Hood vents question?
 

I'm thinking to cut holes in my hood and instal these hood vents https://cgi.ebay.com/ebaymotors/JDM-U...spagenameZWDVW. Where is the best spot on hood for these kind of vents? Is it worth to do this modification?
https://i17.ebayimg.com/02/i/05/82/96/59_1.JPG

By doing this, what do you hope to achieve?

I want to vent hot air under my hood since my temp went up after 80% grill block and full belly pan.

Is venting an engine undertray will do the same effect what venting the hood?

I would assume that it would be more cost effective to just take out part of your grill block. don't get me wrong, they look cool and if you want them for that then have at it. IMO, you would get the same results by taking out part of your grill block which would just take time and you may have some negative aero affects by those vents.

Ok, then I guess that they might help.

Since heat rises, I'd say that venting the undertray would only work while you're moving.

Is it causing a problem? Heat can be good.

the best place is there where the difference in pressure between the inside and outside is greatest, you can measure this with a pressure gauge, but generally this is halfway the hood at the sides. you want to make sure you stay ahead of the high pressure bubble in front of the windshield or you"ll have air going in the vents.

generally the air on the underside of a vehicle is moveing faster especially if you have an undertray so extraction there would be better, but there's a few drawbacks. if the underside of the car is less than optimal you'll likely have a lot of turbulence there, wich you don't want to add to that, and wich might prevent the extractors form working propperly. air that comes out at the top will move over the smooth car body.
also hot air, wich will be found in the engine bay, will rise... venting at the bottom will expell the coolest air but leave the hot air trapped at the top, hood vents will help here.

one car that comes to mind as a good examle of hood vents is the opel kadett E gsi (i owned the less sporty version without the vents)

here nicely highlighted in yellow
https://upload.wikimedia.org/wikipedi...tt_GSi_16V.jpg

No. Heat radiates evenly in all directions. Hot air, because it is less dense, will float on top of cooler air if any is around, since the cold air sinks to the bottom and displaces the hot air. However, in an enclosed engine compartment, there won't be any cold air displacing hot air, so no convection.

Got it! Thanx for the clarification.:thumbup: