Franc, Are you going for you or for Shark067? Who is going to be buying this mystical AeroBlue you speak of?

 

There is a gauge on my car that says "vacuum" I wonder what it means?!?

Speaking scientificaly, Vacuum is the abscence of matter. Partial vacuum is the differential between the gases in two containers. Partial vacuum is the "vacuum" of which we are speaking and is generaly expressed as simply vacuum in engineering, not scientific circles.

We draw a "vacuum" of 20 Inches of Mercury on a package of Hot dogs. In the grocer's case there is no vacuum in the package.
We draw a "vacuum" of 12 inches on a can of Coffee. When you open it you will hear a rush. That is because, unlike the soft film surrounding the hot dogs, the hard can maintains the "vacuum" from the packaging process.
We draw 15 inches on the products we package in unsupported films. It creates the same adherance of the film to the paper much like the metalizing of plastic or in your example, the mirror. However the mirror and the film are softened by heat and the aluminium particales then actually adhere to the film or the glass. One of our products "Thermolock" does that (for packaging inside with the Hot dogs). But for the most part, the film adheres to the paper coupon by the ambient air pressure on the outside of the package.

Just like it does in a package of hot dogs. Only the package of hot dogs is drawn while stopped in a "Vacuum chamber" One of my patents does it in motion without using a closed chamber.

Like I said, I do this all day.

I can read WIKI also. Next time you want to pick the fine point post the whole WIKI explanation.
Vacuum - Wikipedia, the free encyclopedia

And for the record, the legal definiton of my related patent says "vacuum."

 

Time to bait the hook again.

You, and anybody, could soon own this lovely example of Eric Stoddards pen.

It will be for sale, sorta.
Keep a peeled eye on the CAA threads.


roadster with a stick

 

Pitot tubes measure velocity.

 

Yes they do. But engineers, and crazy racers, innovate. I'm not dancing around with you on this one.

Except to ask, do you know how a pitot tube operates?


Exerpt From WIKI
The dynamic pressure is then determined using a diaphragm inside an enclosed container. If the air on one side of the diaphragm is at the static pressure, and the other at the stagnation pressure, then the deflection of the diaphragm is proportional to the dynamic pressure, which can then be used to determine the indicated airspeed of the aircraft


The important word here is "dynamic."
roadster with a stick

 

THis thread has elicited many thoughtful answers and even more explanations, well done.

Humans measure things in proportion to themselves. Its bigger or smaller than except for alice in wonderland who has no sense of proportion, anyway.

Many people think that heat pumps dont work below 0 F. because there is no heat. Zero is actually -470 degrees or so below that, durn I should remember the correct number. Make personal note to learn it.........

We are immersed in the atmosphere so there is no pressure and more is pressure, less is vacuum. Right???

Well not really. Iam gonna get a GOOD gauge to monitor the pressure increase on the front of my car versus the static inside it. It is digital and should be of interest to this group.

Glad we have a thinking issue now and then to keep the cobwebs to a minimum. ENJOY W DY

 

True words Woody. I will be running tubing from the front of the car to the cabin. The cabin should give me ambient or close to ambient air pressure. This will be my "stagnant" value. I will measure in front of the grill and behind the grill to see any differencial.

I will not likely be able to tell how many Lbs or inches of water the ram pressure will provide the TB but I will be able to prove that ram air has dynamic pressure and whether it is a different value in front of the grill than behind.

One note on the grill popping out. It is likely that the airflow over the grill caused the lower pressure in front. Seems counter intuitive but possible.

Gonna try my "Myth Busters" episode this coming weekend.

Querry?
What is a good way to get tubing inside the cabin without opening a window?


roadster with a stick

 

-273.15*C
-459.67*F

...absolute zero...

 

Firewall feedthrough behind the battery.

 

Thanks.
Is that the small opening where the wire bundles come thru on the passenger foot rest upper right, just under the gove box?

Seems a lot of work to get there from the engine side. But, if I could feed it thru from the passenger side that might not be too much work.


franc

 

is this the same explanation for cold air.is that diff or the same as cold air?

 

That your HEPA filter needs change ?

He [onehundred80] apparently doesn't understand internal combustion engines...

 

I dunno, but I do know that THIS guy is definitely getting some RAM EFFECT:

 

Kell and I will be going to Texas this Thursday. We will be doing the myth busters thing. I have an inH2o meter for 0 to 15 inches. we will have a pitot system from the front of the grill, the back of th grill out the window witha 1.0" collector horn and a 3.0" collector horn.

I have divised a method of calibrating the stagnation air in the cabin when we open the window. While we cannot develope significant data to use to engineer ram air systems, we will be able to prove, with some certainty, the following.

That air pressure in front of the grill is different than in front of the radiator.

That ram air developes pressure at specific speeds

That the collector horn size effect the pressure at the meter suggesting the ability to "compress" the air,,(not just increase it's velocity) by progresively reducing the size of the collector tubing.

Finally, we hope to prove tubulence created by curves and elbows in the intake system will effect tail pressure ( the pressure at the TB).

Somebody has already proven this stuff somewhere I am sure but.
It will be a blast doing the Myth Busters thing and putting the presented Technical Editorial under our boot.

Or Not.


roadster with a stick

For the record, the guy designing the test is a fluidic expert. Before working for me he designed and built test equipment for medical apparatii that used very precise fluidics to deliver medications. His grasp of vacuum and pressure systems far exceeds mine. And he holds or developed 11 patents in the science.

Just sayin'

 

There is something in that pic that should be rammed, but it sure isn't that stack

 

I would offer to provide a mythbusters test. I already have the apparatus in hand, so to speak.

But I suspect Crumpy would object.

roadster with a stick

 

Franc:
Since you are testing STATIC pressure there is no flow in the pipe and therefore no pressure losses or flow issues. I have used the 1/8" nylon air shock kind of 'hose';( oil pressure line for cheap gauges) and run it in the passenger door without it being pinched by the door gasket.

I measured the 185 pulley on my car and found 30 INCHES of water column vacuum at the throttle body of the Needswings CAI 3" intake, and published my findings on here. That was 1 psig or so drop in a single pipe, thus my design of the dual intake, AS A RESULT OF MEASURMENT [ at 6000 rpm].


That netted me 35 HP on the dyno, same day within 10 minutes by simply removing a plastic bag off the second air filter. Remember this was BELOW 3000 RPM< a HUGE gain that has to be experienced to be enjoyed ( 7 hp on the top end).

ENJOY<< Woody

 

The way I see it, all the air would be at 14.6 psia but the velocity of the air would be higher. The only way the pressure would increase would be if something closed the system, and pushed the air forward while the other end was blocked. The air is not going to be compressed, there is no nozzle effect as the diameter of the pipe is constant, but the oxygen molecules will be there when you need them (intake stroke). In a carburated car, where air is drawn through the grille, through the radiator and into the air filter... It makes alot more sense to draw the air through the hood to keep temperatures low and velocities high. In a fuel injected car, the stock airbox is designed in the spirit of "ram air", in the form of a remote inlet.

 

If you put a 3.0" elbow pipe out the window and pipe in about 2 feet of 3.0" PVC tubing you get air to flow thru the pipe. Agreed?
If you cap off the end with a smaller hole in the cap, you will get air to flow thru the hole. Right?

The only reason air would pass thru that hole is because it has a higher pressure than the air in the cabin. The assumpton can be made that the air in the tubing is under pressure. Otherwise the air in the tubing has no reason to pass thru the hole.
It can also be assumed the continuios the ram effect will maintain that increased pressure.

So long as the volume of air collected is greater than the volume of air consumed, the intake should have positive pressure. This is a function of the size of the collector orfice.

So now you have more air coming into the TB with increased pressure. Is that not how mechanical compression systems work?

roadster with a stick

 

I'm almost positive that a boost gauge on a naturally aspirated car's intake tube would read 0 psi (maybe a fractional increase, but nothing worth looking at) no matter how it is positioned. As you mentioned, there is a vacuum inside the engine, which as you said is a giant air pump... that's the only real pressure difference. If you held a pipe with a ballon duct taped to one end out the window, it would not fill up the balloon.. The air would occupy the balloon until the point that it needs to be compressed, then "new air" would flow around the contraption.. The pipe might fly out of your hand because the air is at a higher velocity relative to the pipe. Having a large pipe with a small hole on the end is a nozzle.. that's a different story than ram air. Air will not compress itself.