Streetrod

Guys and girls,
I searched for this answer first but could not find anything close. I thought that the Naca Duct on the front brought in cold air?
Upon installing my HallTech I took a good look and can not see light through it. Do you have any information on how much air leaks through or the heat in the cavity from where the KB gets it's air? I was under the impression that there wasn't a need for ducted air? Am I wrong?

StreetRod

Bumpstick

I swiped this from another forum.

Quote:
Originally Posted by ZO6isthebestever
Why is it that the hood scoop isnt functional. They should of made it functional could help out in the air intake maybe could be a forced air intake. hmmmm Im thinking here


It is functional. Cold air is directed downward through the duct to the top of the AIS and is brought into the intake from the bottom of the entrance to avoid turbulence.

All other methods of bringing cold air into the airbox creates airflow vector disturbance, which causes surging under very low throttle positions.

Local thread.
http://forums.corvetteforum.com/show....php?t=1704442

Do a search using NACA



Watch the vidio link.

UTVOL06

If you open your hood and look through the NACA duct you can see your air intake. After installing the killer bee intake I could see the blue filter through the duct. Air comes in and shoots downward.

Streetrod

Thanks!
Exactly what I wanted to know.

SR

tigertank

uh what is a naca duct?

LTC Z06

It's in the FAQ, written up by Jim Hall on how and why the NACA duct is the way it is and what it does.

LTC Z06

The NACA duct or NACA scoop is a common form of low-drag intake design, originally developed by the National Advisory Committee for Aeronautics (the precursor to NASA) in 1945. When properly implemented, it allows air to be drawn into an internal duct, often for cooling purposes, with a minimal disturbance to the flow. The design was originally called a "submerged inlet," since it consists of a shallow ramp with curved walls recessed into the exposed surface of a streamlined body, such as an aircraft. It is especially favored in racing car design.

Prior submerged inlet experiments showed poor pressure recovery due to the slow-moving boundary layer entering the intake. This design is believed to work because the combination of the gentle ramp angle and the curvature profile of the walls creates counter-rotating vortices which deflect the boundary layer away from the intake and draws in the faster moving air, while avoiding the form drag and flow separation that can occur with protruding inlet designs. This type of flush inlet generally cannot achieve the larger ram pressures and flow volumes of an external design, and so is rarely used for the jet engine intake application for which it was originally designed, (the North American YF-93 and Short Sherpa being exceptions.) It is, however, common for engine and ventilation intakes.

http://en.wikipedia.org/wiki/NACA_duct

tigertank

ok where is the naca vent under the car?

LTC Z06

The NACA style duct is on the nose of the car.

American Power

"All other methods of bringing cold air into the airbox creates airflow vector disturbance, which causes surging under very low throttle positions."

I have a Vararam intake and have no surging whatsoever.
If I pull off to the side of the road and put my hand on the throttle body it's ice cold. Plus, it works!
GM should have made that scoop function like Ram Air.

These other explanations are Jibberish at best.

LTC Z06

And "Ram air" isn't jibberish? Porsche claims 10 hp with their ram air system at 186 mph.

Halltech

tigertank

thx jim and maj thats good info i always wondered why the hose intake didnt work hey where can we get that bumpstick naca mod at?

American Power

Ram air is not Jibberish. It is functional and it's proven. The air that "seeps" through the little space around the "cosmetic NACA duct" and that's what it is "Cosmetic" is a Joke.

GM should have designed the intake to mount up to that duct.

Halltech

Our Tech 2 says otherwise. 70 degree day: 120F IAT reading within 1 minute at idle. Moving at only 25 mph, in 1 block IAT drops 45 degrees to 75, and is in parity with the OAT within 1/2 mile.

I agree that GM might have thought this out better, but they did not want underhood lift to exceed a specified amount at speed.

Mother nature knows best. Bottom breathers, are also self cleaning during the rain.

Halltech

Ram Air works. It is real and provides a small amount of boost at high speeds, usually over 100 mph, but only when there is no filter in the pressure zone. Most high performance motorcycles have a version of ram air onboard, but the filters negate most of the gains that they would otherwise see from the pressures that develop. Anyone who does not believe ram air works, should visit a Pro Stock in the pits and ask the crew chief. It has been used for many years and is a proven science.

http://www.sportrider.com/tech/146_9912_ram/

BTW. The NACA duct is strictly an ambient air induction system, and it does work as billed.

JIm

Halltech

He posted above.

LTC Z06

I didn't say I didn't believe that it doesn't work, but like you said there are "ifs" and those "ifs" have to be engineered around. When you look at the complexity of the Porsche system for 10 HP at 186 mph you have to ask why? Prostock and F1 and SR-71s are very far from our street cars.

American Power

Jim, I agree with you about the filter. But, Having a reserve of cold air pressing against the filter is making it easier for the engine to suck down the air it needs when the throttle is opened up.

Therefore the engine is not sucking through the filter without assistance. Forced air on the outside of the filter is creating some pressure on the filters surface.

It makes sense and I feel it on my car. Especially at 100+ MPH.

Halltech

I agree with that. That is how the bikes make the additional power.

I used to make and design ram air systems for drag bikes, so I have some background. We were doing this on the Suzuki's before it became standard OP.

Jim