The air you are feeling on your hand is due to the movement of your hand thru the air, the "air" itself is not pressurise. What a turbo or blower does is "pressurise" the air. In order to have "pressurised air" via a ram air effect you need to be very close to Mach1 where a pressure wave will form and then have a way (aka design) to capture that pressure and route it where you want it to be (like a RAM JET). In order to make more hp, you need to "pressurise" your air.
Look at what a turbine or roots blower does, its function and design and you will see what I mean.
While you have your hand outside the window, you are measuring both static and dynamic, just like pitot tube and static port calculates your air speed, by a function of the difference between Dynamic (at the pitot tube) and static (at the static port on the side of the fuselage)

The reason why you do not feel the "air" on you is because the pressure outside of your boddy is equal to the pressure inside it. For exemple, take a hose, and go in your pool, goo down a few feet, and try to brease thru that hose connected at the surface. You can't. The pressure around your boddy is greater than the pressure inside of you. This is why when you scubba dive you have a regulator and pressurised air so that you may breath like normal.

But like CT said, and he is right, is that with a good "ram air" system (which by the way is GM's little market ploy name calling) you isolate any heat from the engine and thus are able to get embient air directly into your intake, thus creating more hp.

By all means, if you like to belive that your Ram Air is giving you PSI, go for it, hey some believe in the Leperchaun...

Or maybe we'll just open a new thread and we'll start throwing graph, equations, and some fuid dynamics ...it is up to you, I'm game

 

You only need to go mach1+ in a ramjet. At lower speeds, the equivilent is a pulse jet where the 'pressure wave' is emulated by a reed valve. Turbine jets use.. you gussed it, turbines.

We use none of the above, good ol' gas burning pistons, mach anything has nothing to do with our application.

Moving air is just that, moving air. Wiether by fan/turbine/roots blower/your mouth, it all creats moving air with pressure, the only differance is the amount.

I know most of this, I am a certified diver, a lot to do with pressure on your body.
If you don't beileve that a froce on a surface is pressure.... ask a 6th grade teacher. It is so incredibly simple. A force on an area is PRESSURE, which happens to be messured in PSI. But to make you happy, it will confirm it with my fluid dynamics prof., I'm an engineering major at GMI, we know cars just a little bit.

You don't have to believe it, but you also don't have to beileve the earth is round.

EDIT: Just thought of this on the way back form class. Has anyone ever tired to open a garbage bag by moving it through the air? Well, when the opening catches the moving air, it creates pressure in the empty bag. The pressure is 'slightly' higher than the ambiant pressure. This slight pressure differance causes the bag to baloon and become open! It's that simple to prove. Now try that going 60mph. That bag is going to rip! why? Pressure, that's why.

 

and I have a degree in Aeronautics and a Masters in it and I am suround with Aero Engineers as well with Engineering Physics, all grads from Embry Riddle, the number one Aero Engineering school in the nation, WE know airplanes and WE know Ram air.

So now that we have established our credentials, go ask your fluid dynamics teacher if you can get any air compression via ramin effect at let's say from 50 mph to 140 and you let me know.
Also you will find out that, you will not be able to "compress air" by just speed until you get a shock wave. This self explanatory, no 6th graders will undertand that tho, but we all do...
You are talking about a force on a surface, which is different than compressing air, which is what RAM AIR is. Of course I am not going to disagree on your Pressure forumla, never the less, by sticking your hand out the window you are feeling the difference of "pressure" between dynamic and static, not just one or the other, you have to have both.. Also, while you stick your hand in the window, you also are geting drag from your hand and air resistance which is pushing your hand.

 

here we go:

http://www.grc.nasa.gov/WWW/K-12/airplane/hisup.html

something on ramjets:

http://www.grc.nasa.gov/WWW/K-12/airplane/ramth.html

on more on ramjets:

http://www.grc.nasa.gov/WWW/K-12/airplane/ramjet.html

read the above. Strangely enough, all them GM/Ford ram air intake don't quite look like that....hmmm



this is way to much fun...I should really go back to more boring work related things ;-)

 

Yeah I guess it's agreed it's not "ram air", it's more like "pushed cold air". That sounds about right. BTW thanks everyone for all of their input.

 

ok ok one more:

Flight speed
Ramjets generally give little or no thrust below about half the speed of sound, and they are inefficient (less than 600 seconds due to low compression ratios) until the airspeed exceeds 1000 km/h (600 mph). Even above the minimum speed a wide flight envelope (range of flight conditions), such as low to high speeds and low to high altitudes, can force significant design compromises, and they tend to work best optimised for one designed speed and altitude (point designs). However, ramjets generally outperform gas turbine based jet engine designs at supersonic speeds (mach 2-4). Although inefficient at the slower speeds they are more fuel-efficient than rockets over their entire useful working range.

now granted, this is rocket science, but understand that if ram air was able to work at our speed, you would bet that all jets airplanes would have that by now. It isn't. Remember now, we are talking about compressing air via speed and speed only (which is then ducted and redirected according to very precise physical and mathematical formulas into what is called a ramjet).

So, if you were to manage to get our cobalts to go about at least 600mph, and have your "ram air" intake model after the above posted sites, then I would shake your hand, and ask for a ride, because it would be one hell of a ride...

so, to conclude, GM's Ram Air? not so much, GM's Cold Air Induction, yes defenetly. More power because your outside air temp doesn't rise as much as let say an under the hood filter, thus the extra power is a relation of temp difference of air, yup no prob with that. Compressing the air with a vulgar scoop, thus increasing power due to raised compression, no not so much

 

one of the cooler threads ive ever read..

 

Yeah, very informative and nightmareRacing is an animal with the facts.

 

also, if the mods would like to, I wouldn't mind sumerise this hole thread and slap it on the FAQ's or some other part of the board, so that once and for all the myth of RAM AIR is over....

 

you all got me rollin' (on 18"s yo lol --sorry--)

To supercharge means to fill beyond its actual physical capacity. Any device that does this to an engine is a supercharger.

There are two main types of supercharger defined according to the method of compression. Positive displacement and dynamic compressors.

[edit]
Positive displacement
Positive displacement pumps deliver a fixed volume of air per revolution at all speeds. The device divides the air mechanically into parcels for delivery to the engine, mechanically moving the air into the engine bit by bit.

Major types of positive displacement pumps:

Roots
Lysholm screw
Sliding Vane
Piston
Wankel
G-lader
(Positive displacement pumps are further divided into internal compression and external compression types.)

[edit]
Dynamic
Dynamic compressors rely on accelerating the air to high speed and then exchanging that velocity for pressure by diffusing or slowing it down.

Major types of dynamic compressors:

Centrifugal
Multi stage axial flow
(Note: Comprex superchargers do not fit neatly into either category, being part fish and part fowl. The Comprex design uses the exhaust gas to directly compress the incoming charge.)

Superchargers are further defined according to their method of drive.

Now, the interesting thing to note, and remember, is the fact that you must "speed up the air then slow it down" to have a trade off.

So, this also concludes the Ram Air thread because non of them ram air intake are designed to speed up then slow down the air in such a fashion that it would create pressure.

Thank you very much, I'm hear all week

is that enough info? or should I continue on? yall tell me now...I'm having a blast with that stuff (I'm such a geek at times lol)

 

Like I said bro, you are an animal. Yeah the moderators should make this a FAQ sticky.
There is more info in here than panties on the walls of Coyote Ugly.

 

hey thanks bud!
I will sumarise all this into one shorter thread, probably do it tonight when I get home (it'll give me the chance to throw some basic formulas as well...ya know the ones you remember for the test but then soon forget )

I've seen this discussion in so many forums, it is insane....

 

HOW DOES A RAMJET HAVE ANYTHING TO DO WITH THIS???

Ram jets are a form of ROCKET. Rockets use oxidizers in thier fuel. THe only thinkg different from a ramjet and a rocket is that a ramjet uses air as the oxidizer, but the only way to get that much air is at high speeds. This is good because rockets can be lighter with no need for an oxidizer. This has NOTHING to do with internal cumbustion engines. Ramjets burn liquid hygrogen. I must have missed that feature in the owners manual. The comparison of these two types of propulsion is apples to oranges, AKA almost pointless.

Here is some simple aronautics. Drag is caused by what? Molecules smacking into the front of a plane. What does this mean. The pressure in the front of an airplane rises, as the rear of the plane stays nutral. This pressure differeance exerts a force rearward, in a force that we call drag. Simple
And beacuase everyone loves links:

http://selair.selkirk.bc.ca/aerodyna...rag/Page2.html

http://en.wikipedia.org/wiki/Drag_%28physics%29

And my favorite about air colliding with a surface to create pressure:
http://en.wikipedia.org/wiki/Kinetic_theory#Pressure
I still say there will be SOME pressure differenace! I'm not saying that it will be subsanatial, and prabably barely measurable.

 

I don't think you will get this thru your head, but that is ok, now, time for you to be corrected on a few facts you've just stated:

RamJet engine is not a form of rocket, it is a jet engine
The high speed is to produce a pressure (see the above links for further explanation) like a compressor stage would on a jet engine (it replaces just that)
A good example of ram jet was the SR 71, with an adjustable engine inlet cone that would keep the shock wave at a given point so that they would be "tunable" for multiple speeds and Altitude.
Forget that we are using pistons, you are not talking about pistons, you are talking about creating pressure via a scoop mounted on your vehicle, in the intent to create pressre much like a supercharger would, but instead using speed (velocity if you will) as a "tool" to creat it, for the result of increase hp.
I have used many facts and figures that prove you wrong, that you cannot produce such effect, regardless of the after use.

You are talking about a "principle" and a principle does not care if it is on a car, a plane, a bike etc...it remains the same.

 

I'll tell you what, I am going to try tp get around to building up a rig to prove it by this weekend. IF I'm wrong, I'm wrong. But i don't think I'm going to be

 

k sounds like a plan to me!

here is also what I will be looking for, from you and your rig:

A complete details of the "rig" itself
Measurments of Density, temperature and velociy of the air a all crucial points of the "rig"

Also will need gauges locations, and also gauges certifications of any kind that pertain to what we want to measure.

We're going to handle this a la professional style, and I will then submit what you have found to various key people in the field of Aero Engineering to validate your experiment (because I feel compared to them, I haven't enough knowledge to do so)

We will then discuss your results

Do not forget that if you were to find positive results, to intergrate them with the production of hp on your car of choice, theorical increases and hard data will be needed.

Also, to make this more fun, I will say that you are still wrong, and that the changes in "et's" that everyone are seeing from their scooper upper are mairly an air temp difference, for the results encountered are very similar as of running between hot and cold days.

looking forward to it!

 

Actually, at the time being, I don't have access to any certified gauges. I would really enjoy doing this very perfessionally, but at the time being (school term) It is hard to do so. I work at GM and do have access to very very nice equiptment, but not right now. For now it will be very much 'ghetto' rigged. As per my theory, it will show a pressure 'change'. As for actual pressure, I will have to leave undetermined as I will be using a $60 POS boost gauge. I am interested if there is a positive pressure change period. If the needle moves up, I will be satisfied.

 

Removing the light would not give a "Ram" effect at all unless you were doing 200 MPH.

The pressure is free to **** out of every crack.

As far as cooling.. Minimal improvements...

As fas as Rain... Better get a new engine ready.. Hydrolock...

 

well but that is where it is geting complicated, because now it is going to be a POS gauge, so you're not going to prove anything. What you are going to disprove is that the increase power you see at the track is by far not from any pressure effect but a temp difference. But, by all means if you're curious enough to actually rig it, that would be sweet! I'm still game!

 

add 400mph to that figure you "start" to see something, ref. previous post and links

 

also, had a buddy who claimed that his nitrous kit would raise the pressure in his intake, and hooked a boost gauge to his intake...he was highly disapointed by the results...aka it read 0...

 

and actually I have some idea of what you are going to do, and what you'll end up seeing is either a dynamic pressure change, or a pressure change done by the molecule pushing onto a surface....which neither apply to our discussion of ram air

but hey I love riging stuff up...did it with my roomate, home made lequide rocket motor using nitrous and 116 octane...heheh it was "interesting"

 

If my intake read 0 that would be AWESOME! because I'm quite sure it would read somewhere in the vacuum, prolly more than 20psi

 

so, Mods, should I post a summarised version of this in say the FAQ's?

 

what would be cool is to have a large lightweight tube running throughout the whole underbody of the car containing -40 degrees air that is controlled by a freezing system in the front where the air comes into the hole and is instantly frozen by a method unknown to me, then delivered to the supercharger. so no matter what degrees it is outside you always run a constant PSI for the super and it'll be nice and cold.