Fording in a JK
07-08-2011, 01:28 AM
#91
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Pettym is correct it's that ram air effect that is giving you the power. By facing the scoop backwards it doesn't really net you anything. However, if your scoop is low like near the base, and right against, the windshield you are pretty much in a dead area for air pressure. There is so much turbulence and spinning of the air there it becomes a dead zone. Think of a pick up truck bed at speed, if there are leaves in the bed they will blow around and around but rarely ever leave. The same effect is more or less true at the base of a windshield. An intake here will still draw in cooler air since it's not under the hood, and it will give you more fording depth but that is about it. The motor wont starve for air since it will still suck it in but you are decreasing the tube size it can draw through, hence some people comments about trying to breath through a straw. The ram scoop kinda offsets the straw effect.
07-08-2011, 03:13 AM
#92
JK Junkie
Pettym is correct it's that ram air effect that is giving you the power. By facing the scoop backwards it doesn't really net you anything. However, if your scoop is low like near the base, and right against, the windshield you are pretty much in a dead area for air pressure. There is so much turbulence and spinning of the air there it becomes a dead zone. Think of a pick up truck bed at speed, if there are leaves in the bed they will blow around and around but rarely ever leave. The same effect is more or less true at the base of a windshield. An intake here will still draw in cooler air since it's not under the hood, and it will give you more fording depth but that is about it. The motor wont starve for air since it will still suck it in but you are decreasing the tube size it can draw through, hence some people comments about trying to breath through a straw. The ram scoop kinda offsets the straw effect.
07-08-2011, 07:10 AM
#93
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Well Adam that is because those are not hood scoops. A hood scoop is facing forward. those are vents and are there for 2 reasons.
1. To clear the carbs and air intakes on a few cars.
2. To vent hot air from stuffing to large of a motor in a "tiny" engine bay.
The air pushes through the radiator and then thanks to the base of the wind shield being a lower pressure the air flows out that direction drawing the hot air with it. If it was positive all the time that would not work, that's why I called it a dead zone. The air is so turbulent there that you can't call it positive or negative all the time. Yes there is some air pressure making it positive but the majority of the air is flowing over the windshield making that zone also negative. Plus the scoop on the camaro had a special duct coming from the air filter to draw in cold air. The system was touted as cold air duct not a ram air.
1. To clear the carbs and air intakes on a few cars.
2. To vent hot air from stuffing to large of a motor in a "tiny" engine bay.
The air pushes through the radiator and then thanks to the base of the wind shield being a lower pressure the air flows out that direction drawing the hot air with it. If it was positive all the time that would not work, that's why I called it a dead zone. The air is so turbulent there that you can't call it positive or negative all the time. Yes there is some air pressure making it positive but the majority of the air is flowing over the windshield making that zone also negative. Plus the scoop on the camaro had a special duct coming from the air filter to draw in cold air. The system was touted as cold air duct not a ram air.
Last edited by Cunnart; 07-08-2011 at 07:15 AM.
07-12-2011, 01:52 AM
#95
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07-12-2011, 03:09 AM
#96
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Plus the scoop on the camaro had a special duct coming from the air filter to draw in cold air. The system was touted as cold air duct not a ram air.
Here it is explained:
"Cowl-induction scoop: Many scoops face forward, in the direction of the oncoming air, but every so often you'll see a reversed scoop, facing away from the air stream. Why? On most cars the area at the base of the windshield is a high-pressure area. If a reversed scoop is mounted close enough to the windshield, that high pressure will force air into the scoop. Even cars that don't have hood scoops of any kind usually take their interior ventilation air from a duct in this region.
This 1969 Chevrolet Camaro has the optional "cowl induction" hood. The intake is under the raised lip of the scoop. Notice the small grilles just forward of the windshield wipers -- they're the intakes for the Camaro's interior ventilation system, which also takes its air from this high-pressure area."
This is common knowledge among muscle car guys, but the site I quoted at random is:
hxxp://ateupwithmotor.com/technology/77-hood-scoops.html