Also, look up velocity pressure or dynamic pressure, since that is the physical phenomenon that comes into play in this situation. You will see, that for relatively low velocities, (less than 0.3M above) the equations converge for compressible and incompressible flow. So you could use the equation:

q = 1/2 pv*2

to calculate the pressure gain.

You've drawn the wrong conclusion. Go look up how a pitot tube works and you'll see that there is something called dynamic pressure. A hood scoop creates dynamic pressure at any speed. There is nothing magic about 230 mph. An Indy car creates down force well before 230 mph. Small airplanes fly at speeds lower than 230 mph.

Well, nothing else seemed to be working.

And you asked for opinions, 3 or 4 times I have already given reasons contrary to your thinking, among others who have also, and you keep making statements with out any backup, and now are using charts referencing aircraft design considerations, which have little bearing on this forum or topic, and you continue to ignore those concerns voiced by many, and in deference to feets, they have yet gotten to the point of simply call a spade a spade, or as I succinctly stated, "BS", which seems still pretty accurate.

"Feets" taking a shot at me about my comments here. when you have me on "ignore", bizarre

Somebody Quote me please

Best of Moparts?

And people wonder why we can't get a good government in place.

Stir the pot. You hit it there buddy.

I think it clearly explains that the is a marginal PSI increase up to 14.7psi. .25psi .30psi whatever. Now that example of a 17hp increase was was an example for 200hp engine. On a 1000hp engine it would be around 85 hp increase from a .25psi gain. Obviously it doesn't take the cooler air into consideration because it'll be more yet. No BOOST yet. From what I read, you'll make BOOST after 230mph from ram air. 15.5psi, 15.7psi 16psi. In other words 1psi above atmospheric pressure increase per xxmph above 230. K? K.

Why are you so hung up on 230 mph? The air molecules don't know how fast the hood scoop is going. It isn't like they look at a car and say "it is only going 210 mph so we're not jumping in".

The pressure in a hood scoop will increase with the square of the velocity starting from zero. It isn't a light switch that turns on at 230 mph. There will be positive pressure (greater than 14.7 psi) at any speed above zero. The equation was posted back on page one of this thread.

When you can back up your claims, with actual TRACK TIMES, instead of just "theory", then report back. K?

Why did IE go from "The "myth" of ram air.. does it WORK in cars/trucks?" to "boost"?

Ram air works, even if it does nothing more than allow the engine to get cooler air. I suspect that was the intent of most air grabber type systems.

Well it's just the fluid dynamics theory. That's all. Show me the contrary proof that ram air can give positive pressure. Again, great conversation (some notable exceptions however).

Where is that dead horse thingy?

Just being honest here, "Idiocracy meets Moparts" thread

This has been a fun waste of time.

Show me the contrary proof that ram air can give positive pressure

As I said in an earlier post:
Depending on scoop inlet area, as soon as the vehicle sees a specific velocity that creates a flow volume greater than the engines need at its specific RPM you will, from that point and accelerating further, have a positive pressure situation.

This theory you have with those graphs are for clean flow situations like air passing over an aircrafts wing. They have no bearing here.
Now for the above:
Lets take an engine with an air consumption rate of 1000cfm.
Now the vehicle has a scoop with an inlet area of 30in^ or .21ft^
We know Q=VA, where Q is volume fluid flow in this case in CFM.
V= the vehicle velocity.
A= the area of the scoop.
Simple algebra V=Q/A
1000/.21=4761.9 FT/Min or 54.1MPH
At that velocity and above pressure will start to increase. More air entering than the engine normally consumes so the unused air compresses and builds pressure within the scoop. How much is hard to calculate as there are turbulence issues in the scoop. We actually had a scoop on the Comp car that created enough reversion above the carb that it sucked fuel out of the vent tubes at a certain speed. Took a while to figure that one out. I am now out on this subject.

so the RAMCHARGERS were correct all along!!!!

That has been done several times on this thread. You seem to have your brain locked on something and won't let it go.

Positive is defined as an increase.

If a container has 12 inches of vacuum and you raise the pressure to 3 inches of vacuum that is considered a positive increase in pressure. While still a vacuum, the pressure is higher than before.

You seem to be the only one fixated with pressures above barometric.







Sadly, the primary exception seems to be the OP.

That can't work. It's way too obvious and simple of an answer!

You don't understand fluid dynamics. You read a Wiki article and didn't understand it and now it appears that your brain has locked up. If you understood fluid dynamics then you would understand the concept of dynamic pressure and how to calculate it. You would look at how a pitot tube works and you would understand that it is the same principle as a hood scoop. If you had any sense at all you would type a few search terms into Google and come up with stuff like this thread:

http://www.yellowbullet.com/forum/showthread.php?t=366312

I've been in cars with no hood, and no air cleaner, and fuel getting sucked from the carb, onto the windshield...

I also assume all racecars with brake cooling ducts are just for looks, as air can't possibly be rammed in and be affective....

Here is the graph of dynamic pressure relative to speed. A well design air scoop should be able to capture most of this pressure. I think this chart comes from Moparts member Mark W.

I spent some time talking to a guy that raced 68 W31's (ramrod 350) for Oldsmobile. The 68 cars used two ducts routed to scoops under the front bumper. He did a good bit of testing and reported that this was worth significant ET and MPH improvement. He did mention that the scoop-under the bumper design on the 68 cars where more effective than the sealed hood scoop design used on the 70 cars.

Also, aside from any increased intake pressure effect, we know a cooler intake charge is beneficial.