? after market hood with vents to reduce engine heat?
03-14-2004, 08:58 AM
#61
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If the subject is still the VS hood and how its vent works, it all has to do with aerodynamics. We all talk about air PRESURE but what actually moves air is the lack of pressure or LOW PRESURE. Air always wants to move from an area of high pressure to one of low pressure. This hood works because the lip in front of the vent forces the air moving over it up thus creating a vacuum over the vent itself. This vacuum is what sucks the air in the engine compartment out.
A better comparison than a parachute would be a airplane wing. The air moving over the curved top surface of the wing has a longer way to travel and creates an area of low pressure. Air moving under the flat surface is unobstructed and maintains its original pressure. The air under the wing tries to move up into the low pressure area over the wing lifting the airplane with it. Its actually the act of reducing air pressure that makes a wing (and this hood) work.
A better comparison than a parachute would be a airplane wing. The air moving over the curved top surface of the wing has a longer way to travel and creates an area of low pressure. Air moving under the flat surface is unobstructed and maintains its original pressure. The air under the wing tries to move up into the low pressure area over the wing lifting the airplane with it. Its actually the act of reducing air pressure that makes a wing (and this hood) work.
03-14-2004, 09:49 AM
#64
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Loco your pics do not work unless you are a yahoo member.
BTW what are we even srguing about a this point? The point of any of these hoods quite frankly is looks. They were not modeled aerodynamically or with any concern to heat extraction - they are simple knock offs of popular designs that have now been adopted for a Z.. I think it does go without saying though that any of these hoods, if left with their respective covers open, will allow more heat to escape from the engine bay than the stock solid hood. How much of a difference? No idea - would need to formally test it with temperature probes, etc.
I see absolutely no reason why you could not use or drive these cars in teh rain or snow with the vents on the hood - with the vents off, its not a terrific idea. Personally the reason I am keeping my vents ON, except for car shows and track days) is the mere fact that with the vents off, the engine bay is bound to get utterly filthty, at least with the TS style hood I have, and thats not a by product I personally want.
BTW what are we even srguing about a this point? The point of any of these hoods quite frankly is looks. They were not modeled aerodynamically or with any concern to heat extraction - they are simple knock offs of popular designs that have now been adopted for a Z.. I think it does go without saying though that any of these hoods, if left with their respective covers open, will allow more heat to escape from the engine bay than the stock solid hood. How much of a difference? No idea - would need to formally test it with temperature probes, etc.
I see absolutely no reason why you could not use or drive these cars in teh rain or snow with the vents on the hood - with the vents off, its not a terrific idea. Personally the reason I am keeping my vents ON, except for car shows and track days) is the mere fact that with the vents off, the engine bay is bound to get utterly filthty, at least with the TS style hood I have, and thats not a by product I personally want.
03-14-2004, 11:26 AM
#65
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Originally posted by BigBadBlackTrack
Well imagine a parachute going through the air. The friction against the air makes the parachute go down slow. Also the air inside the Canopy is pretty much compressed and stagnant while it goes down. The only part that has major air movement is the on the edges. That is your stock hood setup.
Now poke some holes in that parachute then the stagnant air has somewhere to go to and it actually acts like a funnel for air. The parachute goes down faster because there is now less air friction. There is less air presure on the other side thats why it creates a vacuum. Air moves freely now. That is your vented hood setup.
Same concept why intercoolers are mounted on the front. And if they are mounted on the top theres is some sort of ram air meathod where they force air into it. Example STI.
Maybe I did have physics.
Still not enough? Grab a plastic bag and run around your house so it forms a parachute. Now light a cigarette and see if you can blow any smoke in the bag while your running. Repeat the said steps but now poke holes on the plastic bag. See what happens.
Well imagine a parachute going through the air. The friction against the air makes the parachute go down slow. Also the air inside the Canopy is pretty much compressed and stagnant while it goes down. The only part that has major air movement is the on the edges. That is your stock hood setup.
Now poke some holes in that parachute then the stagnant air has somewhere to go to and it actually acts like a funnel for air. The parachute goes down faster because there is now less air friction. There is less air presure on the other side thats why it creates a vacuum. Air moves freely now. That is your vented hood setup.
Same concept why intercoolers are mounted on the front. And if they are mounted on the top theres is some sort of ram air meathod where they force air into it. Example STI.
Maybe I did have physics.
Still not enough? Grab a plastic bag and run around your house so it forms a parachute. Now light a cigarette and see if you can blow any smoke in the bag while your running. Repeat the said steps but now poke holes on the plastic bag. See what happens.
03-15-2004, 02:02 AM
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This point is certain, that without a way for air to escape the engine compartment it would be like trying to blow air into a coke bottle. The Engineers at Nissan have taken this all into account when testing the design (if not we would be all be driving cars that overheated every 10 miles).
Now the only question is, "Does the hood's heat extraction add any value to performance?" Heat and friction are engine killers. If these hoods reduce engine compartment temps, I can't see how that would be bad.
Now the only question is, "Does the hood's heat extraction add any value to performance?" Heat and friction are engine killers. If these hoods reduce engine compartment temps, I can't see how that would be bad.
03-15-2004, 02:09 AM
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Originally posted by Loco350Z
I just installed the VS style hood on my car. Here is a link to view it. If someone knows how to post theses pics without the link please fill me in.
http://f2.pg.briefcase.yahoo.com/bc/...uments&.view=l
I just installed the VS style hood on my car. Here is a link to view it. If someone knows how to post theses pics without the link please fill me in.
http://f2.pg.briefcase.yahoo.com/bc/...uments&.view=l
Irfan View
03-16-2004, 06:21 AM
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im not a big fan of all the hood scoops etc.
i like the OEM hood design the way it is. anyone know where i can get an OEM style CF hood? it has to be real CF that is lighter then the stock hood. i dont want fiberglass and i definitely dont want it to weight as much as the OEM hood or more.
thanks
i like the OEM hood design the way it is. anyone know where i can get an OEM style CF hood? it has to be real CF that is lighter then the stock hood. i dont want fiberglass and i definitely dont want it to weight as much as the OEM hood or more.
thanks
03-17-2004, 12:07 AM
#69
here is a link to the pic of my hood. i will try to make the pic smaller when i have some more time.
http://www.everything350z.com/ubbthr...c=1&PHPSESSID=
http://www.everything350z.com/ubbthr...c=1&PHPSESSID=
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