Skeedatl

Too bad the WS6 (or any other street ram air application) doesn't use a divergent air box, proving you full of crap. You're so full of crap your eyes are brown.

harddrivin1le

It doesn't have to use a divergent air box in order for static pressure to rise.

Velocity SLOWS throughout the air intake route....thereby INCREASING static pressure. :banghead:

harddrivin1le

Do rear lip-style spoilers create downforce at "street speeds?"

(I'm guessing that you'll say, "no.") :lol2: And you'd be ~ correct - if you never exceeded ~ 60 MPH.

According to you, they must not work below "Mach 0.5," since air is "incompressible" below that speed. :grenade:

Skeedatl

No, lip spoilers don't do sh!t at street speeds other than look good...every the NSX ripoff spoiler your 1LE has.

harddrivin1le

The 1LE does NOT have a proper lip spoiler...

Define "Street speeds."

Modern performance cars are bumping 100 in ~ 12 seconds or less.

Norse396

Hey brain dead, keep me out of this one.

Try driving that combined value at the same time...

Skeedatl

Bzzzz, wrong. You don't even understand the concept of static pressure. With your logic what's the difference between the B.S. of slowing air in a ram air box, versus any regular air box?

Answer: ZILCH.

The concept of ram air is not based on Bernoulli. The concept of ram air is converting dynamic pressure into static pressure through compression (which is where the term RAM air comes from). And there is ZERO perceivable compression at street speeds...which is why ENGINEERS (unlike you) drop this factor from calculations...because the impact of it is negligable...and CERTAINLY doesn't contribute to gains in HP....that is unless you build a back seat only swap 300MPH Slomero.

Skeedatl

Your 1LE wouldn't run 12's off a cliff in a hurricane, especially with your benchtop racer a$$ behind the wheel. There are DAMN few factory cars capable of running 12's...and DAMN few driving around on the streets at 100MPH.

harddrivin1le

Define "street speeds."

And define "significanty higher" (re: compression ratios: aluminum vs. iron).

Your original claim was that ram air was a "myth" @ anything below MACH 0.5.

That is clearly WRONG. It yields quantifiable gains as speeds that are but a fraction of that.

harddrivin1le

The air entering the intake of a "ram air" system is traveling at a much higher rate of speed than it would otherwise be traveling in a "regular air box."

For any given fluids system (pipes, tubes), what impact does a faster inlet velocity have on pressure drop?

svtmike

Can't we all just get along?

Skeedatl

Yeah right, fractions...170 and 300MPH.

Puff puff give. Whatever dumbass.

Tell us again how aluminum heads can't tolerate higher compression that iron.

Tell us again how it's only a cam swap to get a Slomero into the 10's.

Tell us again how V is velocity in the Combined Gas Law.

Tell us again how many motors you built.

Tell us again how may dyon pulls you've participated in.

Tell us again how many passes you made at the track.

Tell us again how 300MPH is a street application.

Tell us again how HIDs suck.

Tell us again how paper outflows cotton through their life cycle.

Tell us again how the center of mass for a small wheel is in a different location than on a larger wheel.

Tell us again how you took 1 year of fluid mechanics and are an engineer yet confuse the most basic engineering concepts of the Combined Gas Law, Bernoulli's Principle and centers of mass.

Tell us again why you got banned from the TSX forum.

Tell us again why you troll the Acura TL forums and yet don't own and don't plan on owning a TL...rather slam the TL any chance you get...while driving what is arguably the biggest POS GM has ever produced and thankfully CANCELLED.

All you do is cut-n-paste crap you haven't the faintest understanding of.

We all need another good laugh from you.

harddrivin1le

The air entering the intake of a "ram air" system is traveling at a much higher rate of speed than it would otherwise be traveling in a "regular air box."

For any given fluids system (pipes, tubes), what impact does a faster inlet velocity have on pressure drop?

Skeedatl

:lol1: :lol1: Holy crap! Dumbass, you aren't going to get any higher static pressure through Bernoulli's Priciple than still air. Where the hell did you get your degree? Cracker Jacks? So your whole argument is that after all the ramming...the air is going just as slow as the air from a conventional airbox. Wow...you're dumber than I thought. I thought you were stupid with claiming Bernoulli's Principle is the physics behind RAM air...this takes the cake.

You aren't going to have a slower air stream than what the motor is taking in. Yet again, another example of you talking out your a$$ while not understanding ANYTHING about the subject.

harddrivin1le

The faster moving air (@ the inlet) will result in a LARGER dynamic pressure drop, which will yield a HIGHER static pressure.

And the engine can only inhale so many CFMS of air...

Skeedatl

Bzzzzz, wrong. You aren't going to get higher static pressure through Bernoulli's priciple than with STILL air. Whether in ram air, or through an air box, the air going into the motor is at the same velocity, thus the same static pressure.

Ram air is NOT based on Bernoulli. It's based on COMPRESSION...that is static pressure HIGHER than natural still air...which effects at street speeds is so small as to be inconsequential.

Where were you when I did the math showing this...and you even agreed with it. That it's COMPRESSION, not Bernoulli's Principle that is behind the failed concept of street ram air.

The last line of your statement is why Bernoulli's Principle has ZERO impact on ram air.

harddrivin1le

Delta P is proportational to Velocity^2

And Bernoulli clearly demonstrates why static pressure RISES as velocity falls.

DonVogel

Define street speeds.

Skeedatl

Below 90MPH. Everyone knows that ram air works at 300MPH.

harddrivin1le

Your earlier claim was that Ram Air did NOTHING "below Mach 0.5"

90 MPH is a lot slower than Mach 0.5. :lol2:

Skeedatl

Duh...but you aren't going to get a higher static pressure than air at ZERO velocity. Bernoulli's principle states that air moving at the same velocity has the same static pressure.

So as far as ram air goes...Bernoulli's Principle is irrelevant as the air is traveling as the SAME FINAL VELOCITY at the throttle plate.

Skeedatl

No I said you don't really start seeing the measurable effects of ram air until Mach .5, which after I showed you the math you abandoned your WS6 articles to those of 170MPH motorcycles and 300MPH airplanes....neither of which are street applications.

harddrivin1le

What makes you think that the velocity is "ZERO?"

And why are you claiming that it's "at the same velocity" in the next sentence?

The net result of RAM AIR is attributable to a combination of SOME compression and the Bernoulli effect. The net result is a quantifiable gain in power at speeds that are far less than "Mach 0.5."

And THAT was your original claim.

Skeedatl

Do the math for us then. :lol1:

So us that 2 columns of air traveling at the same final velocity through the same space (like that of the throttle body) have different static pressure.

It's not Bernoulli, it's compression that is behind ram air...and there is no appreciable compression below mach .5...which I've already shown you the math for but you obviously don't understand.

harddrivin1le

Any intake system causes a NET DROP in velocity (and, therefore, dynamic pressure). That means that static pressure at the end point of said system MUST rise.

A higher inlet velocity (courtesy of RAM AIR) will further magnify that effect because the drop in Pdynamic is proportional to the rise in V^2.

Norse396

Here ya go!




Start, now! 1le, I can post a link if you have trouble with them.

Skeedatl

It rises more because it was lower to begin with...because it was moving faster.

You have 2 columns of air through the same space. One going 100 the other going 150. They'll have different pressures.

If you slow them both to 50, they will both have the same static pressure. It is irrelevant to the engine what their initial static pressures were.

However, what you do have is compression. At street speeds, the amount of compression is so small that it is ignored, but at faster speeds like 300MPH, the effects of the WORK done on the air to compress it becomes an amount significant enough to matter to the system. Mathematically at EVERY speed there is compression of the air, but the amount of compression is square of the change in velocity. So between 25, 50, even 100MPH, there is NO APPRECIABLE COMPRESSION of the air, no matter what some cheap flawed experiment shows...the math shows different. However at 300MPH, you start to see compression of the air that can contribute to gains in HP that aren't attributable to simple CAI effects or better airstream controls.

Not until 500MPH for example are you going to see PSI increases above normal atmospheric of even the smallest lamest turbos.

Bernoulli's Principle has ZERO bearing on ram air. It's compressing the air by stopping it from such a high velocity like 300MPH that it's static pressure is raised ABOVE that of still air. It's not Bernoulli...it's the WORK done on the air by the air behind it...ramming it. Bernoulli's Principle dictates that you can not get higher static pressure from still air by slowing it. You can't go below ZERO velocity.

Now if you can't understand these simple concepts (especially seeing as you claim to have taken a year of fluid mechanics and also claim to be an engineer)...you are a lost cause.

Either way I'm done with this thread and this topic. You still want to believe that the WS6 ram air is so bitchen...so be it. You're the sucker.

Skeedatl

:lol1: He won't have the answers until he can cut-n-paste 'em from ya.

DonVogel

It has been over 20 years since I've done any HVAC design; but as I recall, the velocity pressure of air at 4000 ft/min would equate to approximately 1 inch of water (air pressure); and also that change in velocity pressure increases in square proportion to change in velocity.

4000 ft/min = ~45mph.

90mph is ~2x that speed producing ~4x the pressure, ~4" water.

I wouldn't call that pressure trivial by any measure, even after you adjust it for reasonable losses.

Of course 90mph is rather trivial in his LS1.

~135 = 3x45 ; 9" of water

Its velocity pressure in front of the airdam, static pressure as it is slowed in the airbox. But its positive pressure across the engine that wouldn't exist in first gear.

If thats not going to make some extra HP, I'd appreciate it if you would explain why.

Skeedatl

Here are some sample calculations as I had originally posted the. You can see how tiny the difference in pressure is even at very high automotive speeds (125MPH).

RAM AIR

Operating Conditions
temperature = Tair = 20C = 293K
atm. pressure = Pair = 14.7PSIA
Cpair = 1005J/KgK
K = 1.4
the Cpair and K are constants for air.

Case 1 @ 100Kmh (62Mph) = 27.78m/s

Calculating temperature of the ram air

Tramair = ((Vcar^2/2gc)/cp) + Tair
Tramair = (((27.78m/s)^2/2(1kgm/Ns^2)/1005J/kg) + 293K
Tramair = 293.4K

the temperature increased by 0.4K or 0.4C.

Pram = Pair (Tram/Tair)^(k/(k-1))
Pram = 14.7PSIA (293.4K/293K)^(1.4/(1.4-1))
Pram = 14.75PSIA - 14.7PSIA
Pram = 0.05PSIG (gauge pressure)

so as you can see driving 100kmh will only have a gain of 0.05 psi! now lets try for 200kmh.

Case 2 @ 200Kmh (124Mph) = 55.5m/s

Calculating temperature of the ram air

Tramair = ((Vcar^2/2gc)/cp) + Tair
Tramair = (((55.5m/s)^2/2(1kgm/Ns^2)/1005J/kg) + 293K
Tramair = 294.5K

the temperature increased by 1.5K or 1.5C.

Pram = Pair (Tram/Tair)^(k/(k-1))
Pram = 14.7PSIA (294.5K/293K)^(1.4/(1.4-1))
Pram = 14.97PSIA - 14.7PSIA
Pram = 0.27PSIG (gauge pressure)

Norse396

This may be old, but I'll post it and let the viewers decide, if you think it works for you, great, if not, great.

Dispelling the Myth about "Ram Air" in Automobiles http://www.vetteguru.com/ramair/
There are many air intakes on the market today. Many claim "superior" performance over others.

Air intakes can be seperated into specific catagories:

- Those that take in warm engine bay air
- Those that are exposed to cooler/fresher air from the front.

The biggest bennefit of adding an aftermarket air intake is unshrouding the factory air box.

The last bennefit is exposing it to fresh air.

Ram Air is a myth, and many intake manufactures use the word Ram Air strictly for propaganda. They also try to show track results compared to other intakes that simply incur too many variables to make a meaningful and empirical determination. 60 foot times, atmospheric changes, shifting, etc, etc. So do not beleive anything you hear regarding such claims regarding air intakes.

Lets take a look at the "Ram Air" Myth in automobiles:

The Ram Air Myth by Dave Rodabaugh

The Ram Air Myth is the most mythical of them all. It differs from the other myths, in that the other myths are misinterpretations of physical phenomena, whereas ram air simply does not exist.

MYTH: Use of a scoop on the front of the vehicle to collect intake air, or provide “ram air” can raise engine performance.

TRUTH: At automobile velocities, there is no ram air effect.

SIMPLE EXPLANATION

The "Truth" statement says it all. How much simpler can it be? The Ram Air effect is a total myth because it simply does not exist. “But Pontiac uses it on the Trans Am, and they know more than you do.” To those who offer this, tsk tsk. Careful reading of Pontiac’s statements on the matter reveal that the HP increase of the WS6 package are a result of a less restrictive intake, and a freer-flowing exhaust, NOT any ram air effect.

So why does Pontiac use Ram Air? Easy! To make people buy their cars! And they are quite effective with this strategy.

DEEPER EXPLANATION

Of all of the applied sciences, fluid mechanics is among the most difficult for many people to comprehend. It is a relatively youthful applied science as well, meaning that it has not had two or three centuries of work to mature into an applied science on par, with say, chemical combustion. To make matters worse, it is mathematically defined almost entirely by experimentally-determined mathematics.

This last point is the true differentiator between those who only understand concepts, and those who can quantify what they are discussing. Truly, quantification is the real skill of the engineer. It is one thing to speak about qualitative issues (the “what” of the physical sciences); it is entirely another to quantify them (the “how much” and “to what extent” of the same). In grade school, students are first taught about “closed form mathematics” and then that these mathematics are typical of scientific expression. A good example of this is Newton’s famed “law of action and reaction”, the mathematical expression of which is a succinct F=MA. So straightforward. So simple. Three variables in perfectly-defined harmony. Given any two of them, the third is easy to nail down.

Unfortunately, a vast, vast majority of the mathematics used in engineering are NOT closed form. Instead, they are multi-variable correlations valid only for a narrow set of circumstances. Deviate from those narrow circumstances, and a new expression must be experimentally derived. Fluid mechanics is almost entirely defined by these experimentally-determined expressions, further muddying an applied science not well understood.

And if there ever were an applied science for which common sense is wholly inappropriate, it is fluid mechanics. Virtually nothing obeys the “common sense” rules of observation, explaining why those who believe in ram air have extreme difficulty in believing that is simply does not exist.

The Deeper Explanation begins with a basic explanation of engine principles. Air and fuel must be combusted at a specific ratio, namely, 14.7 parts air to 1 part fuel (this is a chemical ratio). Stuffing more fuel into the cylinders without increasing the amount of air they also swallow will get no gain whatsoever. So the hot rodder’s adage “more air = more power” is proven correct. Figure out a way to stuff more air into the cylinder at any given RPM and throttle setting, and you can burn more fuel. Since burning fuel is what makes power, more air truly does create more power.

The amount of air which is inducted into a cylinder is a function of the air’s density. As the air flows through the intake tract, it loses pressure, and as the pressure decreases, so does the air’s density. (Denisty is mass divided by volume. Since cylinders are a fixed volume, increasing the density will also increase the mass of the air in the cylinder.) There are two ways to increase the pressure and density of the air inducted into the cylinders:

- Decrease the pressure drop from the throttle plate to the cylinders

- Increase the starting pressure at the throttle plate.

Ram air is an attempt to do the second. Under normal circumstances, the air at the throttle plate is at atmospheric pressure, and this pressure drops until the air reaches the cylinders. Ram air would start the process at some pressure higher than atmospheric, and even though the drop is the same, the cylinder pressure is higher because of the increase at the start.

Just how would this increase in pressure at the throttle plate occur? The oft-wrong “common sense” says, “If a scoop is placed in the airstream flowing around the vehicle, the velocity of the air ‘rams’ the air into the scoop, thus increasing the pressure.”

Why is this incorrect? There are two types of pressure: static and dynamic. Placing of one’s hand in front of a fan, or out of a moving car’s window, clearly exerts a force on the hand as the air diverts its path to flow around it. Most people would say “See? This is a clear indication that ram air works. Clearly there is pressure from the velocity of the air.” Well, this is correct, but only to a point. This is an example of dynamic pressure, or the force any moving fluid exerts upon obstacles in its path as the gas is diverted around the obstacle.

What an engine needs is static pressure. This is the pressure the same fluid exerts on any vessel containing it at rest. For those who were physics/chemistry geeks, it is the pressure caused by the force of the molecules bouncing off of the walls of the container. The key to understanding the difference between static and dynamic pressure lies in the velocity of the gas. Dynamic pressure is only a momentum effect due to the bulk motion of the fluid around an obstacle. Static pressure is an intrinsic property of a gas or fluid just because the molecules of the fluid are moving around. Any fluid which is moving can have BOTH dynamic and static pressure, but a fluid at rest only has static pressure.

The point of ram air would be to increase the static pressure, which would correspond to an increase in the in-cylinder air density, and of course, more air. Superchargers and turbochargers do what the mythical ram air purports to do. A supercharger trades the power of the belt and uses it to compress the air in the intake tract. This energy trade-off results in an increase in intake air pressure, more air in the cylinders, more fuel burned, and more power. A turbocharger trades the power of the hot gases and uses it to compress the air in the intake. The overall effect is the same – an increase in intake static pressure.

For ram air to work, it would have to trade the energy of the air’s velocity (as the vehicle moves through the air) for an increase in static pressure (since static pressure is a part of a gas’s internal energy, we see this is TRULY a trade in kinetic energy for an increase in internal energy). Now for the true reasons why ram air is a myth:

- The way for air velocity to be traded for an increase in static pressure is to actually SLOW IT DOWN in a nozzle of some sort. This is easily the MOST counterintuitive part of fluid mechanics for most people. The “common sense” mind says “In order to increase the pressure of the intake, the velocity of the air needs to be increased, just as increasing the speed of a fan exerts more force upon the hand.” Not only does this confuse dynamic with static pressure, but is also misses the point, which is to trade the kinetic energy of the gas for an increase in internal energy. How can this trade occur if the kinetic energy of the gas is increased? It cannot, and in fact, the only way to trade it is to use the velocity of the gas to compress itself – by slowing it down.

- Below about Mach 0.5 (or about half the speed of sound), air is considered “incompressible”. That is, even if the correct nozzle is selected, and the air is slowed down (the official term is “stagnated”) there will be zero trade. No kinetic energy will be traded in as work capable of compressing the air. The reasons for this are not discussed here; the reader may consult any reputable fluid mechanics textbook for confirmation of this fact. In plain English, a car is just too slow for ram air to work.

Still not enough evidence? Here is a little test. For ram air to work, the nozzle must be of a specific shape. The “Holley Scoop” for the Fiero is the wrong shape, by the way. The fact that it has no net shape at all immediately means it cannot effect any kind of energy trade off, so it cannot possibly create ram air. This is also true for the hood scoops on the Pontiac Firebird WS6 package as well, by the way.

What shape must it be? There are two kinds of nozzles. Pick one:

- Converging. This nozzle gets smaller as the air flows through it. It has a smaller exit than entrance. If the nozzle were a cone, the fat end is where the air would enter, and the narrow end is where it would exit.

- Diverging. This nozzle is opposite the other; it gets bigger as the air flows through it. With a larger exit than entrance, the narrow end of the cone is where the air would enter, and the fat end is where it would exit.

So, which is it?

Without hesitation, most of the “common sense” crowd will answer “Converging.” BZZZZT! Thank you for playing anyway! We have some lovely parting gifts for you! Bill, tell ‘em what they’ve won….

The answer is “divergent”. Yes, the nozzle would have to shaped so that the skinny end is pointed into the air stream, and the fat end connects to the throttle plate. How can this be right? Remember, to increase the static pressure of the intake air (which is the true “ram air” effect), the kinetic energy of the air must be traded to compress the air. This is done by slowing the air down, or stagnating it, and the only way to do this is with a diverging nozzle. Ah, but since air is incompressible at automobile speeds, it doesn’t matter any way.

Conclusion

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.

- The “ram air” nozzles commonly employed on automobiles tend to be the wrong shape. A divergent nozzle is required for ram air. Straight-profile scoops cannot provide a ram air effect.

Select one of the two types of intakes, warm air, or cold air. Beyond that its just about looks.

Skeedatl

While oversimplified, the concept in that article is correct.

Swat Dude

Well, alrighty then, that just about sums it all up.

Norse396

Seems 1le has bought into GM's hype.

Skeedatl

WS6 ram air is domestic rice. Akin to a shopping cart wing on a Civic. All show...no go.

TLover

Wouldn't the power increase experienced in the motorcycle article HD cited to be linked cooler, therefore denser, air?

Norse396

It would be cooler than the intake picking up air near the engine, but it wouldn't be "Ram air".

TLover

Yeah, that was my point. It's cooler air not ram air. By the time the air makes it's way through the tubing and to the throttle plate, any pressure increase is lost, like Skeedatl said.

I have to laugh at that article. They measured the pressure difference at the inlet. Wouldn't one have to measure the difference at the throttle body?

Skeedatl

Depends on how the air is brought in. A lot of cycles have their intakes behind the forks, and like any mass, the airstream is directed around the bike just as it is a car so even though the intake is in "plain view" it won't necessarily draw in the coldest air. Only air trapped behind the forks.

In that case, "ram air" provides a steadier source of air, not compression. It's the same effect as if you were able to move the forks from in front of the intake.

Skeedatl

That is correct. In fluid mechanics, the vast majority of the study is figuring the effects on pressure and velocity of bends and diameter changes (those familiar with HVAC and irrigation systems run into these effects daily). The pressure at the inlet won't necessarily be the same as what is at the throttle plate, but the difference is typically so small that it doesn't matter. The difference is smaller than other measuring errors (a sig fig issue).


None of these 1LE articles have proper experimentation or analysis. They don't measure the effects that air box has on its own, they don't control the environment...they don't do anything. But that's typical of those who don't understand fluid mechanics and that these bends and different box shapes can (but not necessarily will) have a GREAT effect on airflow.