Hood vent and downforce

[kburlar]

Hi everyone:


I like to track my 2010 SS a few times a year. When I get up in the 120 mph range, the car starts to feel a little light. I have a couple of questions.


Would a hood vent create down force to keep it more planted?


If yes, and a hood vent was installed, would it make the back end too light because the front was more firmly planted due to the newly added down force?


Thank you.

[RupertPupkin]

Depends on the design of the hood. If it’s designed like the C7 vetted where the air goes I your front grill and exits the hood scoop/vent, then it’ll create down force. You can put canards and a front splitter

[Avenging Orange]

I think even the stock camaro hood vent would help by relieving some of the pressure and allowing better air flow. I'd love to have one on my 2010.

[Aqua Blue RS/SS]

Originally Posted by RupertPupkin

Depends on the design of the hood. If it’s designed like the C7 vetted where the air goes I your front grill and exits the hood scoop/vent, then it’ll create down force. You can put canards and a front splitter

I don’t believe the vent creates extra downforce per se, as you mention it allows the air coming thru the grill, that gets trapped under the hood/car an easy escape route. Removing the rear hood seal helps a good bit there as well. The front splitter if done right will Definitely increase downforce as you mentioned. If you’ve got a ton of air getting trapped under the hood at higher speeds, that air translates into lift unless you can vent it out, which then allows the air moving over the front of the car to help plant the front rather than being over come by lift under the hood.

[Ashen 6.2]

Some good info here on the Z28 - reference #3 for hood vent info as that vent is the same for SS & Z28's.

3. Hood extractor vent
A functional carbon fiber hood extractor provides increased engine cooling by allowing hot air an exit route, but also plays an important in the car's aero performance. It provides a path for air channeled through the grille to exit out the hood and over the car. Without the vent, the air would be pushed out the bottom of the engine compartment, which could generate lift. The design is similar to the extractor featured on the Camaro ZL1.

https://www.camaro5.com/forums/showthread.php?t=330089

[1JEWLDSSRS]

Originally Posted by Aqua Blue RS/SS

I don’t believe the vent creates extra downforce per se, as you mention it allows the air coming thru the grill, that gets trapped under the hood/car an easy escape route. Removing the rear hood seal helps a good bit there as well. The front splitter if done right will Definitely increase downforce as you mentioned. If you’ve got a ton of air getting trapped under the hood at higher speeds, that air translates into lift unless you can vent it out, which then allows the air moving over the front of the car to help plant the front rather than being over come by lift under the hood.

^^^^ this exactly!! The air caught under the hood causes lift and in turn "lightens up" the front end, I installed Hex Vents in my stock hood and that all went away, as stated, the trapped air can escape. So any vent you install will allow that trapped air to escape and allow the front to remain firmer, and as stated here, a good front splitter will also help create some down force. Well said Aqua !!!

[1JEWLDSSRS]

Originally Posted by Ashen 6.2

Some good info here on the Z28 - reference #3 for hood vent info as that vent is the same for SS & Z28's.

3. Hood extractor vent
A functional carbon fiber hood extractor provides increased engine cooling by allowing hot air an exit route, but also plays an important in the car's aero performance. It provides a path for air channeled through the grille to exit out the hood and over the car. Without the vent, the air would be pushed out the bottom of the engine compartment, which could generate lift. The design is similar to the extractor featured on the Camaro ZL1.

https://www.camaro5.com/forums/showthread.php?t=330089

Awesome info sir!!

[1911 1LE]

At 120mph your car should still be very stable, but if you remove the rear hood seal it will help a lot. I'm running no seal, stock 1LE hood and a ZL1 belly pan at 196mph and it's solid as a rock. BTW, removing the seal=$0.00 spent

[kburlar]

Thanks for the info guys. Much appreciated.

[TheFlyingBananaSS]

Great info.

[SSE 4 2SS]

Originally Posted by Aqua Blue RS/SS

I don’t believe the vent creates extra downforce per se, as you mention it allows the air coming thru the grill, that gets trapped under the hood/car an easy escape route. Removing the rear hood seal helps a good bit there as well. The front splitter if done right will Definitely increase downforce as you mentioned. If you’ve got a ton of air getting trapped under the hood at higher speeds, that air translates into lift unless you can vent it out, which then allows the air moving over the front of the car to help plant the front rather than being over come by lift under the hood.

Exactly...

Originally Posted by Ashen 6.2

Some good info here on the Z28 - reference #3 for hood vent info as that vent is the same for SS & Z28's.

3. Hood extractor vent
A functional carbon fiber hood extractor provides increased engine cooling by allowing hot air an exit route, but also plays an important in the car's aero performance. It provides a path for air channeled through the grille to exit out the hood and over the car. Without the vent, the air would be pushed out the bottom of the engine compartment, which could generate lift. The design is similar to the extractor featured on the Camaro ZL1.

https://www.camaro5.com/forums/showthread.php?t=330089

Hadn’t seen this before, but yes, good info... I learned the hard way... Trial and error...

Originally Posted by 1JEWLDSSRS

^^^^ this exactly!! The air caught under the hood causes lift and in turn "lightens up" the front end, I installed Hex Vents in my stock hood and that all went away, as stated, the trapped air can escape. So any vent you install will allow that trapped air to escape and allow the front to remain firmer, and as stated here, a good front splitter will also help create some down force. Well said Aqua !!!

Yup... Additionally, by removing the weather strip at the top of the firewall, you go a long way towards reducing the high pressure area at the base of the windshield.. The air coming from under the hood increases slip stream up the glass... By reducing the high pressure area at the back of the hood, you can actually induce a Venturi effect helping scavenge more air from under the hood... and heat... Nasty stuff really...

Originally Posted by 1911 1LE

At 120mph your car should still be very stable, but if you remove the rear hood seal it will help a lot. I'm running no seal, stock 1LE hood and a ZL1 belly pan at 196mph and it's solid as a rock. BTW, removing the seal=$0.00 spent

Yup... and it gives heat an avenue of escape...

$0.00 spent, and not only does it reduce under hood air pressure induced lift, it also reduces the high volume air flow under the car, thereby reducing some speed induced lift at the rear of the car... and heat, did anyone mention under hood heat...

If you are familiar with the rule of 1/3’s with regards to photography, I recommend using it when selecting and laying out hood vents...

Coming off the front of the hood, at speed, you develop a separation boundary, an area where the slip stream breaks away from the hood... This is variable based on speed... By avoiding the front third of the hood, you avoid the high pressure slip stream areas, which would introduce more air under the hood... Too far back and you weaken the hood structure.

One example is the standard mounting location for the Hex brand Vents... I am not condoning any vent over any other... They are just vents I’m familiar with and have first hand knowledge of...

Two examples are included of the same vent, mounted in two different locations, the first, too far forward For Your Purpose, and the second, more correct for Your purpose... I cheated mine back just a bit more after considering the hood structure...

[spyderbuddy]

Even though i will not be doing anything over the posted speed limits
I can tell a difference in wet weather
the front feels more planted with the ZL1 Hood Scoop
and the wicker bill made a real difference on the rear

[rocknroll_jeph]

This is an interesting topic! I don't have any scientific evidence to back it up, but before I had a vented hood, after I washed my car and went for a drive, water would be pushed out from the front of the hood and sprayed back. This let me think there was a high pressure zone under the hood and trapped air was venting towards the front of the car.

After I changed the hood this issue never happened again. I also have seen improved lap times on the same suspension, wheels and tires. Differences are more practice, the hood and brakes so I can't rule one out over the others.

I like the idea of removing the rear cowl or hood seal as well. I can't wait to try that trick!

[SSE 4 2SS]

Originally Posted by rocknroll_jeph

This is an interesting topic! I don't have any scientific evidence to back it up, but before I had a vented hood, after I washed my car and went for a drive, water would be pushed out from the front of the hood and sprayed back. This let me think there was a high pressure zone under the hood and trapped air was venting towards the front of the car.

After I changed the hood this issue never happened again. I also have seen improved lap times on the same suspension, wheels and tires. Differences are more practice, the hood and brakes so I can't rule one out over the others.

I like the idea of removing the rear cowl or hood seal as well. I can't wait to try that trick!

Approaching and exceeding 200 mph, my factory hood was bouncing like crazy at the hinged end, near the windshield... It was catching air and building pressure, and the only escape Avenue was down, under the car... The bouncing was the hood burping excess pressure out when it couldn’t all escape down through the engine bay...

We discussed this and the decision was made on a recommendation from a fellow racer to remove the weather strip...

The hood settled down, the front end felt more planted and we saw a small decrease in coolant temps, (higher air flow through the radiator...)

For the next event, after a ton of research, I purchased and installed the vents... Notable further improvement in both speed, car settling, and coolant temps, as well as a drop in oil temps...

We continued learning at every event, occasionally on accident, sometimes via an aha moment, and once in a while through painfully expensive situations... I lifted a head, and lost the motor but learned the effectiveness of our ground effects efforts...