis based on selling about four of them. (which is about right for starters) I finnally got his email adress, so I'll ship him this thread address.

BTW, somewhere in my notes I have a calculation that: based on Cd, and frontal area you can figure out how much HP is required to go a certain top speed. I'll try and dig it up when I get time.

Nate

 

Well, I found some notes from when we were designing the maxima diffusers and splitters. A GT car with a Cd of .50 and frontal area of about 19 Sq f requires about 70hp to go 100mph, 110hp to go 120mph, 180hp to go 140mph, and 250hp to go 160mph.
I don't remember what Top Element calculated as the CL (coefficient of lift, negative in this case) to be, but he said that the force is proportional to the square of the speed. So in other words, if you make just 20lbs. of downforce at 50mph, you'll make 40lbs at 75mph, 80lbs at 100mph, and a whopping 160lbs. at just 150mph. That may not sound like much, but considering the car makes positive lift in stock form, it's quite an improvement.

 

That's really good info. I didn't know about the downforce being a factor of the square of speed, that explains how the car feels at 120!

Nate

 

Drag is also proportional to the square of the speed, which is why it takes only 70HP to go 100MPH in your example, but 250HP to get to 160MPH. Cool cool.

One thing to think about is, do you ideally want the downforce to get really high at higher speeds? I mean, would you ever want 3000 pounds of downforce, or would that make the car too low and put unnecessary stress on the suspension and tires and result in more drag because there's so much weight pushing down?

I can see that you'd want to tune the splitter and any other devices accordingly. If you are mainly driving at 45 to 75MPH, you want more of a downforce bias; if you are mainly racing or driving over 100MPH (Broaner) then you'd want e.g. a smaller splitter perhaps. If that sounds wrong, it could be; just a thought. Certainly, you do need more downforce as the speeds go up, I'm just saying you may not need tons more.

 

not neccessarily a smaller front diffuser, but maybe a rear diffuser so that the air underneath the car can have a more streamlined exiting speed, which means the air going above the car has more pressure = downforce.

any type of downforce is going to be beneficial at our user levels. Until a maxima is hitting 130+ mph constantly at speeds like the F1 and race cars, there shouldn't be a great worry on the amount of downforce created and controlled through wind tunnel testing, etc.

 

are these worth buying?

http://carbon-creations.com/shopexd.asp?id=4452

http://carbon-creations.com/shopexd.asp?id=3391

http://carbon-creations.com/shopexd.asp?id=3361

http://carbon-creations.com/shopexd.asp?id=3390

 

I've been thinking on this issue. If this splitter does so much for frontal down force it is going to make the rear real snappy. I've experience the tail sliding on me at about 130 and it wasn't fun. I lifted the throttle too abruptly on a sweeping turn and I almost ended up backwards. Got back on the gas and it stepped in line.

 

there really isn't an exact measurement to how much downforce you'll be adding with such an addition to the front of the car. IMO, to say that the addition of this would disrupt the balance of the car is far fetched.

going into a turn pushing a fwd car to its limits and letting off the gas at that speed, any tail sliding would be obvious. Letting off the gas or braking at those points is what ultimately disrupted the balance on your car

 

i've got a really good article at home on downforce and it shows how it's applied to cars, it's got a good picture on how it works and how the downforce is directed, i'll post it when i get home tonight if i can find it (i'm at school)

 

group deal on our local wind tunnel testing facility

 

This is what i am talking about. too much down force on the front may be more bad than good....concidering there is nothing the rear of our maximas to hold em down....

im still in suport of this, but i have my doubts still....

 

No no no. I haven't seen pics of nateplaysbass' whole splitter, but I'm almost positive it doesn't make any downforce if it's just a flat bottom. Our splitter was designed to reduce lift as much as possible, with the limited shape and area there is under the front of our cars. And even with brake ducts, strakes, and venturi shaping, it's hard to design something without compromising ground clearance. So it simply reduces some lift created by the stock vehicle shape. Even so, it still makes a noticable improvement.
In order to produce actual downforce, the lift must be overcome, which is over 200lbs @ 100mph for most road cars. For example, the VW New Beetle would come off the ground at 125mph if it weighed 740lbs. So as you see, it's very hard to make a maxima produce much, if any, downforce at all. No need to worry about aerodynamic imbalance.

 

I think we need to define our terms here a little bit. Lift is the force that acts on the car as a result of its shape that tends to pull the car off the ground or push it to the ground; lift can be negative (i.e. the Ferrari 360). The downforce is the force produced by the splitter or what have you that tends to push the car down to the ground. Our cars naturally make positive lift at speed. The splitter always makes downforce, which just counteracts some of the positive lift. There may still be some residual positive lift at any given speed, and more at higher speeds, but it will be less with the splitter on there than before. The amount of positive lift created by the car is related to the speed of the car, as is the amount of downforce produced by the splitter. So the more positive lift the car creates, the more downforce the splitter produces, which counteracts the positive lift. When the positive lift created exceeds the weight of the car, that's when you start to take off like the New Beetle

 

I have a general question, I have KYB AGX and a FSTB and my suspension is very Stiff, and i don't have a Drop YET and when i go 80+ MPH i get viberation. Do you guys with the similiar suspension get viberation? Now, I'm think it's because I don't have a drop so the air flowing under the car is causing my car to viberate because it's stiff and there is no flex. I don't know much about this, i checked my tires they are fine but is this common ?

 

That sounds more like a dented rim than aerodynamics. a small dent is not noticable until higher speeds like that. I get vibration around 60, but that's because I have a dented rim, the vibration stops somewhere around 80.

Thank you for defining the terms bullfrog.

I'm going to do some more research on downforce and it's effects on the whole car. I'd dare to veture that since the splitter is not allowing as much air to go under the car at the front, there is not as much air under the car at the back as well for this reason. However, air could easily come back under the car behind the front wheels.
Nate

 

I'm going to check my tires again i might have a Bulge in the tire because i know i don't have a dented rim. Hey having too much air in a tire could that cause viberation and a rough ride feel every damn bump

 

But look at this diagram again:





Even though less air is passing under the entire car, the splitter's horizontal surface area is only at the front of the car. It's this that the higher air pressure on top is pressing down on (Bernoulli principle). Even if you have a venturi at the front of the car, that doesn't affect the flow/speed behind it much, I suspect. Once it leaves the venturi it slows down to the speed of the surrounding air. I think the botom line is that a front splitter only produces downforce at the front of the car.

 

I would imagine the splitter doesn't directly increase rear downforce. It would make sense though that it deacreases the quantity of air travel under the rearward section of the vehicle and therefore slightly effect rear forces.

 

Did anyone know that custom maxima sells wind splitters, I just visited the website and they are 239.00 dollars Man i use to shop there till there prices Look way out of the ordinary

 

Custom Maxima sucks. 'nough said...

 

That's for a two piece set. Not even a real splitter, just the outside corners. more for bling than for function.

I'm trying to get Mark (the fabricator) to come and read this thread, so everyone say 'hi', and welcome him.

Nate

 

hi mark, make me a splitter!

 

hi mark! make me a splitter also!

 

Hi Mark need splitter man plus Nate that lip is on it way i emailed you tracking info

 

There's a large potential market on the Org for this splitter, so get fabricating.

 

trying oh so hard, this might still take a while.
Nate

 

nate did u get the lip today

 

nice I really like it.

 

i want a splitter Nate so make me one to man.

 

MaxDaddy, yes, I got the lip. hopefully I'll have some time in the next week to take pictures of my current splitter with the stillen lip for comparison. we'll see what you guys think of the looks.

Observations: now that you guys mention stability in the back of the car, I am noticing that the rear does feel a bit unsettled compared to the front of the car. I'm not sure if this is because I'm used to the stability of the front, or if it is actually and worse than it was originally.

Nate

 

guess its time for a big ol ricer wing, one of the few that actually are angled right to provide downforce, and maybe a rear diffuser if that feasible