NZConvertible

Forget that stupid diagram. The fact that there’s no title, explanation, legend or units means it probably came from the marketing department (for a brochure) rather than the engineering department!
The front of the car is always going to be a high-pressure area, as is the base of the windscreen. It just makes sense. As someone wise said here the other day, “think like an air molecule”, and picture what would happen as air hits the front of the car and tries to follow its lines. You can also see the lines pointing away from the surface of the car at the back, which is a known low-pressure area.
Another explanation for that diagram is that they’re force vectors. This makes even more sense if you think of the effect pressure has on a surface. By definition it exerts a force on an area.

rx_7_driver

the hood scoop does work cause i have one and everyweek when i clean out the engine bay i have to get in there with a tooth brush a scrub the damn bugs of the intake manifold that got burned on there

RotaryMiata

Can't argue with that logic!!!


RM

bingoboy

that air is tryin to lift the car, pressure would be there even if there was no hole. thats what front spoilers are for, to take advantage of that air pressure. also..the radiator hole is put there to take advantage of that pressure against the car, it doesnt actually make the air pressure itself.

if there was a hole in the middle of the hood(with the arrows pointing out at that spot indicating negative pressure at that point) air would flow OUT of the hole (though without a profile showing the effect of the bulge scoop from a TII hood we can't tell how that would affect air pressure, but it obviously works for them). the air on the top of the car is at a negative pressure because the front of the car is pushing air up and away, thus the air is pulling the hood up.

also see that air slamming into the base of the windshield/hood area? thats why cowl induction works. its all very simple, it just requires you to look at it in a way that is backwards from common sense logic

ponykiller

Everything is backwards from common sense. errrrrr....


Kris

Maxthe7man

Not sure what you guys are really trying to prove here, but I drove with temperature probes in the hood scoop on a 70 degree day, the probes read 130-160 degrees until I hit 45 mph then they read ambient, which means that no air does not flow through the hood scoop unit speed reaches 45 mph plus, below that hot air was actually coming out of the hood scoop..Max

ponykiller

What if I was to mold a new insert for the hoodscoop that was about 1 inch taller; therefore, it would be up higher from the car, where very little air moves, or so I am told. Is this plausible?

Max-good info, but once you were over 45mph, did the temp drop to ambient, or was it still a few degrees higher?

Kris

NZConvertible

That's exactly what I would have expected. At low speeds when there is little airflow through the scoop, the easiest way for the hot air in the engine bay to escape is up through the intercooler (hot air rises remember), with the scoop acting like a chimney, turning the IC into an intake air heater!

Maxthe7man

Yeah around 45 mph it started to read ambient..
Once I lifted the hood and checked the intercooler temps after cruising around under 45mph, I had not been on boost at all, and the intercooler temp was still 140 deg.. I think the intercooler was more cosmetic than actually functional, I am going to go front mount with my new t04...Max

ponykiller

That makes perfect sense.

If a scoop was made that had an inch taller opening, would that draw air in at a lower speed and improve the IC's efficiency?

Just wondering....

Maxthe7man

Something like the Mopar hemi scoop thats about 4-5 inches tall would probably work, but the car would look pretty strange..Max

Gene

iTrader: (1)

low pressure along a surface = high air speed. That's why airplanes fly and why NACA ducts work. The T2 scoop does work, I found a dead hornet smooshed right smack square on my IC once. Working doesn't stop it from sucking **** however, thanks to heat soak when stopped (and moving even, since it's on top of a hot rotary) and insufficient core size (esp at above stock boost)

ponykiller

How about painting/coating the bottom of the IC with some insulation (ie. paint). Would that help to ward off the rising heat from penetrating the IC?

Kris

RevinRx7

iTrader: (3)

Ok i have a couple of ?'s.

- First , what are the negative effects of a frount mount intercooler? I mean isn't heat soak a bad thing? doesn't a front mount get rid of that?

-Second, I wonder if there is a way to make a cage on top of the IC so it could hold like a bag of ice or something. or just put ice on it. cause i know thats what some people do on high performance porsche's.

Gene

iTrader: (1)

ice would work for dragging and autox, but not for circuit and street. Downside of FMIC is longer pipes for more lag, and it can restrict airflow to the radiator. It can also compromise front crash resistance...

bingoboy

wonder if a small E-fan could me mounted to suck air through the ic somehow

RevinRx7

iTrader: (3)

Why wouldn't ice work for the street. i mean that sounds rediculous. if it works for one it should work for all. shouldn't it? Just put some on if you know you are gonna go cruising.
- As for a front mount having more lag, sure but you are getting cooler air which helps when the boost kicks in.

RevinRx7

iTrader: (3)

if you are worried about that much heat just use a water misting system. Or just use an extremely small amount of Nitrous Oxide, that should cool the intake temp real fast.

- One more thing. Why would a frount mount compromise crash resistance on a car that never had a front mount to begin with? its not like you are taking stuff away from the front end. Remember, this is no Shitsubishi Lancer who can't pass crash tests with a front mount.

Relisys190

iTrader: (4)

how how about this. (I'm sorry but i'm stuck on this raised hood thing)

Since the area right below the windscreen is a pressure area. (air goes in) If you raise the leading edge of the hood about an inch and removed the rubber strip that normally runs along the hood would air enter thru this? It would be a cowl induction hood. It would probably vent heat under 25-30 MPH. and than air SHOULD enter ... after 30-45. am i correct? that's just the way i see it.

-Markus

SureShot

In summary:
The chart shows pressure "at the surface". It is not a flow diagram.
It's which way air would flow if a hole were drilled in the surface.
As soon as you get above the surface with a scoop, that chart does not apply, which is ponykiller's point.
The modified chart is probably a little conservative, but the principle is correct..

Fingers

ponykiller, your logic is incorrect. The reason why there's a low pressure area where the hood scoop is is because air gets pushed out of the way by the bumper. It in turn creates a layer of air that's been raised off the surface of the hood. THAT is why the hood scoop is placed in a bad location. Now if the hood scoop was reversed, it would be better, but there still would be a problem due to the fact that now the air must do a 180* turn to get back into the hood scoop.