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Vent Cowl Cover?

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76
51
Exp. Type
HPDE
Exp. Level
3-5 Years
Dothan, Alabama
I tried searching for this, but I don't exactly know what it is called. On the car behind the hood where the wipers are there is the big plastic cover, if you remove it do you guys think there will be an increase in heat reduction under the hood? Also would there be any issues not having it there? Attached is a picture of the part. Just pondering some easy upgrades I can do in the garage while I wait for next season.
1598530222090.png
 

Grant 302

basic and well known psychic
Don’t remove it. It will not improve cooling...except when the car is parked.

Removing it will screw with aerodynamics and reduce the flow of engine cooling air by letting it in from the top.

If you don’t believe me, first pull the bulb seal on the hood side and tape some yarn tufts at the rear edge of the hood and watch the yarn get sucked in.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
Humm . . . Would you have interior leaks when washing or caught in a rain storm?

I just don’t know as I’ve never removed one to see what’s under there. But that’s was my first thought.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
Don’t remove it. It will not improve cooling...except when the car is parked.

Removing it will screw with aerodynamics and reduce the flow of engine cooling air by letting it in from the top.

If you don’t believe me, first pull the bulb seal on the hood side and tape some yarn tufts at the rear edge of the hood and watch the yarn get sucked in.

This is the reason to keep it in place. Come to think about it, the cowl (base of windshield) is a high pressure area.
 
1,161
2,116
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
The vent cowl cover was already removed from my car when I bought it, along with the bulb seal on hood. It doesn’t change anything from a water seal perspective - only negative from the elements is the cabin air filter is much more exposed.

While I can’t compare before to after since this is all I’ve known, I can say that running without has no adverse effects on my engine cooling. 110 degrees at AutoClub a few weeks back - car runs full sessions with coolant temps in a very safe range.

With all that said, it really comes down to aesthetics, and for anything but a full race car chasing every last oz., I would say leave it on and don’t mess with it. But if you must, let me know and I’ll buy your takeoff pieces! 😊
 

Grant 302

basic and well known psychic
I can say that running without has no adverse effects on my engine cooling.
Well, not that you know of. The air that gets sucked in at the cowl and goes underhood ends up exiting under the car. So it generates lift and adds air pressure to the engine cooling stream.

I didn’t do a velocity (dynamic pressure) measurement when I had the seal out, but my estimate at 100mph is in the 15-25 lb lift range. The cowl panels to the sheetmetal distance doesn’t open the gap much when removed so I doubt that lift estimate doubles when you remove it. The drag created would be higher than that since part of the flow is directed backwards.

I don’t think Auto Club is particularly hard on cooling, at least not for n/a coyotes. Never really felt the need for a cool down lap there, but the hottest I’ve run was only about 95°.

Again, if you or anyone doubts me, a simple yarn tuft test and video or pics would prove it either way.
 
1,161
2,116
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
I didn’t do a velocity (dynamic pressure) measurement when I had the seal out, but my estimate at 100mph is in the 15-25 lb lift range.
What year is your Boss (you need to get a vehicle profile posted 😉) Any hood vents?

With TrackSpec vents in the factory 13-14 cutouts - any impact on releiving that pressure increase or too far forward on the hood to make a difference?


Again, if you or anyone doubts me, a simple yarn tuft test and video or pics would prove it either way.

No one is doubting you - my point was if I didn’t have cooling issues at 110 ambient, then it’s not enough of an effect to worry about at any other track or lower ambient. The negative effect of lift would be a bigger concern for me.
 

Grant 302

basic and well known psychic
What year is your Boss (you need to get a vehicle profile posted 😉) Any hood vents?
The Boss is a ‘12 and the GT/Fake Boss is an ‘11 and that’s the one I’ve done most of the aero testing on. Pass on the profiles...and no on the vents for these two S197s, but yes in the ‘00 GT.

With TrackSpec vents in the factory 13-14 cutouts - any impact on releiving that pressure increase or too far forward on the hood to make a difference?

The pressure at the cowl increases with hood vents. Remove the seal and cowl panels...and you’re recirculating a small amount of the air that you vented out of the hood back under. Not in a loop, but some air would go from the radiator out the hood vent, into the cowl then down under the firewall.

No one is doubting you - my point was if I didn’t have cooling issues at 110 ambient, then it’s not enough of an effect to worry about at any other track or lower ambient. The negative effect of lift would be a bigger concern for me.
Not saying that you are doubting. That’s why I said ‘if’. The qualified statement is because somebody is or will doubt that the air at the cowl behaves this way. It’s part of the whole premise of this thread. And many, many people out there think that the cowl would vent under hood air out.

I probably should have clarified earlier that the change in cooling is minimal. And when you don’t have a cooling issue it means you have excess cooling capacity. You’re not going to notice at all when you lose a tiny bit. But take away a few percent from a car or conditions that are close to overheating and all of a sudden you’ve got a problem.

But the bigger issue is the lift component. More so pushing 150 at Auto Club. Some yarn and tape would let you see what I mean.
 
1,161
2,116
Exp. Type
Time Attack
Exp. Level
5-10 Years
SoCal
The Boss is a ‘12 and the GT/Fake Boss is an ‘11 and that’s the one I’ve done most of the aero testing on. Pass on the profiles...and no on the vents for these two S197s, but yes in the ‘00 GT.



The pressure at the cowl increases with hood vents. Remove the seal and cowl panels...and you’re recirculating a small amount of the air that you vented out of the hood back under. Not in a loop, but some air would go from the radiator out the hood vent, into the cowl then down under the firewall.


Not saying that you are doubting. That’s why I said ‘if’. The qualified statement is because somebody is or will doubt that the air at the cowl behaves this way. It’s part of the whole premise of this thread. And many, many people out there think that the cowl would vent under hood air out.

I probably should have clarified earlier that the change in cooling is minimal. And when you don’t have a cooling issue it means you have excess cooling capacity. You’re not going to notice at all when you lose a tiny bit. But take away a few percent from a car or conditions that are close to overheating and all of a sudden you’ve got a problem.

But the bigger issue is the lift component. More so pushing 150 at Auto Club. Some yarn and tape would let you see what I mean.

Get registered with Speed Ventures on Oct 3rd or 4th and I’ll bring the yarn and tape!!
 

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