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Hood Spacers

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Cars in the 70s did that too. Not fond of it as it ruins the look, sort of like driving with the door ajar. I've been in cars with that in the summer and the heat goes right into the cold air plenum. Open the air vents and it's like having the heater on.


If you're running hot then (grudgingly) run it. If it's for some sort of 'cool factor' then don't because it's not.Cut some vents or louvers in the inner fenders where no one will see it.

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Spacing the back of the hood up usually hurts cooling. The passenger compartment fresh air intake and cowl induction hood openings are at the base of the windshield because it is a high pressure area and forces air into the opening, not allowing it out.


Racecar Engineering did a 3 issue article on wind tunnel testing for the club racer. Their test subject was a Mini Cooper. It had the hood propped open at the rear in an attempt to get better cooling. It was amazing to see the smoke get sucked right under the hood and into the engine bay. This was hurting cooling because it was pressurizing the engine bay, letting less air pass thru the radiator.


I have a friend that works at Vermont SportsCar. (They build all the Subaru Rally cars that guys like Travis Pastrana, Ken Bock and Dave Mirra drove at the X Games). When the new WRX STI came out they were doing some testing on hood opening placement to exhaust the turbo heat. The first opens were near the back of the hood and didn't seem to function very well. One of techs tied a bunch of short pieces of yarn to the mesh over the openings and they took the car out onto the highway. At speed the yarn tufts were actually getting sucked thru the mesh into the engine bay not out like they should be. They moved the openings forward on the hood and they blew up ward showing air was coming out not into the vents.


Yarn testing has always been a poor man’s way of wind tunnel testing. You can see by the direction the yarn is moving how the air is reacting.

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... If it's for some sort of 'cool factor' then don't because it's not. Cut some vents or louvers in the inner fenders where no one will see it.


Actually this is a great idea for lowering under hood heat. The front wheel openings are in a low pressure area. As air pressure builds at the front of the car it spills off to the sides. At speed air does not like bend to conform to the surface of the car at abrupt angles. The air rolling off the front of the car wants to arc outward away from the sides. This outward arc creates a low pressure area at the front wheels and draws air outward from the wheel opening.


By cutting openings from the engine bay into the wheel well you can take advanttage of the low pressure area outside the front wheels to help cool the engine.


Also by adding an airdam to the front of the car, it will help cooling at highway speeds by blocking air from under the car. This creates a low pressure area under the engine bay and pushes more air thru the radiator and off the sides. Now the air that doesn't spill off the sides is being forced thru the radiator rather than going below it. And the additional air blocked from going under the car that goes get pushed off the sides of the airdam builds even more low pressure outside the front wheels, creating even more evacuation of air from under the hood.

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