Hmmm...Dave Rodabaugh seems like a smart guy but there appeared to be a few flaws in his reasoning. I'm not sure where he learned his lessons on static pressure but it is obvious he is not a physics major. I work for York International,( they design and build air handlers, centrifugal chillers, screw chillers, recip. compressors, and VAV systems). Millions of dollars have gone into R&D and i have yet to see Dave's philosophy used on any of our systems. Basically York uses a "converging" type of system on all buildings to regulate static pressure AND velocity. I'm sure if a "diverging" system was more efficient York would employ such an idea.
I am not claiming to be a physics major...I just know what happens in the real world in real situations. His theory is interesting and warrants merit but I would not consider it gospel. As for the "ram air" effect I'm sure a very "slight" pressure may be created from Pontiac's hood, but it is probably so small that only extremely expensive and sensitive equipment can measure it.
Just my 2 cents...
P.S. - remember jets fly at high altitudes so you can't compare jet engines with automobiles engines. Less air and atmospheric pressure exists at those altitudes...to do that would be comparing apples to oranges.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Mach Go:
<strong>
P.S. - remember jets fly at high altitudes so you can't compare jet engines with automobiles engines. Less air and atmospheric pressure exists at those altitudes...to do that would be comparing apples to oranges. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, some of the faster jets in the world also fly very fast at low altitude, as in 50 to 100 feet above the ground, as well as at high altitude. Been there, done that; low is more fun.There are a bunch of folks in Iraq doing just that recently. Sometimes too much ram air into the engine is a jet's biggest engine problem.

We're really not comparing turbine engines to recips here, just how air acts. Of course, the air doesn't know or care what kind of engine it's feeding; it just acts like air. Controlling it is lots easier than trying to herd cats; air is predictable.

 

Engineers and politicians love to hear theirselfs talk (or type). Like the man said... I put it on my car and it ran faster... That's good enough for me. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

I don't think pontiac's intention was to fool anyone about the hoods function.
They called it RAM AIR, so what! They could have called it GREAT AIR, or even CHIMPS ***.
My point is they gave there hoodscoop a name exclusive with the pontiac brand!!
It is obvious what the hood is designed to do! Get over it.

 

Call it what you will. These so-called "RAM AIR" kits make track proven improvements. Nice research by these guys though. I have learned much from these readings oh wise ones. It is good to know that there are people out there saving us from the <img border="0" alt="[bullshit]" title="" src="graemlins/gr_bs.gif" /> ers.
Thanks.

 

I am a little late to this discussion but I would like to throw in my 2 cents worth. My credential: I am an aerodynamic engineer (B.S.,M.S.,P.E.) with one of the big 3 and I work stricly on motorsports R&D. I have tested ram air on many vehicles and I can tell you it is no myth. And it works because of total pressure which is static pressure plus dynamic pressure. Our testing does show though that many factors contribute to its effectiveness and every vehicle has what we call a "cross-over" speed where ram-air starts increasing engine power. Cold air though is always a good thing and will help performance at almost any speed.

 

Well, Webster tells me that Ram means:
1.to strike with violence
2.to move with extreme rapidity
3.to force passage or acceptance of

I'ld say the holes in my hood help to do all of the above to "air" - I'm satisfied with what they call it.

What I'm wondering is why those of us who bought the "Ram Air" and paid the money for it aren't the ones complaining about what they call it and that it is false advertising! Hmmm <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Motown Blue:
<strong> I am a little late to this discussion but I would like to throw in my 2 cents worth. My credential: I am an aerodynamic engineer (B.S.,M.S.,P.E.) with one of the big 3 and I work stricly on motorsports R&D. I have tested ram air on many vehicles and I can tell you it is no myth. And it works because of total pressure which is static pressure plus dynamic pressure. Our testing does show though that many factors contribute to its effectiveness and every vehicle has what we call a "cross-over" speed where ram-air starts increasing engine power. Cold air though is always a good thing and will help performance at almost any speed. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Whats the crossover for T/A's. I think the general rule of thumb is 60mph correct?

I am suprised nobody has quoted more track times. From my understanding removing the baffels improves E.T's around .1-.2's. I think there is also a kit to help seal up the air box to the hood and remove the grill on the nostrils of the T/A ram air.

Hell I am going to get a WS6 if not buy the hood just cause it looks freaking mean!! But I am feel also pretty confident I would see some improvements at the track because of cooler air entering the intake track. <img border="0" alt="[driving]" title="" src="graemlins/gr_driving3.gif" />

 

I think some of you guys are missing the point of the debate. There is no doubt that suppling the engine with more cold, outside air (ie. SLP CIA, FTRA, SSRA, BG RA, Baffle Removing, etc.), as opposed to having it take in hotter air from the engine compartment, will net 1/4 proven gains. The question is: Is it the air being theortically "rammed in" that's causing the gain or the fact that you are just supplying more cold air to the engine (which we KNOW is the reason for MOST of the gain)?

<small>[ April 18, 2003, 12:35 AM: Message edited by: 2000LS1 ]</small>

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by last of the Z28's:
<strong> so then just remove your air deflector on the bottom of your car and replace it with a custom fiberglass scoop about 3"s high the full length of the deflector.(now for the hard part) the exit for the scope make a outlet of lets say 2"h by 8" wide. then before you hit your air box increase the ducting to as big as you can go to the air box.
now you have a large area of collection. the smaller size output to the larger final duct size now acts like a diverter. done! that was easy enough huh? oh ya.....get off the pipe man! </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep, just like the Pro Stock and F1 guys do. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

I think its both

1. Cooler air temps
2. improved volumetric efficiency

IMHO I think that the functional "ram air" helps improve the volumetric efficiency at higher speeds because it does produce a stagnant high pressure area directly in front of the notril. I don't think its compressing the air, the speeds are to low for that.

I believe the author of the article was speaking in terms of compressable air instead of non-compressable fluid which should be the assumption for the speeds of our cars.

The concepts he states are valid for high speed, not low speed. His arguement do not apply to our cars.

to <img border="0" alt="[boring]" title="" src="graemlins/gr_zzz.gif" /> to pick apart his arguement and reread all the posts...................

 

Ram air does raise the pressure at the point of intake by adding the dynamic pressure (q, which is a function of velocity squared) to the ambient static pressure. This additional pressure is theoretically there at any speed over 0 mph. It just doesn't show up as horsepower because it is small at low speeds. For instance, at 100 mph q is only 0.17 psi which would bring your total pressure up from say 14.70 psia to 14.87 psia. Whereas, at 200 mph q is 0.67 psi giving you an intake pressure of 15.37 psia. This increase will start getting you some serious horsepower.

 

Okay, the original statement or post kept refering to fluid dynamics or mechnaics. But I know boats and other sea vessels deal with hydrodynamics and cars and planes deal with aerodynamics. So if the two have different terms, do they have different equations or variables? Does air act like fluid? Should he even be bringing up fluid for an argument about air flow? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
All I know is that my motor is a happy camper! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Dean <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />

 

Good info Motown

Even though the pressure increase is small, its still there and does have an affect on the overall performance on the 1/4 even if its just small.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by db99sscam:
<strong> Okay, the original statement or post kept refering to fluid dynamics or mechnaics. But I know boats and other sea vessels deal with hydrodynamics and cars and planes deal with aerodynamics. So if the two have different terms, do they have different equations or variables? Does air act like fluid? Should he even be bringing up fluid for an argument about air flow? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
All I know is that my motor is a happy camper! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Dean <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes air, like other gasses is a fluid, a compressible fluid.

Water, oil and other liquids are incompressible fluids. Falling out of an airplane doesn't hurt much when you hit the compressible air (unless you are going REALLY fast), but when you hit the incompressible ocean at the same velocity....ouch!

There is a big difference, and some of the formulas are either different or have compressibility factors in them.

Mixing liquids and gasses can cause problems, like air in your brake lines or in your bloodstream. Both are a short trip to disaster.
The whole topic is still called fluid mechanics or fluid dynamics. The other type is mechanics and dynamics of solids, or at least materials in their solid state. Water can be either a solid, liquid or gas depending on temperature and pressure.

Bonus question: can water exist as a solid, a liquid and a gas at the same time in the same container?

 

Being a mechanical engineer, I have thought through these ideas much myself and have pondered the affectiveness of the ram air system from a pressure standpoint.

I have a few points to keep in mind.
The velocity of a fluid over the surface at the surface is zero and increases to the free flow velocity as you get farther from the surface. So What is the velocity of the air near the center of the nostril?

Secondly, as you are driving, and air splits to go both over and under the car, there is some point in which the velocity is zero (aka stagnation point) and I would think that may be somewhere near the intake of the hood. Obviously you can't really tell from just looking at the car.

I think there are too many variables to consider to argue here, and testing may be the best way to determine the true effectiveness of the "ram air" system.

Overall, like others, I believe the true benefit of the "ram air" system is the cooler air temps entering the engine. This may be why systems like FTRA and others may work better being sealed...rather than sealing in the pressure, it seals out the hot under hood air from entering the engine.

 

2000LS1, come on dude 288 posts and 20 pages at Anythingcars is enough! We settled this debate already. <img border="0" title="" alt="[Razz]" src="gr_images/icons/tongue.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by db99sscam:
<strong>Does air act like fluid?
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Ackattack:
<strong>velocity of a fluid over the surface at the surface is zero and increases to the free flow velocity as you get farther from the surface. So What is the velocity of the air near the center of the nostril?

Secondly, as you are driving, and air splits to go both over and under the car, there is some point in which the velocity is zero (aka stagnation point) and I would think that may be somewhere near the intake of the hood. Obviously you can't really tell from just looking at the car.

I think there are too many variables to consider to argue here, and testing may be the best way to determine the true effectiveness of the "ram air" system.

Overall, like others, I believe the true benefit of the "ram air" system is the cooler air temps entering the engine. This may be why systems like FTRA and others may work better being sealed...rather than sealing in the pressure, it seals out the hot under hood air from entering the engine. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">1st point: Doesn't really matter, those rules apply to laminar flow, there is going to be turbulent flow as it goes through the "ram air".

Leads to your third point of emperical data. When dealing with turbulent flow, really the only way of knowing is to do just that.......test.

I agree with your conclusion as well.

 

Couldn't pass this up. My .02 cents. I've been really looking at this as I'm building a LS1 hybrid. What I've found: I know air does not have much mass but in fact a cubic foot of air weighs about .076 pound. We can use this mass to increase pressure (and therefore density) to the engine. However when the math is done using 0.076lb/cu ft air density and a vehicle speed of 100MPH you would get an increase of 0.18psi above the 14.7 atmospheric pressure which is barely a 1 percent increase. And that is not taking into account any losses due to any turns or bends in the ram air ducting, slight friction losses, nor intake shape/size and recoverable ram air effect (insert the physics here about con/divergent. Or simpler stated the fraction of that (ram air) energy that can be recovered.) Of course when you doing a 180MPH you get almost .5psi which is good for almost 3 percent. That's it! If ram air ain't working for ya, your too slow. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />