why ram air is a myth

[Brazen6.0]

really good scientific argument about why ram air for cars do not work.

you "ingueneers" will love that one! :D

http://www.vetteguru.com/ramair/

[Ponyperformance6]

I'd say he is full of it

"Ram air is a myth because it does not exist, for the following reasons:

- Air is incompressible at any automobile speed., meaning that the kinetic energy of the air cannot be used to compress the air and raise the static pressure. "

If i remember right air is only imcompressible nearing Mach speeds, thus the formation of wave drag and more importanly a shockwave that forms on a wing and causes the center of lift to move rearward on a wing resulting in mach tuck.

[Brazen6.0]

depends....the concorde used ram air above mach 1 to bypass the engine turbine, basically becoming a ram jet...I think the "ram effect" that a scoop can give you, if any, is little that the effect alone wouldn't warrent a gain in hp. I do belive the 30-50 deg difference in temp is what make most "ram air" effective.

[OnequickZ28]

I also think he is full of it.

To my understanding ram air is supposed to force air into the cylinders. Using simple logic, if there are opeings in the front of the car and the car is moving, air WILL be forced into those openings. OF course ram air would not show any horsepower increses on a normal dyno, the car needs to be moving to show an increse. That's why some dynos have big fans in front of the car. And lastly, the LS1 Trans ams are usually faster than an equivlent Camaro. I wonder why?

[HORSEpower]

I think he misses the point a bit. Yes the nozzle is in the incorrect shape, but the car isn't designed to get the energy from static pressure. I believe that a slight dynamic pressure can help the engine overcome bottlenecks in the intake system. The engine will not have to work as hard to get the same amount of air in, even though it will not get any more air.

Kurt

[Ponyperformance6]

there are some other reasons why a ram air effect must exist to a certain point, pitot tubes for example along with the way turbines work require ram-air pressure.

[LethalBird]

Is the sahker hood on the Mustang considered a Ram Air? why did Ford bring it back to the market after 30 years?

[Brazen6.0]

they brought it up cuz it looks bad ass :)

Turbines do not work on ram air but compressed air by the compressor section(s)

[HORSEpower]

there are some other reasons why a ram air effect must exist to a certain point, pitot tubes for example along with the way turbines work require ram-air pressure.

That's the whole point, dynamic pressure won't increase the amount of air entering the piston, it has to be static pressure.

Kurt

[Ponyperformance6]

thats understandable, but its still more air that goes into the airbox and at a higher pressure so it helps some,
and Eddie yes they say the MAch 1 hood is a functional ram air system

[Lawman9C1]

I have done all 3 types on intake on my car, Factory, Cold Air, and "Ram Air"

There was a serious jump on both systems from the factory air box, but that has less to do with ram air and more to do with the fact that the Factory Airbox intake port actually has less surface area then the MAF sensor.

The RAISS that I run nows only real advantage over the K&N is that instead of being shrowded behind the Drivers side headlamp its mounted directly infront of the intake manifold with only 4 inches of distance between the filter base and the Throttle body with the MAF taking up the extra center distance. It doesnt get faster as I get faster just increases throttle responce because of the distance the air needs to travel and the less energy required for that air to match the sudden opening of the throttle body.

And like JB said High Bypass Turbofans run off compression from internal sources, the only engines that run off of air compression caused by aircraft velocity are RAM Jet, and experimental SCRAM Jet Engines.

Drew

[OnequickZ28]

There is a good explantion at this website.


http://web.camaross.com/forums/showthread.php?s=&threadid=166936

Look for the post by Injuneer.[/url]

[LethalBird]

Is the ram air on the Mustang with that shaker hood a myth too?
Just wondering

[Ponyperformance6]

Eddie, the guy was saying all is a myth

[toastychicken]

So is this guy implying that every company that's ever given a RamAir option and has shown improved HP/Torque numbers is falsifying data? That's an awful lot of lying going on, especially for (for me anyways) a mere 5HP difference.

[Brazen6.0]

he did point out that the WS6 got more hp dues to a less restrictive intake box and better exaust...which is also what pontiac says in the fine prints (according to him).
I'd like to see some "engenieers" point of view on that...if you think about it, that "little" ram effect you get at 90mph reall has to "push" that air thru alot of stuff! filter, intake elbow, tb, intake and valves...so in a way its understandable that it might not do anything for power....now if you had it directly routed to the TB with scoop, who knows!

[mrwhistle]

why don't we test it out. I bet if you put a piezo pressure transducer at the end of a tube you could find out if there is a pressure increase at the base of the tube. it seems to me that if you point the tube directly into the wind as you drive down the 95 at 100 miles an hour that if there is actually an increase in pressure it would show up.

[HORSEpower]

Yeah, but that would be an increase in dynamic pressure, not static pressure. You would have to do some tests at a track, and check you mphs.

Kurt

[mrwhistle]

see here's the thing I don't understand, at some point dynamic pressure becomes static pressure right? I think the transition point is when there is a constriction in flow, if the flow out an orifice is less than the flow into and orifice, static pressure should develop. I think this guy is talking about bernoulis principal where the pressure of a fluid that traverses a greater distance is at a lower pressure than slower moving fluids. but tell me, does a fan not generate dynamic pressure? if that fan is really big and directed into a closed chamber you end up with an axial air compressor, which generates static pressure. I have a feeling that the question of whether or not ram air works is more dependent upon the flow of air into the intake, which is under almost constant vacuum in na cars.

[HORSEpower]

An axial compressor works totally different from a fan. An axial compressor runs the air through a set of moving and static blades, a fan just whips it up. In order for the air coming out of a fan to change from dynamic pressure to static pressure, it would have to pass through a divergent nozzle.

Kurt

[Deebo]

HEADACHE :dunce: .... NEEEED... ADVIL....

:D

Ram air has been a pontiac brand name gimmick item since the Goat... i dont think it has much to do with compressing air for a denser charge, but more to do with routing fresh air quickly into the motor. which is cooler and denser than the warm air found in the motor. Like Cowl induction for the first gen Camaro's. Also the air plumbing for the ram air T/A's is very short, straight from the exposed filter to the MAF to the TB...

Deebo

[Cheesesteak]

just to set the story straight, eddie, you say a jet engine works by compressing air only through the compressor stage, and that ram air has nothing to do with it...

every jet engine gains from what is called the "ram air effect." the air is compressed before the first compressor stage in the intake of the engine when the aircraft is moving and this increases the thrust of the engine because of increased pressure at the combustion chambers. take a look in our turbines text. another thing, this guy claims that air is incompressible below mach 0.5. that is only a practice used by engineers and such to simplify calculations. will hit the nail on the head when he talked about pitot tubes. this should prove that SOME compression MUST exist at ANY speed.

this is not to say, however, that i think ram air on cars actually works. theoretically, it should cram higher density air into the throttle body, but in any application i've ever seen, it doesn't seem to be done efficiently enough to take advantage.

simple solution: mount the intake section of a turbojet engine directly to your throttle body, and nobody can say you don't have ram air :D

-josh

[Ponyperformance6]

LOL @ Josh !!

I would argue more to the point that an increased air density isnt really the benefit that Ram air provides... but more the difference in intake charge temperature versus any other type of intake i.e. underhood, fenderwall, afterall Ram Air is at ambient temperature.
Will

[HORSEpower]

Again, pressure and density are 2 different things. Will did not hit the nail on the head with the pitot tube point. A pitot tube reacts to dynamic pressure, which is not related to static pressure.

Kurt