Wondering if anyone knows how to calc air pressure inside scoop at different speeds.
Formulas I have are unclear.
Any help appreciated.
Thanks all.

seems like it would be quite complicated- lots of variables to compromise the accuracy of the final calculation. wind speed, air density, vehicle speed, scoop opening area, boundary layer interference, leakage, engine intake volume versus vehicle speed/ engine rpm, etc. i'd stick some kind of barometer in the scoop. that would be interesting!

All I would do is put a pedo(sp) tube in and attach
it to a inch of water gauge to measure the pressure

Why in the world would you want to know that? I would think even if it weren't moving, if the carb is sealed to the scoop, it would still be equal the outside air.. As the cars speed increased, the pressure would increase. I'd imagine if the speed got so great, it would start building boost, as forced air is shot into the carb.

Barometric pressure is the force that is exerted on objects by the weight of the atmosphere above them. A screw weighs the same under the scoop as it does out of the scoop, so the air would weigh the same, just the force of accelleration would increase it's density.

about 15 yrs ago in national dragster the tech section covered prostock and the pressure/hp gain from it.about 1.5% gain in hp if i recall.at the track i have seen 1 person with a large dial psi guage reading from 1 to 6 and i believe he was getting 2psi but it couls have been more.

I just wrote a hugmungus tech reply and lost it by hitting somthing wrong

put a -10/0/+10" water magnahelic in ,do run record data,drink talk bench race,
do mods repeat as necessary till you run out then

Scott, this is the best that I could find. I guess when you are at that level of racing, this stuff makes a difference..
Very good read. I read it twice.
http://findarticles.com/p/articles/mi_qa4078/is_200306/ai_n9240601/

The formula for theoretical maximum ram pressure ('velocity head') is:
p = pv²/288g, where
p is the velocity head in psi
Þ is air density in lb./cu. ft.
v is velocity in ft/sec. (88 ft./sec. = 60 mph)
g is acceleration due to gravity, 32.2 ft./sec/sec. on our home planet

So for example, at 150 mph (220 ft./sec.):
p = (0.076 x 220²)/(288 x 32.2) = 0.4 psi (~11 " H2O), or about a 2.7% potential power increase.

When measuring scoop pressure a big problem is that we are looking for a pressure difference between the inside of the scoop and the atmosphere, but in a moving car, where can you measure undisturbed atmosphere? Opening/closing windows affects a gauge with it's reference pressure pick up in the cockpit, as does flow through any openings in the firewall, rear of the body, etc. The answer is a static pressure tube (one half of the pitot/static probe used for air speed indicators on aircraft)

The additional air being sent into the carbs in a typical scoop like yours at 150mph is .40 psi at 180 its .53psi
and at 210 about .65 psi.
which means that 14.7psi + .6 psi +15.3psI or 15.35/14.7=1.044psi or 14% more Air introduced to the carb tops at speed vs non ram air effects.
this is all assumind sea level and all other things being constant.
i can also work it out in ref to inches of HG like the DA readings give you in feet.
thats why you run better at a lover elevation where the air is heavier thus denser, more air 20/80 gets to mix more fuel into the same cylinders.

I didn't see any mention of Bernulis (SP?) principle on fluid dynamics and the venturi effect of the hood scoop opening if it is acting as a venturi In a venturi the pressure decreases as the air speed increases

Thanks all for the replies, excellent info.
Just thinking about two issues been rearing head recently.
1) scoop potential
2) pressure increase in entire engine bay, fender to fender.

Have resolved these issues prior, contemplating new ways to solve them.

Need to find supplier of pitot tubes, static pressure tubes gauges and related equipment.
Any recomendations Greg?

As the speed of vehicle is increasing, realizing were loosing significant amount to parasitic drag and other entities.
Thinking additional improvements in air management will reap sizable gains.

See the cover of ND, Jim Defranks car?
Hmmm, need some wind tunnel time or smooze with some Bonneville guys.

Thanks Greg.

I am impressed with the amount of info available thru the links on that page.
All those Nasa links amongst the others... Geesh one could get a degree online.
You guys digest all of that info in a semester?