VGLNTE1

I've heard for pressure and speed to leave and lose it. Which is true?

rustyguns

not to mention engine smells

i have never seen any wind tunnel data on this one?!?

Bill Dearborn

The area at the back of the hood is a high pressure area. A lot of race cars pick up their cool engine air in that location. Look at the old Corvette L88 Hoods. The hood scoops faced to the rear and there was an air box that sealed the carbs from the rest of the engine compartment. HVAC cold air intakes are located here as well. NASCAR has their air intakes plumbed from the base of the windshield. How it gets to be a high pressure area is air is deflected upward over the hood and comes back down at the base of the windshield. That puts the middle of the hood in a low pressure area. The C7 and C7R have their engine cooling outlets ducted to the front of the hood so the air goes into the low pressure area.

Losing the seal won't do anything but putting some louvers toward the front of the hood would probably help with engine cooling and reducing lift.

Bill

VGLNTE1

Well I meant for pressure in the engine bay, not necessarily cooling. Doing a mile event and the recent hood breaking in half thread got me thinking. Mine has been removed for a while

Mark2009

The former.

It says to leave it. Base of windshield is high pressure area at speed.

hungryhippo

My hood looked flimsy without it at highway speeds so i put it back

Crepitus

Seal it. you dont want that pressure getting under the hood. It will reduce down force, air flow through coolers and the amount of tape you can use.

VetteDrmr

Usually the best area to modify a hood to eliminate engine bay pressure is about a foot aft of the radiator. Technically the best spot is right about on top of the radiator, but that's not really practical.

HTH, and have a good one,
Mike

VGLNTE1

That's the thing...with it, you would have more built up pressure. Without it the air would go in the front, through the rad then out the back of the hood...seems like that in my mind.

Mark2009

When you go up in an airplane and look out the window, it seems like the world is flat

VGLNTE1

Actually it looks curved

VetteDrmr

Yeah, aerodynamics can be like that. Not visually intuitive, but pressure distribution numbers don't lie. Look where the road racer hood vents are located, right about where your eye thinks would be a high pressure area, but it's actually not. Has to do with the velocity of the airflow above the surface. Air at the base of the windshield is fairly stagnant, hence the higher pressures.

Have a good one,
Mike

VGLNTE1

Hum...thanks guys!

Crepitus

High pressure on the outside is at the leading edge of the windshield and maby the leading edge of the hood, was well as the grill. low pressure is around the center of the hood, wheel opening and fender area behind the wheel opening. High pressure inside the engine bay is more evenly distributed. To improve downforce and aero; vent inside pressure to outside low pressure. ie seal the high pressure area at the base of the windshield from the inside of the engine bay.

1ED1

Take some yarn and tape it to the back of the hood see which way It goes.

Olitho

Here is a thread I started on this topic:
http://www.trackhq.com/forums/f303/c...corvette-6880/

Olitho

Here is a video of my hood flying off at 150 MPH. Look at the photo sequence at the end. It does a good job of showing the low pressure area on the hood that corresponds with the CFDs I posted on that thread. It is important to consider though that their are likely various high pressure areas under the hood, too.